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CHANGES IN R-devel

SIGNIFICANT USER-VISIBLE CHANGES

NEW FEATURES

as.integer(rl) and hence as.raw(rl) now work for a list of raw(1) elements, as proposed by Michael Chirico's PR#18696.
graphics' grid() gains optional argument nintLog.
New functions check_package_urls() and check_package_dois() in package tools for checking URLs and DOIs in package sources.
New head() and tail() methods for class "ts" time series, proposed by Spencer Graves on R-devel.
New qr.influence() function, a “bare bones” interface to the lm.influence() leave-one-out diagnostics computations; wished for in PR#18739.
Package citation() results auto-generated from the package metadata now also provide package DOIs for CRAN and Bioconductor packages.
New function grepv() identical to grep() except with the default value = TRUE.
methods(<pkg>:::<genfun>) now does report methods when neither the generic nor the methods have been exported.
pdf() gains an author argument to set the corresponding metadata field, and logical arguments timestamp and producer to optionally omit the respective metadata. (Thanks to Edzer Pebesma.)
grDevices::glyphInfo() gains rot argument to allow per-glyph rotation. (Thanks to Daniel Sabanes Bove.)
Package tools now exports functions CRAN_current_db(), CRAN_aliases_db(), CRAN_rdxrefs_db(), CRAN_archive_db(), and CRAN_authors_db().
Package tools now exports functions R() and parse_URI_reference().
Package tools now exports functions base_aliases_db() and base_rdxrefs_db().
It is now possible to set the background color for row and column names in the data editor on Windows (Rgui).
Rterm on Windows now accepts input lines of unlimited length.
file.info() on Windows now provides file owner name and domain.
Sys.info() on Windows now provides current user domain.
findInterval() gets new options checkSorted and checkNA which allow to skip relatively costly checks; related to PR#16567.
pnorm(x) underflows more gracefully.
get(nam, env) now signals a classed error, "getMissingError", as “subclass” of "missingArgError" where the latter is used also in similar situations, e.g., f <- function(x) exp(x); try(f()) .
The set operations now avoid the as.vector() transformation for same-kind apparently vector-like operands.
md5sum() can be used to compute an MD5 hash of a raw vector of bytes by using the bytes= argument instead of files=. The two arguments are mutually exclusive.
Added function sha256sum() in package tools analogous to md5sum() implementing the SHA-256 hashing algorithm.
The xtfrm() method for class "AsIs" is now considerably faster thanks to a patch provided by Ivan Krylov.
The merge() method for data frames will no longer convert row names used for indexing using I(), which will lead to faster execution in cases where sort = TRUE and all.x and/or all.y are set to TRUE.
methods package internal .requirePackage() now calls requireNamespace(p) instead of require(p), hence no longer adding packages to the search() path in cases methods or class definitions are needed. Consequently, previous workflows relying on the old behaviour will have to be amended by adding corresponding library(p) calls.
More R level messages use a common format containing "character string" for more consistency and less translation work.
available.packages() and install.packages() get an optional switch cache_user_dir, somewhat experimentally.
The sunspot.month data have been updated to Oct 2024; because of recalibration also historical numbers are changed, and we keep the previous data as sunspot.m2014 for reproducibility.
The print() method for date-time objects (POSIX.t) gets an optional digits argument for fractional seconds, passed to improved format.POSIXlt(); consequently, print(<date.time>, digits = n) allows to print fractions of seconds.

INSTALLATION on a UNIX-ALIKE

The minimum autoconf requirement for a maintainer build has been increased to autoconf 2.72.
Building the HTML (and Info) versions of the R manuals now requires texi2any from Texinfo 6.1 or later.
Failures in building the manuals under ‘doc’ now abort the installation, removing any file which caused the failure.

DEPRECATED AND DEFUNCT

is.R() is defunct. Environment variable _R_DEPRECATED_IS_R_ no longer has any effect.
Deprecated (for more than 9 years!) functions linearizeMlist, listFromMlist, and showMlist and the "MethodsList" class for S4 method handling were removed from package methods. Deprecated functions balanceMethodsList, emptyMethodsList, inheritedSubMethodLists, insertMethod, insertMethodInEmptyList, makeMethodsList, mergeMethods, MethodsList, MethodsListSelect, and SignatureMethod were made defunct, as were the "MethodsList" branches of functions assignMethodsMetaData, finalDefaultMethod, and MethodAddCoerce.
getMethods(*, table=TRUE) is also deprecated.

INSTALLATION

Control of symbol visibility is now supported on macOS (the previous check only worked on ELF platforms).

PACKAGE INSTALLATION

C-LEVEL FACILITIES

The non-API and hidden entry points Rf_setIVector, Rf_setRVector and Rf_setSVector have been removed.
The internal code for changing the parent of an environment now signals an error if the new parent is not an environment or if the change would create a cycle in the parent chain.
SET_TYPEOF now signals an error unless the old and new types have compatible memory structure and content. Use of SET_TYPE in package C code should be avoided and may be deprecated in the near future. It is better to allocate an object of the desired type in the first place.
The set of LAPACK (double and complex) routines in headers ‘R_ext/Lapack.h’ and ‘R_ext/Applic.h’ has been extended, mostly to routines actually in use by packages.
Memory allocation messages now use the (non-SI notation) "Mb", "Gb" , ..., and "Mbytes" strings as arguments instead of as part of the (translatable format) string. This is one step for PR#18297; from Henrik Bengtsson.
Header ‘R_ext/Constants.h’ (included by ‘R.h’) now always includes header ‘float.h’ or ‘cfloat’ for constants such as DBL_MAX.
Strict R headers are now the default. This removes the legacy definitions of PI, Calloc, Realloc and Free: use M_PI, R_Calloc, R_Realloc or R_Free instead.

Pro tem STRICT_R_HEADERS is defined in header ‘R_ext/RS.h’ if not already defined. This is not used in R itself and will be removed before release.
The deprecated and seemingly never-used S-compatibility macros F77_COM and F77_COMDECL have been removed from header ‘R_ext/RS.h’.

C-LEVEL API

The ‘Writing R Extensions’ TexInfo source now contains very experimental annotations for more clearly identifying the API status of C entry points. These annotations are used to produce indices for API, experimental API, and embedded API entry points in the rendered versions. This is very preliminary and may be dropped if a better approach emerges.

Also now for Fortran-callable entry points which are part of the API.
‘Writing R Extensions’ has a new section ‘Moving into C API compliance’ to help package authors move away from using non-API endpoints. This section will continue to be updated as work on clarifying and tightening the C API continues.
New API function R_mkClosure. This checks that its arguments are valid and should be used instead of allocSExp(CLOSXP followed by SET_FORMALS, SET_BODY, and SET_CLOENV.
New API functions R_ClosureFormals, R_ClosureBody, and R_ClosureEnv for extracting closure components. The existing functions R_ClosureExpr and R_BytecodeExpr have also been added to the API.
New API function R_ParentEnv corresponding to R's parent.env().
Further non-API entry points have been added to those reported by R CMD check: COMPLEX0, ddfind, DDVAL, ENSURE_NAMEDMAX, ENVFLAGS, FRAME, HASHTAB, INTERNAL, IS_ASCII, IS_UTF8, LEVELS, NAMED, PRSEEN, RDEBUG, REAL0, Rf_findVarInFrame3, SET_BODY, SET_CLOENV, SET_FORMALS, SET_PRSEEN, SET_RDEBUG, STRING_PTR, SYMVALUE, and VECTOR_PTR. Any declarations for these in public header files will be removed in the near future, and they will be hidden where possible.
Some R CMD check ‘⁠NOTE⁠’s on the use of non-API entry points have been upgraded to ‘⁠WARNING⁠’s in preparation for removing declarations and, where possible, hiding these entry points.
Additional non-API entry points have been added to those reported by R CMD check: IS_LONG_VEC, PRCODE, PRENV, PRVALUE, R_nchar, Rf_NonNullStringMatch, R_shallow_duplicate_attr, Rf_StringBlank, SET_TYPEOF, TRUELENGTH, XLENGTH_EX, and XTRUELENGTH.

UTILITIES

R CMD INSTALL (and hence check) now by default compile C++ code with -DR_NO_REMAP. For the time being this can be reverted by setting environment variable_R_CXX_USE_NO_REMAP_ to a false value (but that will be removed in the near future).

‘Writing R Extensions’ has been revised to describe the remapped entry points, for with the Rf_ prefix remains optional when used from C code (but is recommended for new C code).
R CMD check --as-cran notes bad parts in the ‘DESCRIPTION’ file's URL fields.
R CMD check now reports more warnings on long-deprecated/obsolete Fortran features reported by gfortran -Wall. For hints on how to modernize these, see https://fortranwiki.org/fortran/show/Modernizing+Old+Fortran.
Since almost all supported R versions now use UTF-8, R CMD check no longer by default reports on marked UTF-8 or Latin-1 strings in character data. Set environment variable _R_CHECK_PACKAGE_DATASETS_SUPPRESS_NOTES_ to a false value for the previous behaviour.
tools::checkDocFiles() notes more cases of usage documentation without corresponding ⁠\alias⁠.

BUG FIXES

update_pkg_po() now copies ‘.mo’ files to the translation package even if a ‘DESCRIPTION’ file exists, thanks to Michael Chirico fixing PR#18694.
Auto-generated citation() entries no longer include (additional) URLs in the ‘⁠note⁠’ field (PR#18547).
as.data.frame.list() gets a new option new.names and now preserves NA names, thus fixing the format() method for data frames, and also bug PR#18745. Relatedly, the format() method gets an option cut.names.
stem() formats correctly also in cases where rounding up, e.g., from 9.96 to 10 needs more digits; thanks to Ella Kaye and Kelly Bodwin, fixing PR#8934 during ‘R Dev Day’ at useR!2024.

Additionally, stem(x) now works normally also when length(x) == 1.
tools' toTitleCase() now works better, fixing PR#18674, thanks to Shannon Pileggi, Sarah Zeller, Reiko Okamoto, and Hugo Gruson's ‘R Dev Day’ effort.
Printing matrices (typically with many rows and or columns) now also omits columns when desirable according to option max.print, or argument max, respectively. This is primarily the work of Lorena Abad, Ekaterina Akimova, Hanne Oberman, Abhishek Ulayil, and Lionel Henry at the ‘R Dev Day’, thus fixing PR#15027.
Sys.setLanguage() now works in an LC_ALL=C R session on some platforms, warns about some failures to change the language and gets an option related to these warning messages.
Printing ls.str() now shows "<missing>" even when R's language setting is not English.
xyTable() now handles and reports NAs fixing PR#18654. Thanks to Heather Turner and Zhian Kamvar for report and patch.
as(*, "raw") now works as documented, thanks to Mikael Jagan's PR#18795.
Informational messages of e.g., print(1:1e4, max=1000), now correctly mention max in addition to getOption("max.print").
rowSums(A, dims = dd), colMeans(..), etc, give a more helpful error message when dd is not of length one, thanks to Michael Chirico's PR#18811.
seq.Date() no longer explicitly coerces results from integer to double, analogously with seq.default(), seq.int() and seq.POSIXt(), resolving a modified PR#18782.
axisTicks(usr, ...) documentation clarification for log=TRUE, fixing bug PR#18821 thanks to Duncan Murdoch.
debug() and debugonce(fun) now also accept a string fun when it names an S4 generic, fixing PR#18822 thanks to Mikael Jagan.
debugonce(<S4-simple-body>, signature=*) now works correctly when “called twice”, fixing PR#18824 thanks to Mikael Jagan.
format(dtime, digits=* / format=*) is more consistent when the POSIXt date-time object dtime has fractional (non integer) seconds. Fixes PR#17350, thanks to new contributions by LatinR's ‘R Dev Day’ participants, Heather Turner and Dirk Eddelbuettel.

CHANGES IN R 4.4.2 patched

C-LEVEL FACILITIES

The functions R_strtod and R_atof now allow hexadecimal constants without an exponent, for compatibility with their C99 versions (PR#18805).

BUG FIXES

kappa(A, exact=TRUE) for singular A returns Inf more generally, fixing PR#18817 reported by Mikael Jagan.
Fixed URLs of the sun spots (sunspot.month etc) data sets and mention future changes due to recalibration.
The parser now accepts hexadecimal constants with a decimal point without an exponent (taken as p0) as documented in ?NumericConstants (PR#18819).

CHANGES IN R 4.4.2

C-LEVEL FACILITIES

The S-compatibility macros F77_COM and F77_COMDECL defined in header ‘R_ext/RS.h’ are deprecated and will be removed shortly. We could find no record of their use.

BUG FIXES

Mathlib function lgammacor(x) no longer warns about underflow to zero for large x.
Text widths and heights were incorrectly reported by the Quartz device if the drawing context didn't exist yet (typically when drawing off-screen to a window that is yet to appear, see PR#18591).
The Quartz device could segfault in cases where paths with spaces are used in the new glyph drawing API. Thanks to Tomek Gieorgijewski (PR#18758).
On macOS in R CRAN builds, it is again possible to read little-endian UTF-16 text with a BOM from a connection using encoding="UTF-16". Users building R from source should avoid using the system libiconv in macOS 14.1 and later.
methods' internal .requirePackage() now re-enables primitive method dispatch when needed; thanks to Ivan Krylov for demystifying CRAN package check failures on the R-devel mailing list.

CHANGES IN R 4.4.1

C-LEVEL FACILITIES

Functions R_atof and R_strtod declared in header ‘R_ext/Utils.h’ are now documented in ‘Writing R Extensions’ and so formally part of the API.
The non-API entry points Rf_setSVector, Rf_StringFalse, Rf_StringTrue and Rf_isBlankString have been added to those reported by R CMD check.
The new function Rf_allocLang is now available. This provides an alternative to the idiom of calling Rf_allocList followed by SET_TYPEOF.

UTILITIES

R CMD check now reports as warnings what gfortran calls ‘Fortran 2018 deleted features’, all of which have long been marked as ‘obsolescent’ and some of which were deleted in Fortran 2008 or earlier. Fortran compilers are no longer required to support these.

BUG FIXES

as.numeric(), scan(), type.convert() and other places which use the internal C function R_strtod now require a non-empty digit sequence in a decimal or binary exponent. This aligns with the C/POSIX standard for strtod and with ?NumericConstants.
as.data.frame(m, make.names=NA) now works correctly for a matrix m with NA's in row names.
The error message from <POSIXlt>[["hour"]] and similar now mentions *[[, "hour"]], as wished for in PR#17409 and proposed by Michael Chirico.
qbinom() and potentially qpois(), qnbinom(), no longer sometimes fail accurate inversion (of pbinom(), etc), thanks to Christopher Chang's report and patch in PR#18711.
The internal help server on Windows can again serve requests sent in quick succession, fixing a regression in R 4.4.0.
debugcall(S3Generic()) now also works when a corresponding S4-generic version is in the methods cache (PR#18143).
Package tools' toTitleCase(ch0) now returns character(0) when ch0 is of zero length; fixing PR#18724, reported by David Hugh Jones.
R CMD check is no longer broken (without a check result and no explanation in ‘00check.log’) for a package which declares an invalid VignetteBuilder in ‘DESCRIPTION’ but has no vignettes.

CHANGES IN R 4.4.0

SIGNIFICANT USER-VISIBLE CHANGES

Startup banners, R --version, sessionInfo() and R CMD check no longer report (64-bit) as part of the platform as this is almost universal – the increasingly rare 32-bit platforms will still report (32-bit).

On Windows, ditto for window titles.
is.atomic(NULL) now returns FALSE, as NULL is not an atomic vector. Strict back-compatibility would replace is.atomic(foo) by (is.null(foo) || is.atomic(foo)) but should happen only sparingly.

NEW FEATURES

The confint() methods for "glm" and "nls" objects have been copied to the stats package. Previously, they were stubs which called versions in package MASS. The MASS namespace is no longer loaded if you invoke (say) confint(glmfit). Further, the "glm" method for profile() and the plot() and pairs() methods for class "profile" have been copied from MASS to stats. (profile.nls() and plot.profile.nls() were already in stats.)
The confint() and profile methods for "glm" objects have gained a possibility to do profiling based on the Rao Score statistic in addition to the default Likelihood Ratio. This is controlled by a new test = argument.
The pairs() method for "profile" objects has been extended with a which = argument to allow plotting only a subset of the parameters.
The "glm" method for anova() computes test statistics and p-values by default, using a chi-squared test or an F test depending on whether the dispersion is fixed or free. Test statistics can be suppressed by giving argument test a false logical value.
In setRepositories() the repositories can be set using their names via name = instead of index ind =.
methods() and .S3methods() gain a all.names option for the (rare) case where functions starting with a ‘⁠.⁠’ should be included.
Serializations can now be interrupted (e.g., by Ctrl-C on a Unix-alike) if they take too long, e.g., from save.image(), thanks to suggestions by Ivan Krylov and others on R-devel.
New startup option --max-connections to set the maximum number of simultaneous connections for the session. Defaults to 128 as before: allowed values up to 4096 (but resource limits may in practice restrict to smaller values).
R on Windows (since Windows 10 2004) now uses the new Segment Heap allocator. This may improve performance of some memory-intensive applications.
When R packages are built, typically by R CMD build <pkg>, the new --user=<build_user> option overrides the (internally determined) user name, currently Sys.info()["user"] or LOGNAME. This is a (modified) fulfillment of Will Landau's suggestion in PR#17530.
tools::testInstalledBasic() gets new optional arguments outDir and testSrcdir, e.g., allowing to use it in a builddir != srcdir setup, and in standard “binary” Windows installation if a source ‘tests/’ folder is present.
range(<DT_with_Inf>, finite = TRUE) now work for objects of class "Date", "POSIXct", and "POSIXlt" with infinite entries, analogously to range.default(), as proposed by Davis Vaughan on R-devel. Other range()-methods can make use of new function .rangeNum().
New .internalGenerics object complementing .S3PrimitiveGenerics, for documentation and low-level book-keeping.
grid() now invisibly returns the x- and y- coordinates at which the grid-lines were drawn.
norm(., type) now also works for complex matrices.
kappa(., exact = TRUE, norm = *) now works for all norms and also for complex matrices. In symmetric / triangular cases, the new argument uplo = "U" | "L" allows the upper or lower triangular part to be specified.
memDecompress(type = "unknown") recognizes compression in the default ‘zlib’ format as used by memCompress(type = "gzip").
memCompress() and memDecompress() will use the libdeflate library (https://github.com/ebiggers/libdeflate) if installed. This uses the same type of compression for type = "gzip" but is 1.5-2x faster than the system libz library on some common platforms: the speed-up may depend on the library version.
diff() for objects of class "Date", "POSIXct", and "POSIXlt" accepts a units argument passed via ....
Dynamic help now does a much better job of rendering package ‘DESCRIPTION’ metadata.
Rprof() gains an event argument and support for elapsed (real) time profiling on Unix (PR#18076).
filled.contour() gains a key.border argument.
tools::update_pkg_po() gets arguments pot_make and mo_make for not re-making the corresponding files, and additionally a verbose argument.
Hexadecimal string colour specifications are now accepted in short form, so, for example, we can use "#123", which is equivalent to "#112233".

Thanks to MikeFC for the original idea and Ella Kaye, Malcolm Barrett, George Stagg, and Hanne Oberman for the patch.
Plain-text help shows ⁠\var⁠ markup by angle brackets.
The new experimental primitive function declare() is intended to eventually allow information about R code to be communicated to the interpreter, compiler, and code analysis tools. The syntax for declarations is still being developed.
Functions psmirnov(), qsmirnov() and rsmirnov() in package stats have had argument two.sided renamed to alternative, to take into account that the permutation distributions of the one-sided statistics can be different in the case of ties. Consequence of PR#18582.
sort() is now an implicit S4 generic in methods.
Formatting and printing, format(z), print(z), of complex vectors z no longer zap relatively small real or imaginary parts to zero, fixing PR#16752. This is an API change, as it was documented previously to round real and imaginary parts together on purpose, producing nicer looking output. As mentioned, e.g. in the PR, this change is compatible with many other “R-like” programming environments.

We have simplified the internal code and now basically format the real and imaginary parts independently of each other.
New experimental functions Tailcall() and Exec() to support writing stack-space-efficient recursive functions.
Where characters are attempted to be plotted by pdf(), postscript() and xfig() which are not in the selected 8-bit character set (most often Latin-1) and the R session is using a UTF-8 locale, the warning messages will show the UTF-8 character rather than its bytes and one dot will be substituted per character rather than per byte. (Platforms whose iconv() does transliteration silently plot the transliteration.)

In a UTF-8 locale some transliterations are now done with a warning (e.g., dashes and Unicode minus to hyphen, ligatures are expanded, permille (‘⁠‰⁠’) is replaced by ‘⁠o/oo⁠’), although the OS may have got there first. These are warnings as they will continue to be replaced by dots in earlier versions of R.
The matrix multiplication functions crossprod() and tcrossprod() are now also primitive and S3 generic, as %*% had become in R 4.3.0.
source() and example() have a new optional argument catch.aborts which allows continued evaluation of the R code after an error.
The non-Quartz tiff() devices allow additional types of compression if supported by the platform's ‘⁠libtiff⁠’ library.
The list of base and recommended package names is now provided by tools::standard_package_names().
cairo_pdf() and cairo_ps() default to onefile = TRUE to closer match pdf() and postscript().
New option catch.script.errors provides a documented way to catch errors and then continue in non-interactive use.
L %||% R newly in base is an expressive idiom for the phrases if(!is.null(L)) L else R or if(is.null(L)) R else L.
The return value from warnings() now always inherits from "warnings" as documented, now also in the case of no warnings where it previously returned NULL.
as.complex("1i") now returns 0 + 1i instead of NA with a warning.
z <- c(NA, 1i) now keeps the imaginary part Im(z[1]) == 0, no longer coercing to NA_complex_. Similarly, cumsum(z) correctly sums real and imaginary parts separately, i.e., without “crosstalk” in case of NAs.
On Alpine Linux iconv() now maps "latin2", "latin-2", "latin9" and "latin-9" to encoding names the OS knows about (case-insensitively).
iconv(sub = "Unicode") now always zero-pads to four (hex) digits, rather than to 4 or 8. (This seems to have become the convention once Unicode restricted the number of Unicode points to 2^{21} - 1 and so will never need more than 6 digits.)
NCOL(NULL) now returns 0 instead of 1, for consistency with cbind().
The information for the Euro glyph missing from the Adobe ‘.afm’ files for the Courier, Helvetica and Times families has been copied from their URW equivalents – this will improve vertical centring in the pdf() and postscript() devices.
The included BLAS sources have been updated to those shipped with LAPACK version 3.12.0. The changes are almost entirely cosmetic.
The included LAPACK sources have been updated to version 3.12.0 and some further double-complex routines added.
There are new font families for the 2014–5 URW 2.0 fonts (see ?pdf) which are included in recent versions of Ghostscript. These have font widths for most Greek glyphs and a few others which were missing from the original versions (whose font families remain available for reproducibility, although Ghostscript-based viewers will render using the 2.0 versions).
Improve the large-n efficiency of as.matrix(<dist>), thanks an R contributors effort, notably by Tim Taylor and Heather Turner, see PR#18660.
The default and numeric methods of all.equal() get a check.class option.
zapsmall() gets new optional arguments, function mFUN and min.d, for extra flexibility; fulfills a wish in PR#18199. Also, it is now an implicit S4 generic in package methods.
The Rd filter for aspell() gains an ignore argument.
New generic function sort_by(), primarily useful for the data.frame method which can be used to sort rows of a data frame by one or more columns.
The licence headers for the RPC code in ‘src/extra/xdr’ have been updated to use the GPL-compatible licence published by Oracle America in 2010.
New function pkg2HTML() in tools to create single-page HTML reference manuals for R packages.
The byte code evaluator now uses less C stack space for recursive calls to byte-compiled functions. It also makes more of an effort to avoid allocations for scalar return values.
New completion option backtick (disabled by default) allows non-syntactic completions to be wrapped in backquotes. This is currently only useful for Jupyter notebooks via the IRkernel package, and may cause problems for other backends.
The numeric version creators now stop on invalid non-character version specifications.

INSTALLATION

The parser has been updated to work with bison 3.8.2, which is now used for the pre-generated parsers in ‘gram.c’, file.c, and ‘gramRd.c’. A few parser error messages have changed, which may affect code that relies on exact messages.

INSTALLATION on a UNIX-ALIKE

System valgrind headers are now required to use configure option --with-valgrind-instrumentation with value 1 or 2.
configure will warn if it encounters a 32-bit build, as that is nowadays almost untested.
Environment variable R_SYSTEM_ABI is no longer used and so no longer recorded in ‘etc/Renviron’ (it was not on Windows and was only ever used when preparing package tools).
If the libdeflate library and headers are available, libdeflate rather than libz is used to (de)compress R objects in lazy-load databases. Typically tasks spend up to 5% of their time on such operations, although creating lazy-data databases is one of the exceptions.

This can be suppressed if the library is available by the configure option --without-libdeflate-compression.
configure option --enable-lto=check has not worked reliably since 2019 and has been removed.
The minimum autoconf requirement for a maintainer build has been increased to autoconf 2.71.

It is intended to increase this to 2.72 for R 4.5.0: the distributed ‘configure’ file was generated using 2.72.
The minimum version requirement for an external LAPACK has been reduced to 3.9.0.
No default C++ compiler is set if no C++17 compiler is detected: there is no longer an automatic fallback to C++14 or C++11.

Compilers from the last five years should have sufficient support: for others macros CXX and CXXSTD can be set in file ‘config.site’ to provide a fallback if needed.

The Objective-C++ compiler now by default uses the standard selected by R for C++ (currently C++17) rather than the default standard for the C++ compiler (which on macOS is still C++98).

INSTALLATION on macOS

A new configure option --with-newAccelerate makes use of Apple's ‘new’ BLAS / LAPACK interfaces in their Accelerate framework. Those interfaces are only available in macOS 13.3 or later, and building requires SDK 13.3 or later (from the Command Line Tools or Xcode 14.3 or later).

By default the option uses new Accelerate for BLAS calls: to also use it for LAPACK use option --with-newAccelerate=lapack. The later interfaces provide LAPACK 3.9.1 rather than 3.2.1: 3.9.1 is from 2021-04 and does not include the improved algorithms introduced in LAPACK 3.10.0 (including for BLAS calls).

INSTALLATION on WINDOWS

The makefiles and installer scripts for Windows have been tailored to Rtools44, an update of the Rtools43 toolchain. It is based on GCC 13 and newer versions of MinGW-W64, binutils and libraries (targeting 64-bit Intel CPUs). R-devel can no longer be built using Rtools43 without changes.
Rtools44 has experimental support for 64-bit ARM (aarch64) CPUs via the LLVM 17 toolchain using lld, clang/flang-new and libc++.

UTILITIES

R CMD check notes when S4-style exports are used without declaring a strong dependence on package methods.
tools::checkRd() (used by R CMD check) detects more problems with ⁠\Sexpr⁠-based dynamic content, including bad nesting of ⁠\Sexpr⁠s and invalid arguments.
tools::checkRd() now reports Rd titles and section names ending in a period; this is ignored by R CMD check unless environment variable _R_CHECK_RD_CHECKRD_MINLEVEL_ is set to -5 or smaller.
R CMD check now notes Rd files without an ⁠\alias⁠, as long documented in ‘Writing R Extensions’ §1.3.1. The check for a missing ⁠\description⁠ has been moved from tools::checkRd() to tools::checkRdContents().
R CMD check now visits ‘inst/NEWS.Rd’ and OS-specific ‘man’ subdirectories when checking Rd files.
tools::checkDocFiles() and tools::checkRdContents() now also check internal Rd files by default, but “specially” (ignoring missing documentation of arguments).
R CMD Rdiff gets option --useEx.
R CMD check now warns on non-portable uses of Fortran KIND such as INTEGER(KIND=4) and REAL(KIND=8).

To see the failing lines set environment variable _R_CHECK_FORTRAN_KIND_DETAILS_ to a true value.
When checking Rd files, R CMD check now notes some of the “lost braces” that tools::checkRd() finds. Typical problems are Rd macros missing the initial backslash (e.g., ‘⁠code{...}⁠’), in-text set notation (e.g., ‘⁠{1, 2}⁠’, where the braces need escaping), and ⁠\itemize⁠ lists with ⁠\describe⁠-style entries of the form ⁠\item{label}{description}⁠.
R CMD INSTALL (and hence check) will compile C++ code with -DR_NO_REMAP if environment variable _R_CXX_USE_NO_REMAP_ is set to a true value. It is planned that this will in future become the default for compiling C++.
The new built-in Rd macro ⁠\dontdiff{}⁠ can be used to mark example code whose output should be ignored when comparing check output to reference output (‘tests/Examples/pkg-Ex.Rout.save’). The ⁠\dontdiff⁠ tag, like ⁠\donttest⁠, is not shown on the rendered help page, so provides a clean alternative to ‘⁠## IGNORE_RDIFF_(BEGIN|END)⁠’ comments.
R CMD build when there is no ‘NAMESPACE’, now uses the recommended exportPattern("^[^.]"), instead of exporting everything.
R CMD check now warns about non-ASCII characters in the ‘NAMESPACE’ file (in addition to R files). Such packages are not portable and may fail to install on some platforms.

C-LEVEL FACILITIES

Headers ‘R_ext/Applic.h’ and ‘R-ext/Linpack.h’ used to include ‘R_ext/BLAS.h’ although this was undocumented and unneeded by their documented entry points. They no longer do so.
New function R_missing(), factored out from do_missing(), used to fix PR#18579.
SEXP type S4SXP has been renamed to OBJSXP to support experimenting with alternative object systems. The S4SXP value can still be used in C code but is now deprecated. Based on contributions from the R Consortium's Object-Oriented Programming Working Group.
New function pow1p(x,y) for accurate (1+x)^y.
mkCharLenCE was incorrectly documented to take a size_t length but was implemented with int (and character strings in R are limited to 2^{31} - 1 bytes).

DEPRECATED AND DEFUNCT

data() no longer handles zipped data from long-defunct (since R 2.13.0) --use-zip-data installations.
The legacy graphics devices pictex() and xfig() are now deprecated. They do not support recent graphics enhancements and their font handling is rudimentary. The intention is to retain them for historical interest as long as they remain somewhat functional.
Support for encoding = "MacRoman" has been removed from the pdf() and postscript() devices – this was a legacy encoding supporting classic macOS up to 2001 and no longer has universal libiconv support.
is.R() is deprecated as no other S dialect is known to be in use (and this could only identify historical dialects, not future ones).

Further information on calls can be obtained by setting the environment variable _R_DEPRECATED_IS_R_ to ‘⁠error⁠’ which turns the deprecation warning into an error and so by default gives a traceback. (This is done by R CMD check --as-cran.)
UseMethod() no longer forwards local variables assigned in the generic function into method call environments before evaluating the method body. This makes method calls behave more like standard function calls and makes method code easier to analyze correctly.
The twelve as.data.frame.<class>() methods which were deprecated only via _R_CHECK_AS_DATA_FRAME_EXPLICIT_METHOD_ and in R CMD check --as-cran are formally deprecated now in favour of calling as.data.frame() or as.data.frame.vector(). The deprecation “check” now works also when as.data.frame() is S4 generic thanks to Ivan Krylov.
The default method for the directional comparison operators <, >, <=, and >= now signals an error when one of the operands is a language object, i.e. a symbol or a call.
For terms.formula(), deprecate abb and neg.out arguments formally in addition to just documenting it.

BUG FIXES

The methods package is more robust to not being attached to the search path. More work needs to be done.
pairwise.t.test() misbehaved when subgroups had 0 DF for variance, even with pool.sd = TRUE. (PR#18594 by Jack Berry).
Probability distribution functions [dpq]<distrib>(x, *), but also bessel[IKJY](x, .) now consistently preserve attributes(x) when length(x) == 0, e.g., for a 2 \times 0 matrix, thanks to Karolis Koncevičius' report PR#18509.
Group “Summary” computations such as sum(1:3, 4, na.rm = 5, NA, 7, na.rm = LL) now give an error instead of either 17 or NN for LL true or false, as proposed by Ivan Krylov on the R-devel mailing list. (This also means it is now an error to specify na.rm more than once.)
as.complex(x) now returns complex(real = x, imaginary = 0) for all numerical and logical x, notably also for NA or NA_integer_.
Directories are now omitted by file.copy(, recursive = FALSE) and in file.append() (PR#17337).
gsub() and sub() are now more robust to integer overflow when reporting errors caused by too large input strings (PR#18346).
Top-level handlers are now more robust to attempts to remove a handler whilst handlers are running (PR#18508).
The handling of Alt+F4 in dialogs created on Windows using GraphApp has been fixed (PR#13870).
density() more consistently computes grid values for the FFT-based convolution, following Robert Schlicht's analysis and proposal in PR#18337, correcting density values typically by a factor of about 0.999. Argument old.coords = TRUE provides back compatibility.
palette.colors() gains a name argument that defaults to FALSE controlling whether the vector of colours that is returned has names (where possible). PR#18529.
tools::xgettext() no longer extracts the (non-translatable) class names from warningCondition and errorCondition calls.
S3method(<gen>, <class>, <func>) in the ‘NAMESPACE’ file now works (again) when <func> is visible from the namespace, e.g., imported, or in base.
getParseData(f) now also works for a function defined in the first of several ‘<pkg>/R/*.R’ source files, thanks to Kirill Müller's report and Duncan Murdoch's patch in PR#16756.
Rd ⁠\Sexpr⁠ macros with nested ⁠#ifdef⁠ conditionals were not processed.
A non-blocking connection with non-default encoding (such as a socket) now correctly returns from readLines() after new data has arrived also when its EOF had been reached previously. Thanks to Peter Meilstrup's report on R-devel and Ivan Krylov's report and patch proposal in PR#18555.
tools::checkRdContents() failed to detect empty argument descriptions when they spanned multiple lines, including those generated by prompt(). These cases are now noted by R CMD check.
Plain-text help no longer outputs spurious colons in the arguments list (for multi-line ⁠\item⁠ labels in the Rd source).
kappa() and rcond() work correctly in more cases; kappa(., norm = "2") now warns that it computes the 1-norm with (default) exact = FALSE; prompted by Mikael Jagan's quite comprehensive PR#18543.
Rd skeletons generated by prompt() or promptData() now use a dummy title (so R CMD build works). tools::checkRdContents() has been updated to detect such template leftovers, including from promptPackage().
When S4 method dispatch fails because no method was found, the error message now includes the signature argument names; thanks to Michael Chirico's proposal on the R-devel list.
withAutoprint({ .. }) now preserves srcrefs previously lost, thanks to Andrew Simmons' report plus fix in PR#18572.
transform.data.frame() no longer adjusts names; in particular, untransformed variables are kept as-is, including those with syntactically invalid names (PR#17890).
The keep.source option for Rd ⁠\Sexpr⁠ blocks is no longer ignored.
The formula methods for t.test() and wilcox.test() now catch when paired is passed, addressing PR#14359; use Pair(x1, x2) ~ 1 for a paired test.
The level reported in the browser prompt was often too large. It now shows the number of browser contexts on the stack.
For cbind() and rbind(), the optional deparse.level argument is now properly passed to methods, thanks to Mikael Jagan's PR#18579 and comments there.
Some error and warning messages for large (‘long vector’) matrix(v, nr, nc) and dim(m) <- d are now correct about sizes, using long long formatting, fixing PR#18612 (and more) reported by Mikael Jagan.
readChar(useBytes = TRUE) now terminates strings even when the underlying connection uses extra spaces in the input buffer. This fixes problems with extra garbage seen with gzip connections, PR#18605.
Named capture in PCRE regular expressions now works also with more than 127 named groups (PR#18588).
Datetime functions are now robust against long jumps when dealing with internal time zone changes. This avoids confusing warnings about an invalid time zone, previously triggered by turning warnings into errors or handling them via tryCatch (PR#17966, PR#17780).
Datetime functions now restore even an empty TZ environment variable after internal time zone changes (PR#17724). This makes results of datetime functions with this (typically unintentional) setting more predictable.
drop.terms(*) now drops response as by default, keep.response = FALSE, fixing PR#18564 thanks to Mikael Jagan.
dummy.coef(.) now also works for lm()-models with character categorical predictor variables rather than factor ones, fixing PR#18635 reported by Jinsong Zhao.
formals(f) <- formals(f) now also works for a function w/o arguments and atomic constant body(f).
Correct as.function(<invalid list>, .)'s error message.
removeSource() is yet more thorough in finding and removing "srcref" and the other source references from parsed R language chunks, fixing PR#18638 thanks to Andrew Simmons.
dgeom() is more accurate now, notably when its result is very small, fixing PR#18642 thanks to the proposal of Morten Welinder, also improving other instances where C level binom_raw(x, n, ..) has x == 0 or x== n.
warning() with options(warn = 1) has improved output for multi-line messages.
axis.Date() and axis.POSIXct() now respect the par("lab") setting for the number of pretty() intervals.
Comparisons for language objects (which are based on deparsing) are now more careful about using accurate deparsed results (PR#18676).
Plain-text help (Rd2txt) now correctly preserves blank lines following single-line ⁠\dontrun⁠ code.
<POSIXlt>[*] no longer sets wrong "balanced" attribute, fixing PR#18681 thanks to Mikael Jagan.
str(<classed-call>) now deparses the call as expected, fixing PR#18684, reported by Dave Slager.
In Rd examples, code following the closing brace of a ⁠\dontrun⁠, ⁠\dontshow⁠ or ⁠\donttest⁠ tag on the same line is no longer skipped when R CMD check runs the examples.
as.data.frame(matrix(*, ncol=0)) now gets valid names() and colnames(); reported by Davis Vaughan on the R-devel list.
Internal Mathlib function stirlerr(n) is now almost fully (52-bit) accurate for all n >= ~5.9 and more accurate also in the range 1 -- 5.9. This entails small (“after 12th decimal”) changes in density functions, e.g., dgamma() in some regions of their support. The fix was partly prompted by Morten Welinder's PR#18640.
Numbers like 9876543.2 are now considered non-integer by Mathlib internal R_nonint(), amending original fix of PR#15734.
Rd comment lines no longer cause broken paragraphs in the rendered PDF and plain-text help. In code blocks, pure comment lines (starting with ‘⁠%⁠’) no longer produce an empty line.
xtabs(Freq ~ .) now consistently defaults to na.action = na.pass, using na.rm = FALSE (added as an argument) when summing over Freq (PR#17770).
tools::testInstalledPackage() is no longer silent about failures from running examples or tests and its return code no longer ignores failures from checking vignettes.

CHANGES IN R 4.3.3

NEW FEATURES

iconv() now fixes up variant encoding names such as "utf8" case-insensitively.

DEPRECATED AND DEFUNCT

The legacy encoding = "MacRoman" is deprecated in pdf() and postscript(): support was incomplete in earlier versions of R.

BUG FIXES

Arguments are now properly forwarded to methods on S4 generics with ... in the middle of their formal arguments. This was broken for the case when a method introduced an argument but did not include ... in its own formals. Thanks to Hervé Pagès for the report PR#18538.
Some invalid file arguments to pictex(), postscript() and xfig() opened a file called ‘⁠NA⁠’ rather than throw an error. These included postscript(NULL) (which some people expected to work like pdf(NULL)).
Passing filename = NA to svg(), cairo_pdf(), cairo_ps() or the Cairo-based bitmap devices opened a file called ‘⁠NA⁠’: it now throws an error.
quartz(file = NA) opened a file called ‘⁠NA⁠’, including when used as a Quartz-based bitmap device. It now gives an error.
rank(<long vector>) now works, fixing PR#18617, thanks to Ilia Kats.
seq.int() did not adequately check its length.out argument.
match(<POSIXct>, .) is correct again for differing time zones, ditto for "POSIXlt", fixing PR#18618 reported by Bastian Klein.
drop.terms(*, dropx = <0-length>) now works, fixing PR#18563 as proposed by Mikael Jagan.
drop.terms(*) keeps + offset(.) terms when it should, PR#18565, and drop.terms() no longer makes up a response, PR#18566, fixing both bugs thanks to Mikael Jagan.
getS3method("t", "test") no longer finds the t.test() function, fixing PR#18627.
pdf() and postscript() support for the documented Adobe encodings "Greek" and "Cyrilllic" was missing (although the corresponding Windows' codepages could be used).
Computations of glyph metric information for pdf() and postscript() did not take into account that transliteration could replace one character by two or more (only seen on macOS 14) and typically warned that the information was not known.
rank(x) no longer overflows during integer addition, when computing rank average for largish but not-yet long vector x, fixing PR#18630, thanks to Ilia Kats.
list.files() on Windows now returns also files with names longer that 260 bytes (the Windows limit is 260 characters). Previously, some file names particularly with ‘East Asian’ characters were omitted.
cov2cor(<0 x 0>) now works, fixing PR#18423 thanks to Mikael Jagan and Elin Waring.
cov2cor(<negative diagonal>) and similar now give one warning instead of two, with better wording, fixing PR#18424 thanks to Mikael Jagan.
tools:: startDynamicHelp() now ensures port is in proper range, fixing PR#18645.
pbeta(x, a,b) is correct now for x=0 or 1 in the boundary cases where a or b or both are 0, fixing PR#18672 thanks to Michael Fay.
pmatch(x, table) for large table, also called for data frame row selection, dfrm[nm, ], is now interruptible, fixing PR#18656.
predict(<rank-deficient lm>, newdata=*) fix computing of nbasis, see Russ Lenth's comment 29 in PR#16158.
Added a work-around for a bug in macOS 14.3.1 and higher which prevents R plots in the Quartz Cocoa device from updating on screen.

CHANGES IN R 4.3.2

NEW FEATURES

The default initialization of the "repos" option from the ‘repositories’ file at startup can be skipped by setting environment variable R_REPOSITORIES to NULL such that getOption("repos") is empty if not set elsewhere.
qr.X() is now an implicit S4 generic in methods.
iconv(to = "ASCII//TRANSLIT") is emulated using substitution on platforms which do not support it (notably Alpine Linux). This should give a human-readable conversion in ASCII on all platforms (rather than NA_character_).
trans3d() gains options continuous and verbose addressing the problem of possible “wrap around” when projecting too long curves, as reported by Achim Zeileis in PR#18537.
tools::showNonASCII() has been rewritten to work better on macOS 14 (which has a changed implementation of iconv()).
tiff(type = "quartz") (the default on macOS) now warns if compression is specified: it continues to be ignored.

INSTALLATION on a UNIX-ALIKE

There is some support for building with Intel's LLVM-based compilers on ‘⁠x86_64⁠’ Linux, such as (C) icx, (C++) ipcx and (Fortran) ifx from oneAPI 2023.x.y.
There is support for using LLVM's flang-new as the Fortran compiler from LLVM 16.0.x (preferably 17.0.0 or later).

UTILITIES

R CMD check reports the use of the Fortran 90 random number generator RANDOM_NUMBER() and the subroutines to initialize it.

‘Writing R Extensions’ has example code to use R's RNGs from Fortran.

BUG FIXES

substr(x, n, L) <- cc now works (more) correctly for multibyte UTF-8 strings x when L > nchar(x), thanks to a report and patch by ‘Architect 95’.
contrib.url(character()) now returns 0-length character() as documented, which also avoids spurious warnings from available.packages() et al. in the edge case of an empty vector of repository URLs.
readChar(., 4e8) no longer fails, thanks to Kodi Arfer's report (PR#18557).
lapply(<list>, as.data.frame) no longer warns falsely for some base vector components.
Communication between parent and child processes in the multicore part of parallel could fail on platforms that do not support an arbitrarily large payload in system functions read()/write() on pipes (seen on macOS where a restriction to INT_MAX bytes is documented, without doing a partial read unlike Linux). The payload is now split into 1Gb chunks to avoid that problem. (PR#18571)
qqplot(x,y, conf.level=.) gives better confidence bounds when length(x) != length(y), thanks to Alexander Ploner's report and patch proposal (PR#18557).
norm(<0-length>, "2") now gives zero instead of an error, as all the other norm types, thanks to Mikael Jagan's PR#18542.
Build-stage Rd macros ⁠\packageAuthor⁠ and ⁠\packageMaintainer⁠ now process ‘⁠Authors@R⁠’, fixing ‘⁠NA⁠’ results when the package ‘DESCRIPTION’ omits ‘⁠Author⁠’ and ‘⁠Maintainer⁠’ fields.
Formatting and printing complex numbers could give things like ‘⁠0.1683-0i⁠’ because of rounding error: ‘⁠-0i⁠’ is now replaced by ‘⁠+0i⁠’.
postscript() refused to accept a title comment containing the letter “W” (PR#18599).
isoreg(c(1,Inf)) signals an error instead of segfaulting, fixing PR#18603.
tiff(type = "Xlib") was only outputting the last page of multi-page plots.
tools::latexToUtf8() again knows about ‘⁠\~{n}⁠’ and other letters with tilde, fixing a regression in R 4.3.0, and about ‘⁠\^{i}⁠’ as an alternative to ‘⁠\^{\i}⁠’ (similarly with other accents). Furthermore, LaTeX codes for accented I letters are now correctly converted, also fixing related mistakes in tools::encoded_text_to_latex().
tar(*, tar = "internal") no longer creates out-of-spec tar files in the very rare case of user or group names longer than 32 bytes, fixing PR#17871 with thanks to Ivan Krylov.
When using the “internal” timezone datetime code, adding a fraction of a second no longer adds one second, fixing PR#16856 from a patch by Ivan Krylov.
tools::checkRd() no longer produces spurious notes about “unnecessary braces” from multi-line Rd results of ⁠\Sexpr⁠ macros.

CHANGES IN R 4.3.1

C-LEVEL FACILITIES

The C-level API version of R's integrate(), Rdqags() in ‘Applic.h’, now returns the correct number of integrand evaluations neval, fixing PR#18515 reported and diagnosed by Stephen Wade.
The C prototypes for LAPACK calls dspgv and dtptrs in ‘R_ext/Lapack.h’ had one too many and one too few character length arguments — but this has not caused any known issues. To get the corrected prototypes, include
```
	#include <Rconfig.h> // for PR18534fixed
	#ifdef PR18534fixed
	# define usePR18534fix 1
        #endif
	#include <R_ext/Lapack.h>
      
```
in your C/C++ code (PR#18534).

INSTALLATION

Many of the checks of esoteric Internet operations and those using unreliable external sites have been moved to a new target that is not run by default and primarily intended for the core developers. To run them use
```
	cd tests; make test-Internet-dev
```

BUG FIXES

.S3methods(), typically called from methods(), again marks methods from package base as visible.

Also, the visibility of non-base methods is again determined by the method's presence in search().
tools::Rdiff() is now more robust against invalid strings, fixing installation tests on Windows without Rtools installed (PR#18530).
Fix (new) bug in hcl.colors(2, *), by Achim Zeileis (PR#18523).
head(., <illegal>) and tail(..) now produce more useful "Error in ...." error messages, fixing PR#18362.
Package code syntax on Windows is checked in UTF-8 when UTF-8 is the native encoding.
na.contiguous(x) now also returns the first run, when it is at the beginning and there is a later one of the same length; reported to R-devel, including a fix, by Georgi Boshnakov. Further, by default, it modifies only an existing attr(*,"tsp") but otherwise no longer sets one.
chol(<not pos.def>, pivot = <T|F>) now gives a correct error or warning message (depending on pivot), thanks to Mikael Jagan's (PR#18541).

CHANGES IN R 4.3.0

SIGNIFICANT USER-VISIBLE CHANGES

Calling && or || with LHS or (if evaluated) RHS of length greater than one is now always an error, with a report of the form
```
    'length = 4' in coercion to 'logical(1)'
```
Environment variable _R_CHECK_LENGTH_1_LOGIC2_ no longer has any effect.

NEW FEATURES

The included BLAS sources have been updated to those shipped with LAPACK version 3.10.1. (This caused some platform-dependent changes to package check output.) And then to the sources from LAPACK version 3.11.0 (with changes only to double complex subroutines).
The included LAPACK sources have been updated to include the four Fortran 90 routines rather than their Fortran 77 predecessors. This may give some different signs in SVDs or eigendecompositions.. (This completes the transition to LAPACK 3.10.x begun in R 4.2.0.)
The LAPACK sources have been updated to version 3.11.0. (No new subroutines have been added, so this almost entirely bug fixes: Those fixes do affect some computations with NaNs, including R's NA.)
The parser now signals classed errors, notably in case of the pipe operator |>. The error object and message now give line and column numbers, mostly as proposed and provided by Duncan Murdoch in PR#18328.
toeplitz() is now generalized for asymmetric cases, with a toeplitz2() variant.
xy.coords() and xyz.coords() and consequently, e.g., plot(x,y, log = "y") now signal a classed warning about negative values of y (where log(.) is NA). Such a warning can be specifically suppressed or caught otherwise.
Regular expression functions now check more thoroughly whether their inputs are valid strings (in their encoding, e.g. in UTF-8).
The performance of grep(), sub(), gsub() and strsplit() has been improved, particularly with perl = TRUE and fixed = TRUE. Use of useBytes = TRUE for performance reasons should no longer be needed and is discouraged: it may lead to incorrect results.
apropos() gains an argument dot_internals which is used by the completion (help(rcompgen)) engine to also see base internals such as .POSIXct().
Support in tools::Rdiff() for comparing uncompressed PDF files is further reduced – see its help page.
qqplot(x, y, ...) gains conf.level and conf.args arguments for computing and plotting a confidence band for the treatment function transforming the distribution of x into the distribution of y (Switzer, 1976, Biometrika). Contributed by Torsten Hothorn.
Performance of package_dependencies() has been improved for cases when the number of dependencies is large.
Strings newly created by gsub(), sub() and strsplit(), when any of the inputs is marked as "bytes", are also marked as "bytes". This reduces the risk of creating invalid strings and accidental substitution of bytes deemed invalid.
Support for readLines(encoding = "bytes") has been added to allow processing special text files byte-by-byte, without creating invalid strings.
iconv(from = "") now takes into account any declared encoding of the input elements and uses it in preference to the native encoding. This reduces the risk of accidental creation of invalid strings, particularly when different elements of the input have different encoding (including "bytes").
Package repositories in getOption("repos") are now initialized from the ‘repositories’ file when utils is loaded (if not already set, e.g., in ‘.Rprofile’). (From a report and patch proposal by Gabriel Becker in PR#18405.)
compactPDF() gets a verbose option.
type.convert() and hence read.table() get new option tryLogical = TRUE with back compatible default. When set to false, converts "F" or "T" columns to character.
Added new unit prefixes "R" and "Q" for abbreviating (unrealistically large) sizes beyond 10^{27} in standard = "SI", thanks to Henrik Bengtsson's PR#18435.
as.data.frame()'s default method now also works fine with atomic objects inheriting from classes such as "roman", "octmode" and "hexmode", thus fulfilling the wish of PR#18421, by Benjamin Feakins.
The as.data.frame.vector() utility now errors for wrong-length row.names. It warned for almost six years, with “Will be an error!”.
sessionInfo() now also contains La_version() and reports codepage and timezone when relevant, in both print() and toLatex() methods which also get new option tzone for displaying timezone information when locale = FALSE.
New function R_compiled_by() reports the C and Fortran compilers used to build R, if known.
predict(<lm>, newdata = *) no longer unnecessarily creates an offset of all 0s.
solve() for complex inputs now uses argument tol and by default checks for ‘computational singularity’ (as it long has done for numeric inputs).
predict(<rank-deficient lm>, newdata=*) now obeys a new argument rankdeficient, with new default "warnif", warning only if there are non-estimable cases in newdata. Other options include rankdeficient = "NA", predicting NA for non-estimable newdata cases. This addresses PR#15072 by Russ Lenth and is based on his original proposal and discussions in PR#16158 also by David Firth and Elin Waring. Still somewhat experimental.
Rgui console implementation now works better with the NVDA screen reader when the full blinking cursor is selected. The underlying improvements in cursor handling may help also other screen readers on Windows.
The drop-field control in GraphApp can now be left with the TAB key and all controls can be navigated in the reverse order using the Shift+TAB key, improving accessibility of the Rgui configuration editor.
qnorm(<very large negative>, log.p=TRUE) is now fully accurate (instead of to “only” minimally five digits).
demo(error.catching) now also shows off withWarnings() and tryCatchWEMs().
As an experimental feature the placeholder _ can now also be used in the rhs of a forward pipe |> expression as the first argument in an extraction call, such as _$coef. More generally, it can be used as the head of a chain of extractions, such as _$coef[[2]].
Spaces in the environment variable used to choose the R session's temporary directory (TMPDIR, TMP and TEMP are tried in turn) are now fatal. (On Windows the ‘short path’ version of the path is tried and used if that does not contain a space.)
all.equal.numeric() gets a new optional switch giveErr to return the numeric error as attribute. Relatedly, stopifnot(all.equal<some>(a, b, ..)) is as “smart” now, as stopifnot(all.equal(....)) has been already, thus allowing customized all.equal<Some>() wrappers.
R on Windows is now able to work with path names longer than 260 characters when these are enabled in the system (requires at least Windows 10 version 1607). Packages should be updated to work with long paths as well, instead of assuming PATH_MAX to be the maximum length. Custom front-ends and applications embedding R need to update their manifests if they wish to allow this feature. See https://blog.r-project.org/2023/03/07/path-length-limit-on-windows for more information.
‘Object not found’ and ‘Missing argument’ errors now give a more accurate error context. Patch provided by Lionel Henry in PR#18241.
The @ operator is now an S3 generic. Based on contributions by Tomasz Kalinowski in PR#18482.
New generic chooseOpsMethod() provides a mechanism for objects to resolve cases where two suitable methods are found for an Ops Group Generic. This supports experimenting with alternative object systems. Based on contributions by Tomasz Kalinowski in PR#18484.
inherits(x, what) now accepts values other than a simple character vector for argument what. A new generic, nameOfClass(), is called to resolve the class name from what. This supports experimenting with alternative object systems. Based on contributions by Tomasz Kalinowski in PR#18485.
Detection of BLAS/LAPACK in use (sessionInfo()) with FlexiBLAS now reports the current backend.
The "data.frame" method for subset() now warns about extraneous arguments, typically catching the use of ‘⁠=⁠’ instead of ‘⁠==⁠’ in the subset expression.
Calling a:b when numeric a or b is longer than one may now be made into an error by setting environment variable _R_CHECK_LENGTH_COLON_ to a true value, along the proposal in PR#18419 by Henrik Bengtsson.
density(x, weights = *) now warns if automatic bandwidth selection happens without using weights; new optional warnWbw may suppress the warning. Prompted by Christoph Dalitz' PR#18490 and its discussants.
rm(list = *) is faster and more readable thanks to Kevin Ushey's PR#18492.
The plot.lm() function no longer produces a normal Q-Q plot for GLMs. Instead it plots a half-normal Q-Q plot of the absolute value of the standardized deviance residuals.
The print() method for class "summary.glm" no longer shows summary statistics for the deviance residuals by default. Its optional argument show.residuals can be used to show them if required.
The tapply() function now accepts a data frame as its X argument, and allows INDEX to be a formula in that case. by.data.frame() similarly allows INDICES to be a formula.
The performance of df[j] <- value (including for missing j) and write.table(df) has been improved for data frames df with a large number of columns. (Thanks to Gabriel Becker's PR#18500, PR#18503 and discussants, prompted by a report from Toby Dylan Hocking on the R-devel mailing list.)
The matrix multiply operator %*% is now an S3 generic, belonging to new group generic matrixOps. From Tomasz Kalinowski's contribution in PR#18483.
New function array2DF() to convert arrays to data frames, particularly useful for the list arrays created by tapply().

DATES and TIMES

On platforms where (non-UTC) datetimes before 1902 (or before 1900 as with system functions on recent macOS) are guessed by extrapolating time zones from 1902-2037, there is a warning at the first use of extrapolation in a session. (As all time zones post 2037 are extrapolation, we do not warn on those.)
(Platforms using --with-internal-tzone, including Windows and by default macOS). How years are printed in dates or date-times can be controlled by environment variable R_PAD_YEARS_BY_ZERO. The default remains to pad to 4 digits by zeroes, but setting value ‘⁠no⁠’ gives no padding (as used by default by glibc).
strftime() tries harder to determine the offset for the "%z" format, and succeeds on the mainstream R platforms.
strftime() has a limit of 2048 bytes on the string produced – attempting to exceed this is an error. (Previously it silently truncated at 255 bytes.)
sessionInfo() records (and by default prints) the system time zone as part of the locale information. Also, the source (system/internal) of the date-time conversion and printing functions.
Objects of class "POSIXlt" created in this version of R always have 11 components: component zone is always set, and component gmtoff is set for times in UTC and usually set on the (almost all) platforms which have C-level support, otherwise is NA.
There are comprehensive validity checks on the structure of objects of class "POSIXlt" when converting (including formatting and printing). (This avoids mis-conversions of hand-crafted objects.)
There is some support for using the native date-time routines on macOS: this is only viable on recent versions (e.g. 12.6 and 13) and does get wrong some historical changes (before 1900, during WWII). Use of --with-internal-tzone remains the default.
as.POSIXct(<numeric>) and as.POSIXlt(.) (without specifying origin) now work. So does as.Date(<numeric>).
as.Date.POSIXct(., tz) now treats several tz values, notably "GMT" as equivalent to "UTC", proposed and improved by Michael Chirico and Joshua Ulrich in PR#17674.
Experimental balancePOSIXlt() utility allows using “ragged” and or out-of-range "POSIXlt" objects more correctly, e.g., in subsetting and subassignments. Such objects are now documented. Complemented by the low-level unCfillPOSIXlt() utility.

More experimentally, a "POSIXlt" object may have an attribute "balanced" indicating if it is known to be filled or fully balanced.
Functions axis.Date() and axis.POSIXct() are rewritten to gain better default tick locations and better default formats via the corresponding pretty() methods. Thanks to Swetlana Herbrandt.
The mapping of Windows' names for time zones to IANA's ‘Olson’ names has been updated. When ICU is available (it is by default), it is used to get a mapping for the current region set in Windows. This can be overridden by setting environment variable TZ to the desired Olson name — see OlsonNames() for those currently available.

GRAPHICS

The graphics engine version, R_GE_version, has been bumped to 16 and so packages that provide graphics devices should be reinstalled.
The grDevices and grid packages have new functions for rendering typeset glyphs, primarily: grDevices::glyphInfo() and grid::grid.glyph().

Rendering of typeset glyphs is only supported so far on the Cairo-based graphics devices and on the pdf() and quartz() devices.
The defined behaviour for "clear" and "source" compositing operators (via grid::grid.group()) has been changed (to align better with simple interpretation of original Porter-Duff definitions).
Support for gradients, patterns, clipping paths, masks, groups, compositing operators, and affine transformations has been added to the quartz() device.

INSTALLATION on a UNIX-ALIKE

A system installation of generic LAPACK 3.10.0 or later will be preferred to the version in the R sources.

configure option --with-lapack=no (equivalently --without-lapack) forces compilation of the internal LAPACK sources.

If --with-lapack is not specified, a system liblapack is looked for and used if it reports version 3.10.0 or later and does not contain BLAS routines.

Packages using LAPACK will need to be reinstalled if this changes to using an external library.
On ‘⁠aarch64⁠’ Linux platforms using GCC, configure now defaults to -fPIC (instead of -fpic), as desired in PR#18326.
configure now checks conversion of datetimes between POSIXlt and POSIXct around year 2020. Failure (which has been seen on platforms missing tzdata) is fatal.
If configure option --with-valgrind-instrumentation is given value 1 or 2, option --with-system-valgrind-headers is now the default and ignored (with a warning). It is highly recommended that the system headers are installed alongside valgrind: they are part of its packaging on some Linux distributions and packaged separately (e.g. in the ‘valgrind-devel’ RPM) on others. configure will give a warning if they are not found.

The system headers will be required in a future release of R to build with valgrind instrumentation.
libcurl 8.x is now accepted by configure: despite a change in major version number it changes neither API nor ABI.

INSTALLATION on WINDOWS

The makefiles and installer scripts for Windows have been tailored to Rtools43, an update of the Rtools42 toolchain. It is based on GCC 12 and newer versions of MinGW-W64, binutils and libraries. At this time R-devel can still be built using Rtools42 without changes, but when R-devel is installed via the installer, it will by default look for Rtools43.
Old make targets rsync-extsoft and 32-bit ones that are no longer needed have been removed.
Default builds (including for packages) no longer select C99. Thus the C standard used is the default for the compiler, which for the toolchain in ‘Rtools43’ is C17. (This is consistent with Unix builds.)

PACKAGE INSTALLATION

The default C++ standard has been changed to C++17 where available (which it is on all currently checked platforms): if not C++14 or C++11 is used if available otherwise C++ is not supported.
USE_FC_LEN_T is the default: this uses the correct (compiler-dependent) prototypes for Fortran BLAS/LAPACK routines called from C/C++, and requires adjustment of many such calls – see ‘Writing R Extensions’ §6.6.1.
There is initial support for C++23 as several compilers are now supporting -std=c++23 or -std=c++2b or similar. As for C++20, there no additional configure checks for C++23 features beyond a check that the compiler reports a __cplusplus value greater than that in the C++20 standard. C++ feature tests should be used.
There is support for a package to indicate the version of the C standard which should be used to compile it, and for the installing user to specify this. In most cases R defaults to the C compiler's default standard which is C17 (a ‘bug-fix’ of C11) – earlier versions of R or compilers may have defaulted to C99.

Current options are:

USE_C17
Use a standard that is at most C17. The intention is to allow legacy packages to still be installed when later C standards become the default, including packages using new keywords as identifiers or with K&R-style function declarations. This will use C17 if available, falling back to C11.

USE_C90
Use the C90 (aka C89) standard. (As that standard did not require compilers to identify that version, all we can verify is that the compiler does not claim to be using a later standard. It may accept C99 features – for example clang accepts // to make comments.)

USE_C99
Use the C99 standard. This should be rarely needed – it avoids the few new features of C11/C17 which can be useful if a package assumes them if C17 is specified and they are not implemented.

USE_C23
Use C23 (or in future, later). Compiler/library support for C23 is still being implemented, but LLVM clang from 15.0.0 and GCC from 13 have quite extensive support.

These can be specified as part of the ‘⁠SystemRequirements⁠’ field in the package's ‘DESCRIPTION’ file or via options --use-C17 and so on of R CMD INSTALL and R CMD SHLIB.

For further details see “Writing R Extensions” §1.2.5.
(Windows) A ‘src/Makefile.ucrt’ or ‘src/Makefile.win’ file is now included after ‘R_HOME/etcR_ARCH/Makeconf’ and so no longer needs to include that file itself. Installation of a package with such a file now uses a site ‘Makevars’ file in the same way as a package with a ‘src/Makevars.win’ file would.
configure is now passed crucial variables such as CC and CFLAGS in its environment, as many packages were not setting them (as documented in ‘Writing R Extensions’ §1.2).

This has most effect where configure is used to compile parts of the package – most often by cmake or libtool which obfuscate the actual compile commands used.

Also used for configure.win and configure.ucrt on Windows.

FORTRAN FLAGS

The flag -fno-optimize-sibling-calls is no longer forced for gfortran 7 and later. It should no longer be needed now using ‘hidden’ character-length arguments when calling BLAS/LAPACK routines from C/C++ is the default even for packages. (Unless perhaps packages call Fortran code from C/C++ without using R's headers and without allowing for these arguments.)

C-LEVEL FACILITIES

The deprecated S-compatibility macros DOUBLE_* in ‘R_ext/Constants.h’ (included by ‘R.h’) have been removed.
The deprecated legacy typedefs of Sint and Sfloat in header ‘R.h’ are no longer defined, and that header no longer includes header ‘limits.h’ from C nor ‘climits’ from C++.
New macro CAD5R() is provided in ‘Rinternals.h’ and used in a few places in the R sources.
ALTREP now supports VECSXP vectors. Contributed by Gabor Csardi in PR#17620.
The Rcomplex definition (in header ‘R_ext/Complex.h’) has been extended to prevent possible mis-compilation when interfacing with Fortran (PR#18430). The new definition causes compiler warnings with static initializers such as {1, 2}, which can be changed to {.r=1, .i=2}.

Using the new definition from C++ depends on compiler extensions supporting C features that have not been incorporated into the C++ standards but are available in g++ and clang++: this may result in C++ compiler warnings but these have been worked around for recent versions of common compilers (GCC, Apple/LLVM clang, Intel).

It is intended to change the inclusion of header ‘R_ext/Complex.h’ by other R headers, so C/C++ code files which make use of Rcomplex should include that header explicitly.

UTILITIES

R CMD check does more checking of package ‘.Rd’ files, warning about invalid email addresses and (some) invalid URIs and noting empty ‘⁠\item⁠’ labels in description lists.
R CMD check now also reports problems when reading package news in md (file ‘NEWS.md’) and (optionally) plain text (file ‘NEWS’) formats.
_R_CHECK_TIMINGS_ defaults to a value from the environment even for R CMD check --as-cran; this allows for exceptionally fast or slow platforms.

It now applies to checking PDF and HTML versions of the manuals, and ‘checking CRAN incoming feasibility’.
R CMD check can optionally (but included in --as-cran) check whether HTML math rendering via KaTeX works for the package ‘.Rd’ files.
Non-interactive debugger invocations can be trapped by setting the environment variable _R_CHECK_BROWSER_NONINTERACTIVE_ to a true value. This is enabled by R CMD check --as-cran to detect the use of leftover browser() statements in the package.
The use of sprintf and vsprintf from C/C++ has been deprecated in macOS 13 and is a known security risk. R CMD check now reports (on all platforms) if their use is found in compiled code: replace by snprintf or vsnprintf respectively. [NB: whether such calls get compiled into the package is platform-dependent.]
Where recorded at installation, R CMD check reports the C and Fortran compilers used to build R.

It reports the OS in use (if known, as given by osVersion) as well as that R was built for.

It notes if a C++ standard was specified which is older than the current default: many packages have used C++11 to mean ‘not C++98’ — as C++11 is the minimum supported since R 4.0.0, that specification can probably be removed.
R CMD INSTALL reports the compilers (and on macOS, the SDK) used, and this is copied to the output of R CMD check.

Where a C++ standard is specified, it is reported.
R CMD check's ‘checking compilation flags in Makevars’ has been relaxed to accept the use of flags such as -std=f2008 in ‘⁠PKG_FFLAGS⁠’.
tools::buildVignettes() has a new argument skip, which is used by R CMD check to skip (and note) vignettes with unavailable ‘⁠\VignetteDepends⁠’ (PR#18318).
New generic .AtNames() added to enable class-specific completions after @. The formerly internal function findMatches() is now exported, mainly for use in methods for .DollarNames() and .AtNames().

DEPRECATED AND DEFUNCT

default.stringsAsFactors() is defunct.
Calling as.data.frame.<class>() directly (for 12 atomic classes) is going to be formally deprecated, currently activated by setting the environment variable _R_CHECK_AS_DATA_FRAME_EXPLICIT_METHOD_ to non-empty, which also happens in R CMD check --as-cran.

BUG FIXES

Hashed environments with sizes less than 5 can now grow. (Reported to R-devel by Duncan Garmonsway.)
as.character(<Rd>, deparse = TRUE) failed to re-escape curly braces in LaTeX-like text. (Reported by Hadley Wickham in PR#18324.)
library() now passes its lib.loc argument when requiring Depends packages; reported (with fix) in PR#18331 by Mikael Jagan.
R CMD Stangle: improved message about ‘Output’ files.
head(x, n) and tail(x, n) now signal an error if n is not numeric, instead of incidentally “working” sometimes returning all of x. Reported and discussed by Colin Fay, in PR#18357.
The "lm" method for summary() now gives the correct F-statistic when the model contains an offset. Reported in PR#18008.
C() and `contrasts<-`() now preserve factor level names when given a function object (as opposed a function name which did preserve names). Reported in PR#17616.
c(a = 1, 2)[[]] no longer matches 2 but rather signals a classed error. Reported and analysed by Davis Vaughan in PR#18367, a duplicate of PR#18004, by Jan Meis et al. For consistency, NULL[[]] is also erroneous now. x[[]] <- v gives an error of the same class "MissingSubscriptError".
The relist() function of utils now supports NULL elements in the skeleton (PR#15854).
ordered(levels = *) (missing x) now works analogously to factor(, ordered=TRUE); reported (with fix) by Achim Zeileis in PR#18389.
User-defined Rd macro definitions can now span multiple lines, thanks to a patch from Duncan Murdoch. Previously, the Rd parser silently ignored everything after the first line.
Plain-text help (tools::Rd2txt()) now preserves an initial blank line for text following description list items.
tools::Rd2HTML() and tools::Rd2latex() no longer split ⁠\arguments⁠ and ⁠\value⁠ lists at Rd comments.
tools::Rd2latex() now correctly handles optional text outside ⁠\item⁠s of argument lists as well as bracketed text at the beginning of sections, e.g., ⁠\value{[NULL]}⁠.
as.character(<POSIXt>) now behaves more in line with the methods for atomic vectors such as numbers, and is no longer influenced by options(). Ditto for as.character(<Date>). The as.character() method gets arguments digits and OutDec with defaults not depending on options(). Use of as.character(*, format = .) now warns.
Similarly, the as.character.hexmode() and *.octmode() methods also behave as good citizen methods and back compatibility option keepStr = TRUE.
The as.POSIXlt(<POSIXlt>) and as.POSIXct(<POSIXct>) default methods now do obey their tz argument, also in this case.
as.POSIXlt(<Date>) now does apply a tz (time zone) argument, as does as.POSIXct(); partly suggested by Roland Fuß on the R-devel mailing list.
as.Date.POSIXlt(x) now also works when the list components are of unequal length, aka “partially filled” or “ragged”.
expand.model.frame() looked up variables in the wrong environment when applied to models fitted without data. Reported in PR#18414.
time() now (also) uses the ts.eps = getOption("ts.eps") argument and thus by default rounds values very close to the start (or end) of a year. Based on a proposal by Andreï V. Kostyrka on R-help.
Printing of a factanal() result with just one factor and sort = TRUE now works regularly, fixing PR#17863 by Timothy Bates, thanks to the ‘R Contributors’ working group.
Printing 0-length objects of class "factor", "roman", "hexmode", "octmode", "person", "bibentry", or "citation" now prints something better, one of which fixes PR#18422, reported by Benjamin Feakins.
Sys.timezone() queries timedatectl only if systemd is loaded; addressing a report by Jan Gorecki in PR#17421.
The formula method of cor.test() had scoping problems when environment(formula) was not the calling environment; reported with a patch proposal by Mao Kobayashi in PR#18439.
attach() of an environment with active bindings now preserves the active bindings. Reported by Kevin Ushey in PR#18425.
BLAS detection now works also with system-provided libraries not available as regular files. This fixes detection of the Accelerate framework on macOS since Big Sur. Reported by David Novgorodsky.
download.file() gives a helpful error message in case of an invalid download.file.method option, thanks to Colin Fay's report in PR#18455.
Sporadic crashes of Rterm when using completion have been fixed.
Rprof() is now more reliable. A livelock in thread initialization with too short sampling interval has been fixed on macOS. A deadlock in using the C runtime has been fixed on Windows. A potential deadlock has been prevented on Unix.
Cursor placement in Rgui now works even after a fixed-width font is selected.
Mandatory options (options()) are now set on startup so that saving and restoring them always works (PR#18372).
Package installation, R CMD INSTALL or install.packages(*), now parses each of the ‘<pkg>/R/*.R’ files individually instead of first concatenating and then parse()ing the large resulting file. This allows parser or syntax errors to be diagnosed with correct file names and line numbers, thanks to Simon Dedman's report and Bill Dunlap's patch in PR#17859.

This does require syntactically self contained R source files now, fixing another inadvertent bug.
predict.lm(<model with offset>) now finds the offset in the correct environment, thanks to André Gillibert's report and patch in PR#18456.
getInitial(<formula>) now finds the selfStart model in the correct environment. (Reported by Ivan Krylov in PR#18368.)
Fix for possible segfault when using recently-added graphics features, such as gradients, clipping paths, masks, and groups with pdf(file=NULL).
class(m) <- class(m) no longer changes a matrix m by adding a class attribute.
packageDate(pkg) now only warns once if there is no pkg.
When ts() creates a multivariate time series, "mts", it also inherits from "array" now, and is.mts() is documented and stricter.
Rd2txt() now preserves line breaks of ⁠\verb⁠ Rd content and from duplicated ⁠\cr⁠. The former also fixes the rendering of verbatim output from Rd ⁠\Sexpr⁠ in plain-text help.
uniroot(f, interval) should no longer wrongly converge outside the interval in some cases where abs(f(x)) == Inf for an x at the interval boundary, thanks to posts by Ben Bolker and Serguei Sokol on R-devel.
Vectorized alpha handling in palette functions such as in gray(), rainbow(), or hcl.colors() works correctly now, thanks to Achim Zeileis' report and patch in PR#18476.
Formatting and print()ing of bibentry objects has dropped the deprecated citation.bibtex.max argument, such that the bibtex argument's default for print.bibentry() depends directly on the citation.bibtex.max option, whereas in format.bibentry() the option no longer applies.
Attempting to use a character string naming a foreign function entry point in a foreign function call in a package will now signal an error if the packages has called R_forceSymbols to specify that symbols must be used.
An error in table() could permanently set options(warn=2) promoting all subsequent warnings to errors.
The sigma() function gave misleading results for binary GLMs. A new method for objects of class "glm" returns the square root of the estimate of the dispersion parameter using the same calculation as summary.glm().
bs() and ns() in the (typical) case of automatic knot construction, when some of the supposedly inner knots coincide with boundary knots, now moves them inside (with a warning), building on PR#18442 by Ben Bolker.
R CMD on Windows now skips the site profile with --no-site-file and --vanilla even when R_PROFILE is set (PR#18512, from Kevin Ushey).

CHANGES IN R 4.2.3

C-LEVEL FACILITIES

The definition of DL_FUNC in ‘R_ext/Rdynload.h’ has been changed to be fully C-compliant. This means that functions loaded via for example R_GetCCallable need to be cast to an appropriate type if they have any arguments.
.Machine has a new element sizeof.time_t to identify old systems with a 32-bit type and hence a limited range of date-times (and limited support for dates millions of years from present).

PACKAGE INSTALLATION

(Windows) The default C++ standard had accidentally been left at C++11 when it was changed to C++14 on Unix.

BUG FIXES

As "POSIXlt" objects may be “partially filled” and their list components meant to be recycled, length() now is the length of the longest component.
as.POSIXlt.Date() could underflow for dates in the far past (more than half a million years BCE).

as.Date.POSIXlt(x) would return "1970-01-01" instead of NA in R 4.2.2, e.g., for

	x <- as.POSIXlt(c("2019-01-30","2001-1-1"))
	x$mon <- c(0L, NA); as.Date(x)

R CMD check failed to apply enabled _R_CHECK_SUGGESTS_ONLY_ to examples and vignettes (regression in R 4.2.0).
R CMD check did not re-build vignettes in separate processes by default (regression in R 4.2.0).
Running examples from HTML documentation now restores previous knitr settings and options (PR#18420).
Quartz: fonts are now located using Core Graphics API instead of deprecated ATS which is no longer supported in the macOS 13 SDK (PR#18426). This also addresses an issue where the currently used font in the Quartz device context was not correctly retained.
(Windows) Math symbols in text drawing functions are again rendered correctly (PR#18440). This fixes a regression in R 4.2.1 caused by a fix in PR#18382 which uncovered an issue in GraphApp due to which the symbol charset was not used with TT Symbol font face.
(Windows) Installing a package with a ‘src/Makefile.{win,ucrt}’ file includes ‘~/.R/Makevars.win64’ in the search for user makevars, as documented in “R Installation and Administration” and done for packages with a ‘src/Makevars.{win,ucrt}’ file.
format(<POSIXlt_w/_unbalanced_sec>, "....%OS<n>") with n > 0 no longer accidentally uses the unbalanced seconds, thanks to Suharto Anggono's report (including patch) in PR#18448.
solve.default(a, b) works around issues with some versions of LAPACK when a contains NA or NaN values.
When UseMethod() cannot dispatch, it no longer segfaults producing the error message in case of a long class(), thanks to Joris Vankerschaver's report (including patch) in PR#18447.
When example(foo, ..) produces graphics on an interactive device it needs to open itself, it now leaves devAskNewPage() unchanged even when it was FALSE, thus fixing a 14 years old ‘FIXME’.
packageDescription() again catches errors from encoding conversions. This also fixes broken packageVersion() in C locale on systems where iconv does not support transliteration.

CHANGES IN R 4.2.2

NEW FEATURES

tools::Rdiff(useDiff = TRUE) checks for the presence of an external diff command and switches to useDiff = FALSE if none is found. This allows R CMD Rdiff to always work.
On Windows, environment variable R_LIBCURL_SSL_REVOKE_BEST_EFFORT can be used to switch to only ‘best-effort’ SSL certificate revocation checks with the default "libcurl" download method. This reduces security, but may be needed for downloads to work with MITM proxies (PR#18379).
(macOS) The run-time check for libraries from XQuartz for X11 and Tcl/Tk no longer uses otool from the Apple Developer Tools (PR#18400).
The LaTeX style for producing the PDF manuals, ‘Rd.sty’, now loads the standard ‘⁠amsmath⁠’, ‘⁠amsfonts⁠’ and ‘⁠amssymb⁠’ packages for greater coverage of math commands in the Rd ⁠\eqn⁠ and ⁠\deqn⁠ macros. The ⁠\mathscr⁠ LaTeX command is also provided (via the ‘⁠mathrsfs⁠’ package, if available, or the ‘⁠amsfonts⁠’ bundle otherwise), fulfilling the wish of PR#18398.
(Windows) The default format of readClipboard() and writeClipboard() has been changed to 13 (CF_UNICODETEXT).

INSTALLATION on a UNIX-ALIKE

The PDF manuals (if built) can be compacted by the new target make compact-pdf (at the top level or in directory ‘doc/manual’).
There is now configure support for LLVM clang 15 on Linux, which defaults to position-independent (PIE) executables whereas gfortran does not.
Many small changes to ease compilation (and suppress warnings) with LLVM clang 15.

BUG FIXES

Rscript -e would fail if ‘stdin’ were closed (Reported by Henrik Bengtsson.)
qt(*, log.p=TRUE) in outer tails no longer produces NaN in its final steps, thus fixing PR#18360.
tools::Rd2latex() now escapes hashes and ampersands when writing URLs, fixing LaTeX errors with such URLs in ⁠\tabular⁠.
When isGeneric(f, fdef=*) is used with mismatching names, the warning is better understandable; reported (with fix) in PR#18370 by Gabe Becker.
poly(x, n) now works again (and is now documented) when x is a "Date" or "POSIXct" object, or of another class while fulfilling mode(x) == "numeric". This also enables poly(x, *, raw=TRUE) for such variables. Reported by Michael Chirico to R-devel.
write.table(), write.csv() and write.csv2() restore their numerical precision (internal equivalent of digits = 15) after an interrupt (PR#18384).
One can now read also byte FF from a clipboard connection (PR#18385).
source("") and source(character()) now give more helpful error messages.
R CMD check --as-cran set _R_CHECK_TIMINGS_ too late to have the intended effect.
as.POSIXlt(x) now also works with very large dates x, fixing PR#18401 reported by Hannes Mühleisen.
Files can now be extracted even from very large zip archives (PR#18390, thanks to Martin Jakt).
Non-finite objects of class "POSIXlt" are now correctly coerced to classes "Date" and "POSIXct"; following up on the extension to format() them correctly.
Added methods for is.finite(), is.infinite() and is.nan() for "POSIXlt" date-time objects.

BUG FIXES on Windows

Non-ASCII characters are now properly displayed on Windows in windows created using GraphApp via e.g. winDialogString thanks to a workaround for an at least surprising Windows behavior with UTF-8 as the system encoding (PR#18382).
Find and replace operations work again in the script editor in Rgui on Windows.
Computation of window size based on requested client size in GraphApp when running in a multi-byte locale on Windows has been fixed (regression in R 4.2.0 for users of systems where R 4.1 used a single-byte locale). Rgui again respects the number of console rows and columns given in ‘Rconsole’ file.
Rterm support for Alt+xxx sequences has been fixed to produce the corresponding character (only) once. This fixes pasting text with tilde on Italian keyboard (PR#18391).

CHANGES IN R 4.2.1

NEW FEATURES

New function utils::findCRANmirror() to find out if a CRAN mirror has been selected, otherwise fallback to the main site. This behaves in the same way as tools::CRAN_package_db() and is intended for packages wishing to access CRAN for purposes other than installing packages.

The need for this was shown by a day when the main CRAN website was offline and a dozen or so packages which had its URL hardcoded failed their checks.

INSTALLATION on a UNIX-ALIKE

The libraries searched for by --with-blas (without a value) now include BLIS (after OpenBLAS but before ATLAS). And on macOS, the Accelerate framework (after ATLAS). (This is patterned after the AX_BLAS macro from the Autoconf Archive.)
The included LAPACK sources have been updated to 3.10.1.

UTILITIES

The (full path to) the command tidy to be used for HTML validation can be set by environment variable R_TIDYCMD.
Setting environment variable _R_CHECK_RD_VALIDATE_RD2HTML_ to a false value will override R CMD check --as-cran and turn off HTML validation. This provides a way to circumvent a problematic tidy.

The 2006 version that ships with macOS is always skipped.

C-LEVEL FACILITIES

The undocumented legacy declarations of Sint, Sfloat, SINT_MAX and SINT_MIN in header ‘R.h’ are deprecated.

BUG FIXES

fisher.test(d) no longer segfaults for “large” d; fixing PR#18336 by preventing/detecting an integer overflow reliably.
tar(., files=*) now produces correctly the warning about invalid UID or GID of files, fixing PR#18344, reported by Martin Morgan.
tk_choose.files() with multi = FALSE misbehaved on paths containing spaces (PR#18334) (regression introduced in R 4.0.0).
sort(x, partial = ind, *) now works correctly notably for the non-default na.last = FALSE or TRUE, fixing PR#18335 reported by James Edwards.
Environment variable _R_CHECK_XREFS_REPOSITORIES_ is only used for checking ‘.Rd’ cross-references in R CMD check (as documented) and not for other uses looking for a CRAN mirror.
The search for a CRAN mirror when checking packages now uses getOption("repos") if that specifies a CRAN mirror, even when it does not also specify all three Bioconductor repositories (as was previously required).
The HTML code generated by tools::Rd2HTML() has been improved to pass tidy 5.8.0.

BUG FIXES on Windows

Writing to a clipboard connection works again, fixing a regression in R 4.2.0 (PR#18332). Re-using a closed clipboard connection no longer issues a spurious warning about an ignored encoding argument.
C function getlocale no longer attempts to query an unsupported category from the OS, even when requested at R level, which may cause crashes when R 4.2.0 (which uses UCRT) is embedded (reported by Kevin Ushey).
Accent keys now work in GraphApp Unicode windows, which are used by Rgui whenever running in a multibyte locale (so also in UTF-8, hence fixing a regression in R 4.2.0 for users of systems where R 4.1 used a single-byte locale).
Completion in Rgui now works also with non-ASCII characters.
Rgui no longer truncates usage information with --help.
Text injection from external applications via SendInput now works in GraphApp Unicode windows, fixing a regression in R 4.2.0 for Rgui users of systems where R 4.1 used a single-byte locale but R 4.2.0 uses UTF-8.
Performance of txtProgressBar() in Rgui when running in a multi-byte locale has been improved (fixing a performance regression in R 4.2.0 for users of systems where R 4.1 used a single-byte locale).
The script editor in Rgui now works also on systems using UTF-8 as the native encoding. Users of the script editor have to convert their scripts with non-ASCII characters to UTF-8 before reading them in R 4.2.1 or newer (on recent Windows where UTF-8 is used). This fixes a regression in R 4.2.0, which prevented some operations with scripts when they contained non-ASCII characters.

CHANGES IN R 4.2.0

SIGNIFICANT USER-VISIBLE CHANGES

The formula method of aggregate() now matches the generic in naming its first argument x (resolving PR#18299 by Thomas Soeiro).

This means that calling aggregate() with a formula as a named first argument requires name formula in earlier versions of R and name x now, so portable code should not name the argument (code in many packages did).
Calling && or || with either argument of length greater than one now gives a warning (which it is intended will become an error).
Calling if() or while() with a condition of length greater than one gives an error rather than a warning. Consequently, environment variable _R_CHECK_LENGTH_1_CONDITION_ no longer has any effect.
Windows users should consult the WINDOWS section below for some profound changes including
- Support for 32-bit builds has been dropped.
- UTF-8 locales are used where available.
- The default locations for the R installation and personal library folder have been changed.
Thanks to Tomas Kalibera for months of work on the Windows port for this release.

NEW FEATURES

matrix(x, n, m) now warns in more cases where length(x) differs from n * m, as suggested by Abby Spurdle and Wolfgang Huber in Feb 2021 on the R-devel mailing list.

This warning can be turned into an error by setting environment variable _R_CHECK_MATRIX_DATA_ to ‘⁠TRUE⁠’: R CMD check --as-cran does so unless it is already set.
Function file_test() in package utils gains tests for symlinks, readability and writability.
capabilities("libxml") is now false.

The description of capabilities("http/ftp") now reflects that it refers to the default method, no longer the internal one.
simplify2array() gains an except argument for controlling the exceptions used by sapply().
Environment variables R_LIBS_USER and R_LIBS_SITE are both now set to the R system default if unset or empty, and can be set to NULL to indicate an empty list of user or site library directories.
The warning for axis()(-like) calls in cases of relatively small ranges (typically in log-scale situations) is slightly improved and suppressed from explicit calls to .axisPars() as has always been the intention.
The contrasts setter function `contrasts<-` gains an explicit default how.many = NULL rather than just using missing(how.many).
grid.pretty() gains a new optional argument n = 5.
There is a new function .pretty() with option bounds as a technical-utility version of pretty(). It and pretty() gain a new argument f.min with a better than back-compatible default.
Function grDevices::axisTicks() and related functions such as graphics::axis() work better, notably for the log scale; partly because of the pretty() improvements, but also because care is taken e.g., when ylim is finite but diff(ylim) is infinite.
nclass.FD() gains a digits option.
The R Mathlib internal C function bd0() (called indirectly from a dozen probability density and distribution functions such as dpois(), dbinom(), dgamma(), pgamma() etc) has been complemented by a more sophisticated and (mostly) more accurate C function ebd0(), currently called only by internal dpois_raw() improving accuracy for R level dpois() and potentially others calling it such as dnbinom(), dgamma() or pgamma(). (Thanks to Morten Welinder's PR#15628.)
write.ftable() gains sep = " " argument as suggested by Thomas Soeiro.
The names of the locale categories supported by R's Sys.getlocale() and Sys.setlocale() are now provided by variable .LC.categories in the base namespace.
The Date and POSIXt methods for hist() and the histogram method for plot() now also use the new default col = "lightgray" in consistency with the corresponding change to hist()'s default for R 4.0.0.
hist.default() gains new fuzz argument, and the histogram plot method no longer uses fractional axis ticks when displaying counts ("Frequency").
mapply() and hence Map() now also obey the “max-or-0-if-any” recycling rule, such that, e.g., Map(`+`, 1:3, 1[0]) is valid now.
as.character(<obj>) for "hexmode" or "octmode" objects now fulfils the important basic rule as.character(x)[j] === as.character(x[j]).
The set utility functions, notably intersect() have been tweaked to be more consistent and symmetric in their two set arguments, also preserving a common mode.
substr(ch, start,end) <- new now e.g., preserves names(ch); ditto for substring(), thanks to a patch from Brodie Gaslam.
plot(<lm>) gains a extend.ylim.f argument, in partial response to PR#15285; further PR#17784 is fixed thanks to several contributors and a patch by Elin Waring. The Cook's dist contours get customizable via cook.col and cook.lty with a different default color and their legend is nicer by default and customizable via cook.legendChanges.
Attempting to subset an object that is not subsettable now signals an error of class notSubsettableError. The non-subsettable object is contained in the object field of the error condition.
Subscript-out-of-bounds errors are now signaled as errors of class subscriptOutOfBoundsError.
Stack-overflow errors are now signaled as errors inheriting from class stackOverflowError. See ?stackOverflowError for more details.
New partly experimental Sys.setLanguage() utility, solving the main problem of PR#18055.
gettext() and gettextf() get a new option trim = TRUE which when set to false allows translations for strings such as "Execution halted\n" typical for C code.
An experimental implementation of hash tables is now available. See ?hashtab for more details.
identical() gains a extptr.as.ref argument for requesting that external pointer objects be compared as reference objects.
reorder() gets an argument decreasing which it passes to sort() for level creation; based on the wish and patch by Thomas Soeiro in PR#18243.
as.vector() gains a data.frame method which returns a simple named list, also clearing a long standing ‘FIXME’ to enable as.vector(<data.frame>, mode="list"). This breaks code relying on as.vector(<data.frame>) to return the unchanged data frame.
legend() is now vectorized for arguments cex, x.intersp, and text.width. The latter can now also be specified as a vector (one element for each column of the legend) or as NA for computing a proper column wise maximum value of strwidth(legend). The argument y.intersp can be specified as a vector with one entry for each row of the legend.

legend() also gains new arguments title.cex and title.font. Thanks to Swetlana Herbrandt.
Deparsing no longer remaps attribute names dim, dimnames, levels, names and tsp to historical S-compatible names (which structure() maps back).
sample() and sample.int() have additional sanity checks on their size and n arguments.

all.equal.numeric() gains a sanity check on its tolerance argument – calling all.equal(a, b, c) for three numeric vectors is a surprisingly common error.

mean(na.rm =), rank(na.last =), barplot(legend.text =), boxplot(), contour(drawlabels =), polygon(border =) and methods::is(class2 =) have more robust sanity checks on their arguments.

R CMD Rd2pdf (used by R CMD check) has a more robust sanity check on the format of \alias{} commands.
psigamma(x, deriv) for negative x now also works for deriv = 4 and 5; their underlying C level dpsifn() is documented in ‘Writing R Extensions’.
The HTML help system now uses HTML5 (wish of PR#18149).
ks.test() now provides exact p-values also with ties and MC p-values in the two-sample (Smirnov) case. By Torsten Hothorn.
ks.test() gains a formula interface, with y ~ 1 for the one-sample (Kolmogorov) test and y ~ group for the two-sample (Smirnov) test. Contributed by Torsten Hothorn.
The return value from ks.test() now has class c("ks.test", "htest") – packages using try() need to take care to use inherits() and not == on the class.
New functions psmirnov(), qsmirnov() and rsmirnov() in package stats implementing the asymptotic and exact distributions of the two-sample Smirnov statistic.
iconv() now allows sub = "c99" to use C99-style escapes for UTF-8 inputs which cannot be converted to encoding to.
In a forward pipe |> expression it is now possible to use a named argument with the placeholder _ in the rhs call to specify where the lhs is to be inserted. The placeholder can only appear once on the rhs.
The included LAPACK sources have been updated to version 3.10.0, except for the four Fortran 77 routines which 3.10.0 has re-implemented in Fortran 90 (where the older versions have been retained as the R build process does not support Fortran 90).
path.expand() and most other uses of tilde expansion now warn if a path would be too long if expanded. (An exception is file.exists(), which silently returns false.)
trunc(<Date>, *) now supports units = "months" or "years" for consistency with the POSIXt method, thanks to Dirk Eddelbuettel's proposal in PR#18099.
list2DF() now checks that its arguments are of the same length, rather than use recycling.
The HTML help system has several new features: LaTeX-like math can be typeset using either KaTeX or MathJax, usage and example code is highlighted using Prism, and for dynamic help the output of examples and demos can be shown within the browser if the knitr package is installed. These features can be disabled by setting the environment variable _R_HELP_ENABLE_ENHANCED_HTML_ to a false value.

GRAPHICS

The graphics engine version, R_GE_version, has been bumped to 15 and so packages that provide graphics devices should be reinstalled.
The grid package now allows the user to specify a “vector” of pattern fills. The fill argument to gpar() accepts a list of gradients and/or patterns and the functions linearGradient(), radialGradient(), and pattern() have a new group argument.

Points grobs (data symbols) can now also have a pattern fill.

The grobCoords() function now returns a more informative and complex result.
The grid package has new functions for drawing isolated groups: grid.group(), grid.define(), and grid.use(). These functions add compositing operators and affine transformations to R's graphics capabilities.

The grid package also has new functions for stroking and filling paths: grid.stroke(), grid.fill(), and grid.fillStroke().

A new function as.path() allows the user to specify the fill rule for a path that is to be used for clipping, stroking, or filling; available options are "winding" and "evenodd". A new function as.mask() allows the user to specify the type of a mask; available options are "alpha" and "luminance".

These new features are only supported so far (at most) on the Cairo-based graphics devices and on the pdf() device.
dev.capabilities() reports on device support for the new features.
par() now warns about unnamed non-character arguments to prevent misuse such as {usr <- par("usr"); par(usr)}.

WINDOWS

R uses UTF-8 as the native encoding on recent Windows systems (at least Windows 10 version 1903, Windows Server 2022 or Windows Server 1903). As a part of this change, R uses UCRT as the C runtime. UCRT should be installed manually on systems older than Windows 10 or Windows Server 2016 before installing R.
The default personal library on Windows, folder ‘R\win-library\x.y’ where ‘x.y’ stands for R release ‘x.y.z’, is now a subdirectory of Local Application Data directory (usually a hidden directory ‘C:\Users\username\AppData\Local’). Use shell.exec(.libPaths()[1]) from R to open the personal library in Explorer when it is first in the list (PR#17842).
R uses a new 64-bit Tcl/Tk bundle. The previous 32-bit/64-bit bundle had a different layout and can no longer be used.
Make files and installer scripts for Windows have been tailored to ‘Rtools42’, the newly recommended 64-bit gcc 10.3 MinGW-W64 UCRT toolchain.
‘Rtools42’ by default uses the Windows security features ASLR and DEP; hence CRAN builds of R and packages also do.
R now supports files ‘Makevars.ucrt’, ‘Makefile.ucrt’, ‘configure.ucrt’ and ‘cleanup.ucrt’ in packages, which are used in preference to the ‘.win’ variants. This allows keeping the ‘.win’ files around to support older versions of R. This feature will be removed in the future once support for older versions of R would no longer be needed.
R.version gains a new field crt (only on Windows) to denote the C runtime. The value is "ucrt".
On Windows, download.file(method = "auto") and url(method = "default") now follow Unix in using "libcurl" for all except ‘⁠file://⁠’ URIs.
‘Rtools42’ includes an unpatched Msys2 build of GNU tar. Paths including drive letters can be made to work by adding --force-local to environment variable TAR_OPTIONS. (‘Rtools40’ and earlier included a patched version which defaulted to this option.)
Installer builds of R automatically find the ‘Rtools42’ software collection as well as the compiler toolchain. No PATH setting is required from the user.
The default installation directory of R for a user-only installation has been changed to the User Program Files directory (usually a hidden directory ‘C:\Users\username\AppData\Local\Programs’) to follow Windows conventions. Use shell.exec(R.home()) from R to open the R installation directory in Explorer (PR#17842).
R now supports installation-time patching of packages. Patches may be installed from a supplied URL or a local directory or disabled. Patches are included into the installed packages for reference. This experimental feature may be removed in the future.
libcurl is now required for building from source.
The clipboard connection now works also with text in other than the current native encoding (PR#18267, with Hiroaki Yutani). Text is always pasted to the clipboard in UTF16-LE and the encoding argument is ignored.
The internal case-changing functions are now used by default on Windows – this circumvents problems (for example with E acute) of the UCRT Windows' runtime.
R on Windows now uses the system memory allocator. Doug Lea's allocator was used since R 1.2.0 to mitigate performance limitations seen with system allocators on earlier versions of Windows.
memory.limit() and memory.size() are now stubs on Windows (as on Unix-alikes).
Applications embedding R on Windows can now use additional callbacks, which have so far only been available only on Unix (PR#18286).

INSTALLATION

Facilities for accessing ‘⁠ftp://⁠’ sites are no longer tested (except pro tem for curlGetHeaders()) as modern browsers have removed support.
R can now be built with ‘⁠DEFS = -DSTRICT_R_HEADERS⁠’ .

PACKAGE INSTALLATION

R CMD INSTALL no longer tangles vignettes. This completes an R CMD build change in R 3.0.0 and affects packages built before R 3.0.2. Such packages should be re-made with R CMD build to have the tangled R code of vignettes shipped with the tarball.
USE_FC_LEN_T will become the default: this uses the correct prototypes for Fortran BLAS/LAPACK routines called from C/C++, and requires adjustment of most such calls – see ‘Writing R Extensions’ §6.6.1. (This has been supported since R 3.6.2.)
Package installation speed for packages installed with keep.source has been improved. This resolve the issue reported by Ofek Shilon in PR#18236.

UTILITIES

R CMD check can optionally report files/directories left behind in home, ‘/tmp’ (even though TMPDIR is set) and other directories. See the “R Internals” manual for details.
R CMD check now reports byte-compilation errors during installation. These are not usually fatal but may result in parts of the package not being byte-compiled.
_R_CHECK_DEPENDS_ONLY_ can be applied selectively to examples, tests and/or vignettes in R CMD check: see the “R Internals” manual.
_R_CHECK_SRC_MINUS_W_IMPLICIT_ now defaults to true: recent versions of Apple clang on macOS have made implicit function declarations in C into a compilation error.
R CMD check --as-cran makes use of the environment variable AUTORECONF. See the “R Internals” manual §8 for further details.
R CMD check --use-valgrind also uses valgrind when re-building vignettes as some non-Sweave vignettes unhelpfully comment out all their code when R CMD check runs vignettes.
Errors in re-building vignettes (unless there are LaTeX errors) are reported by R CMD check as ‘⁠ERROR⁠’ rather than ‘⁠WARNING⁠’ when running vignettes has been skipped (as it frequently is in CRAN checks and by --as-cran).
R CMD Rd2pdf gains a --quiet option that is used by R CMD build when building the PDF package manual.
R CMD Rd2pdf now always runs LaTeX in batch mode, consistent with Texinfo \ge 6.7. The --batch option is ignored.
R CMD build and R CMD check now include the Rd file name and line numbers in the error message of an ⁠\Sexpr⁠ evaluation failure.
For packages using the ⁠\doi⁠ Rd macro (now an install-time ⁠\Sexpr⁠) but no other dynamic Rd content, R CMD build now produces a smaller tarball and is considerably faster – skipping temporary package installation.
R CMD check can optionally (but included in --as-cran) validate the HTML produced from the packages ‘.Rd’ files. See https://blog.r-project.org/2022/04/08/enhancements-to-html-documentation/: this needs a fairly recent version of HTML Tidy to be available.

C-LEVEL FACILITIES

The non-API header ‘R_ext/R-ftp-http.h’ is no longer provided, as the entry points it covered are now all defunct.
A number of non-API declarations and macro definitions have been moved from the installed header ‘Rinternals.h’ to the internal header ‘Defn.h’. Packages that only use entry points and definitions documented to be part of the API as specified in ‘Writing R Extensions’ §6 should not be affected.
The macro USE_RINTERNALS no longer has any effect when compiling package code. Packages which also use R_NO_REMAP will need to ensure that the remapped names are used for calls to API functions that were formerly also made available as macros.
The deprecated legacy S-compatibility macros PROBLEM, MESSAGE, ERROR, WARN, WARNING, RECOVER, ... are no longer defined in ‘R_ext/RS.h’ (included by ‘R.h’). Replace these by calls to Rf_error and Rf_warning (defined in header ‘R_ext/Error.h’ included by ‘R.h’).

Header ‘R_ext/RS.h’ no longer includes ‘R_ext/Error.h’.
Header ‘R_ext/Constants.h’ (included by ‘R.h’) when included from C++ now includes the C++ header ‘cfloat’ rather than the C header ‘float.h’ (now possible as C++11 is required).
The legacy S-compatibility macros DOUBLE_* in ‘R_ext/Constants.h’ (included by ‘R.h’) are deprecated.
The deprecated S-compatibility macros SINGLE_* in ‘R_ext/Constants.h’ (included by ‘R.h’) have been removed.
R_Calloc, R_Free and R_Realloc are preferred to their unprefixed forms and error messages now use the prefix. These forms were introduced in R 3.4.0 and are available even when STRICT_R_HEADERS is defined.
rmultinom has been documented in ‘Writing R Extensions’ §6 so is now part of the R API.
Similarly, Rtanpi, called from R level tanpi() is now part of the R API.
The long-deprecated, undocumented and non-API entry point call_R is no longer declared in ‘R_ext/RS.h’ (included by ‘R.h’).
The header ‘S.h’ which has been unsupported since Jan 2016 has been removed. Use ‘R.h’ instead.

DEPRECATED AND DEFUNCT

The (non-default and deprecated) method = "internal" for download.file() and url() no longer supports ‘⁠http://⁠’ nor ‘⁠ftp://⁠’ URIs. (It is used only for ‘⁠file://⁠’ URIs.)

On Windows, download.file(method = "wininet") no longer supports ‘⁠ftp://⁠’ URIs. (It is no longer the default method, which is "libcurl" and does.)

On Windows, the deprecated method = "wininet" now gives a warning for ‘⁠http://⁠’ and ‘⁠https://⁠’ URIs for both download.file() and url(). (It is no longer the default method.)
On Windows, the command-line option --max-mem-size and environment variable R_MAX_MEM_SIZE are defunct. The memory allocation limit was important for 32-bit builds, but these are no longer supported.
default.stringsAsFactors() is now formally deprecated, where that was only mentioned on its regular help page, previously. So it now gives a warning if called.
unix.time() is defunct now; it had been deprecated since R 3.4.0.

BUG FIXES

Setting digits = 0 in format(), print.default() (and hence typically print()) or options() is again invalid. Its behaviour was platform-dependent, and it is unclear what “zero significant digits” should mean (PR#18098).
Messages from C code in the ‘cairo’ section of package grDevices are now also offered for translation, thanks to Michael Chirico's PR#18123.
mean(x) with finite x now is finite also without "long.double" capability.
R CMD Rd2pdf no longer leaves an empty build directory behind when it aborts due to an already existing output file. (Thanks to Sebastian Meyer's PR#18141.)
density(x, weights = w, na.rm = TRUE) when anyNA(x) is true, now removes weights “in parallel” to x, fixing PR#18151, reported by Matthias Gondan. Additionally, it gets a subdensity option.
Conversion of ⁠\Sexpr[]{<expR>}⁠ to LaTeX or HTML no longer produces long blocks of empty lines when <expR> itself contains several lines all producing empty output. Thanks to a report and patch by Ivan Krylov posted to R-devel.
R CMD build no longer fails if a package vignette uses child documents and ‘inst/doc’ exists. (Thanks to Sebastian Meyer's PR#18156.)
When an R documentation (‘help’ source) file ‘man/foo.Rd’ in a package has ⁠\donttest{..}⁠ examples with a syntax error, it is now signalled as ERROR and with correct line numbers relating to the ‘*-Ex.R’ file, thanks to Duncan Murdoch and Sebastian Meyer's reports and patch proposals in PR#17501.
Improved determination of the correct translation domain in non-base packages, addressing the combination of PR#18092 and PR#17998 (#c6) with reports and augmented patch #2904 by Suharto Anggono.

Note that "R-base" is no longer the default domain e.g., for top-level calls to gettext(); rather translation needs explicit domain = * specification in such cases.
identical(attrib.as.set=FALSE) now works correctly with data frames with default row names (Thanks to Charlie Gao's PR#18179).
txtProgressBar() now enforces a non-zero width for argument char, without which no progress can be visible.
dimnames(table(d)) is more consistent in the case where d is a list with a single component, thanks to Thomas Soeiro's report to R-devel.

Further, table(d1, d2) now gives an error when d1 and d2 are data frames as suggested by Thomas in PR#18224.
Fix for drawing semi-transparent lines and fills on the native Windows graphics device (PR#18219 and PR#16694). Thanks to Nick Ray for helpful diagnosis on Bugzilla.
The deparser now wraps sub-expressions such as if(A) .. with parentheses when needed; thanks to Duncan Murdoch's PR#18232 and Lionel Henry's patches there.
remove.packages() no longer tries to uninstall Priority: base packages, thanks to a report and suggestions by Colin Fay in PR#18227.
win.metafile() now has xpinch and ypinch arguments so that the user can override Windows' (potentially wrong) guess at device dimensions.
x[i] and x[[i]] for non-integer i should now behave in all cases as always documented: the index used is equivalent to as.integer(i) unless that would overflow where trunc(i) is used instead; thanks to Suharto Anggono's report and patch proposals in PR#17977.
asOneSidedFormula() now associates the resulting formula with the global environment rather than the evaluation environment created for the call.
<bibentry>$name now matches the field name case-insensitively, consistent with bibentry() creation and the replacement method.
cbind() failed to detect some length mismatches with a mixture of time-series and non-time-series inputs.
The default LaTeX style file ‘Sweave.sty’ used by the RweaveLatex driver no longer loads the obsolete ‘⁠ae⁠’ package; thanks to a report by Thomas Soeiro in PR#18271. Furthermore, it now skips ‘⁠\usepackage[T1]{fontenc}⁠’ for engines other than pdfTeX (if detected) or if the new ‘⁠[nofontenc]⁠’ option is used.
smooth.spline() now stores its logical cv argument more safely, fixing a rare bug when printing, and also stores n.
smooth.spline(x,y,*) now computes the cv.crit statistic correctly, also when is.unsorted(x), fixing PR#18294.
The data.frame method of rbind() now warns when binding not-wholly-recycling vectors, by analogy to the default method (for matrices).
setAs() finds the correct class for name to when multiple packages define a class with that name. Thanks to Gabor Csardi for the report.
Fix for detaching a package when two classes of the same name are present in method signatures for the same generic. Thanks to Gabor Csardi for the report.
match.arg("", c("", "a", "B")) gives a better error message, in part from PR#17959, thanks to Elin Waring.
R CMD Sweave --clean no longer removes pre-existing files or subdirectories (PR#18242).
The quartz() device no longer splits polylines into subpaths. That has caused narrowly-spaced lines with many points to always look solid even when dashed line type was used due to dash phase restarts.
Deparsing constructs such as quote(1 + `!`(2) + 3) works again as before R 3.5.0, thanks to the report and patch in PR#18284 by Suharto Anggono.
as.list(f) for a factor f now keeps names(f), fixing PR#18309.
qbeta(.001, .9, .009) and analogous qf() calls now return a correct value instead of NaN or wrongly 1, all with a warning; thanks to the report by Ludger Goeminne in PR#18302.
plot.lm() failed to produce the plot of residuals vs. factor levels (i.e., which=5 when leverages are constant) for models with character predictors (PR#17840).
interaction.plot(..., xtick = TRUE) misplaced the x-axis line (PR#18305).
Not strictly fixing a bug, format()ing and print()ing of non-finite Date and POSIXt values NaN and \pmInf no longer show as NA but the respective string, e.g., Inf, for consistency with numeric vector's behaviour, fulfilling the wish of PR#18308.
R CMD check no longer runs test scripts generated from corresponding ‘.Rin’ files twice and now signals an ERROR if processing an ‘.Rin’ script fails.
tools::Rd2txt() used for plain-text help pages now renders ⁠\href⁠s (if tools::Rd2txt_options(showURLs = TRUE)) and ⁠\url⁠s with percent-encoding and standards-compliant delimiting style (angle brackets and no ‘⁠URL: ⁠’ prefix). ⁠\email⁠ is now rendered with a ‘⁠mailto:⁠’ prefix.

CHANGES IN R 4.1.3

NEW FEATURES

The default version of Bioconductor has been changed to 3.14. (This is used by setRepositories and the menus in GUIs.)

UTILITIES

R CMD check --as-cran has a workaround for a bug in versions of file up to at least 5.41 which mis-identify DBF files last changed in 2022 as executables.

C-LEVEL FACILITIES

The legacy S-compatibility macros SINGLE_* in ‘R_ext/Constants.h’ (included by ‘R.h’) are deprecated and will be removed in R 4.2.0.

BUG FIXES

Initialization of self-starting nls() models with initialization functions following the pre-R-4.1.0 API (without the ... argument) works again for now, with a deprecation warning.
Fixed quoting of ~autodetect~ in Java setting defaults to avoid inadvertent user lookup due to leading ~, reported in PR#18231 by Harold Gutch.
substr(., start, stop) <- v now treats negative stop values correctly. Reported with a patch in PR#18228 by Brodie Gaslam.
Subscripting an array x without dimnames by a length(dim(x))-column character matrix gave "random" non-sense, now an error; reported in PR#18244 by Mikael Jagan.
...names() now matches names(list(...)) closely, fixing PR#18247.
all.equal(*, scale = s) now works as intended when length(s) > 1, partly thanks to Michael Chirico's PR#18272.
print(x) for long vectors x now also works for named atomic vectors or lists and prints the correct number when reaching the getOption("max.print") limit; partly thanks to a report and proposal by Hugh Parsonage to the R-devel list.
all.equal(<selfStart>, *) no longer signals a deprecation warning.
reformulate(*, response=r) gives a helpful error message now when length(r) > 1, thanks to Bill Dunlap's PR#18281.
Modifying globalCallingHandlers inside withCallingHandlers() now works or fails correctly, thanks to Henrik Bengtsson's PR#18257.
hist(<Date>, breaks = "days") and hist(<POSIXt>, breaks = "secs") no longer fail for inputs of length 1.
qbeta(.001, .9, .009) and similar cases now converge correctly thanks to Ben Bolker's report in PR#17746.
window(x, start, end) no longer wrongly signals “'start' cannot be after 'end'”, fixing PR#17527 and PR#18291.
data() now checks that its (rarely used) list argument is a character vector – a couple of packages passed other types and gave incorrect results.
which() now checks its arr.ind argument is TRUE rather coercing to logical and taking the first element – which gave incorrect results in package code.
model.weights() and model.offset() more carefully extract their model components, thanks to Ben Bolker and Tim Taylor's R-devel post.
list.files(recursive = TRUE) now shows all broken symlinks (previously, some of them may have been omitted, PR#18296).

CHANGES IN R 4.1.2

C-LEVEL FACILITIES

The workaround in headers ‘R.h’ and ‘Rmath.h’ (using namespace std;) for the Oracle Developer Studio compiler is no longer needed now C++11 is required so has been removed. A couple more usages of log() (which should have been std::log()) with an int argument are reported on Solaris.
The undocumented limit of 4095 bytes on messages from the S-compatibility macros PROBLEM and MESSAGE is now documented and longer messages will be silently truncated rather than potentially causing segfaults.
If the R_NO_SEGV_HANDLER environment variable is non-empty, the signal handler for SEGV/ILL/BUS signals (which offers recovery user interface) is not set. This allows more reliable debugging of crashes that involve the console.

DEPRECATED AND DEFUNCT

The legacy S-compatibility macros PROBLEM, MESSAGE, ERROR, WARN, WARNING, RECOVER, ... are deprecated and will be hidden in R 4.2.0. R's native interface of Rf_error and Rf_warning has long been preferred.

BUG FIXES

.mapply(F, dots, .) no longer segfaults when dots is not a list and uses match.fun(F) as always documented; reported by Andrew Simmons in PR#18164.
hist(<Date>, ...) and hist(<POSIXt>, ...) no longer pass arguments for rect() (such as col and density) to axis(). (Thanks to Sebastian Meyer's PR#18171.)
⁠\Sexpr{ch}⁠ now preserves Encoding(ch). (Thanks to report and patch by Jeroen Ooms in PR#18152.)
Setting the RNG to "Marsaglia-Multicarry" e.g., by RNGkind(), now warns in more places, thanks to André Gillibert's report and patch in PR#18168.
gray(numeric(), alpha=1/2) no longer segfaults, fixing PR#18183, reported by Till Krenz.
Fixed dnbinom(x, size=<very_small>, .., log=TRUE) regression, reported by Martin Morgan.
as.Date.POSIXlt(x) now keeps names(x), thanks to Davis Vaughan's report and patch in PR#18188.
model.response() now strips an "AsIs" class typically, thanks to Duncan Murdoch's report and other discussants in PR#18190.
try() is considerably faster in case of an error and long call, as e.g., from some do.call(). Thanks to Alexander Kaever's suggestion posted to R-devel.
qqline(y = <object>) such as y=I(.), now works, see also PR#18190.
Non-integer mgp par() settings are now handled correctly in axis() and mtext(), thanks to Mikael Jagan and Duncan Murdoch's report and suggestion in PR#18194.
formatC(x) returns length zero character() now, rather than "" when x is of length zero, as documented, thanks to Davis Vaughan's post to R-devel.
removeSource(fn) now retains (other) attributes(fn).

CHANGES IN R 4.1.1

NEW FEATURES

require(pkg, quietly = TRUE) is quieter and in particular does not warn if the package is not found.

DEPRECATED AND DEFUNCT

Use of ‘⁠ftp://⁠’ URIs should be regarded as deprecated, with on-going support confined to method = "libcurl" and not routinely tested. (Nowadays no major browser supports them.)
The non-default method = "internal" is deprecated for ‘⁠http://⁠’ and ‘⁠ftp://⁠’ URIs for both download.file and url.
On Windows, method = "wininet" is deprecated for ‘⁠http://⁠’, ‘⁠https://⁠’ and ‘⁠ftp://⁠’ URIs for both download.file and url. (A warning is only given for ‘⁠ftp://⁠’.)

For ‘⁠ftp://⁠’ URIs the default method is now "libcurl" if available (which it is on CRAN builds).

method = "wininet" remains the default for ‘⁠http://⁠’ and ‘⁠https://⁠’ URIs but if libcurl is available, using method = "libcurl" is preferred.

INSTALLATION

make check now works also without a LaTeX installation. (Thanks to Sebastian Meyer's PR#18103.)

BUG FIXES

make check-devel works again in an R build configured with --without-recommended-packages.
qnbinom(p, size, mu) for large size/mu is correct now in a range of cases (PR#18095); similarly for the (size, prob) parametrization of the negative binomial. Also qpois() and qbinom() are better and or faster for extreme cases. The underlying C code has been modularized and is common to all four cases of discrete distributions.
gap.axis is now part of the axis() arguments which are passed from bxp(), and hence boxplot(). (Thanks to Martin Smith's report and suggestions in PR#18109.)
.First and .Last can again be set from the site profile.
seq.int(from, to, *) and seq.default(..) now work better in large range cases where from-to is infinite where the two boundaries are finite.
all.equal(x,y) now returns TRUE correctly also when several entries of abs(x) and abs(y) are close to .Machine$double.xmax, the largest finite numeric.
model.frame() now clears the object bit when removing the class attribute of a value via na.action (PR#18100).
charClass() now works with multi-character strings on Windows (PR#18104, fixed by Bill Dunlap).
encodeString() on Solaris now works again in Latin-1 encoding on characters represented differently in UTF-8. Support for surrogate pairs on Solaris has been improved.
file.show() on Windows now works with non-ASCII path names representable in the current native encoding (PR#18132).
Embedded R on Windows can now find R home directory via the registry even when installed only for the current user (PR#18135).
pretty(x) with finite x now returns finite values also in the case where the extreme x values are close in size to the maximal representable number .Machine$double.xmax.

Also, it's been tweaked for very small ranges and when a boundary is close (or equal) to zero; e.g., pretty(c(0,1e-317)) no longer has negative numbers, currently still warning about a very small range, and pretty(2^-(1024 - 2^-1/(c(24,10)))) is more accurate.
The error message for not finding vignette files when weaving has correct file sizes now. (Thanks to Sebastian Meyer's PR#18154.)
dnbinom(20, <large>, 1) now correctly gives 0, and similar cases are more accurate with underflow precaution. (Reported by Francisco Vera Alcivar in PR#18072.)

CHANGES IN R 4.1.0

FUTURE DIRECTIONS

It is planned that the 4.1.x series will be the last to support 32-bit Windows, with production of binary packages for that series continuing until early 2023.

SIGNIFICANT USER-VISIBLE CHANGES

Data set esoph in package datasets now provides the correct numbers of controls; previously it had the numbers of cases added to these. (Reported by Alexander Fowler in PR#17964.)

NEW FEATURES

‘⁠www.omegahat.net⁠’ is no longer one of the repositories known by default to setRepositories(). (Nowadays it only provides source packages and is often unavailable.)
Function package_dependencies() (in package tools) can now use different dependency types for direct and recursive dependencies.
The checking of the size of tarball in R CMD check --as-cran <pkg> may be tweaked via the new environment variable _R_CHECK_CRAN_INCOMING_TARBALL_THRESHOLD_, as suggested in PR#17777 by Jan Gorecki.
Using c() to combine a factor with other factors now gives a factor, an ordered factor when combining ordered factors with identical levels.
apply() gains a simplify argument to allow disabling of simplification of results.
The format() method for class "ftable" gets a new option justify. (Suggested by Thomas Soeiro.)
New ...names() utility. (Proposed by Neal Fultz in PR#17705.)
type.convert() now warns when its as.is argument is not specified, as the help file always said it should. In that case, the default is changed to TRUE in line with its change in read.table() (related to stringsAsFactors) in R 4.0.0.
When printing list arrays, classed objects are now shown via their format() value if this is a short enough character string, or by giving the first elements of their class vector and their length.
capabilities() gets new entry "Rprof" which is TRUE when R has been configured with the equivalent of --enable-R-profiling (as it is by default). (Related to Michael Orlitzky's report PR#17836.)
str(xS4) now also shows extraneous attributes of an S4 object xS4.
Rudimentary support for vi-style tags in rtags() and R CMD rtags has been added. (Based on a patch from Neal Fultz in PR#17214.)
checkRdContents() is now exported from tools; it and also checkDocFiles() have a new option chkInternal allowing to check Rd files marked with keyword "internal" as well. The latter can be activated for R CMD check via environment variable _R_CHECK_RD_INTERNAL_TOO_.
New functions numToBits() and numToInts() extend the raw conversion utilities to (double precision) numeric.
Functions URLencode() and URLdecode() in package utils now work on vectors of URIs. (Based on patch from Bob Rudis submitted with PR#17873.)
path.expand() can expand ‘⁠~user⁠’ on most Unix-alikes even when readline is not in use. It tries harder to expand ‘⁠~⁠’, for example should environment variable HOME be unset.
For HTML help (both dynamic and static), Rd file links to help pages in external packages are now treated as references to topics rather than file names, and fall back to a file link only if the topic is not found in the target package. The earlier rule which prioritized file names over topics can be restored by setting the environment variable _R_HELP_LINKS_TO_TOPICS_ to a false value.
c() now removes NULL arguments before dispatching to methods, thus simplifying the implementation of c() methods, but for back compatibility keeps NULL when it is the first argument. (From a report and patch proposal by Lionel Henry in PR#17900.)
Vectorize()'s result function's environment no longer keeps unneeded objects.
Function ...elt() now propagates visibility consistently with ..n. (Thanks to Lionel Henry's PR#17905.)
capture.output() no longer uses non-standard evaluation to evaluate its arguments. This makes evaluation of functions like parent.frame() more consistent. (Thanks to Lionel Henry's PR#17907.)
packBits(bits, type="double") now works as inverse of numToBits(). (Thanks to Bill Dunlap's proposal in PR#17914.)
curlGetHeaders() has two new arguments, timeout to specify the timeout for that call (overriding getOption("timeout")) and TLS to specify the minimum TLS protocol version to be used for https:// URIs (inter alia providing a means to check for sites using deprecated TLS versions 1.0 and 1.1).
For nls(), an optional constant scaleOffset may be added to the denominator of the relative offset convergence test for cases where the fit of a model is expected to be exact, thanks to a proposal by John Nash. nls(*, trace=TRUE) now also shows the convergence criterion.
Numeric differentiation via numericDeriv() gets new optional arguments eps and central, the latter for taking central divided differences. The latter can be activated for nls() via nls.control(nDcentral = TRUE).
nls() now passes the trace and control arguments to getInitial(), notably for all self-starting models, so these can also be fit in zero-noise situations via a scaleOffset. For this reason, the initial function of a selfStart model must now have ... in its argument list.
bquote(splice = TRUE) can now splice expression vectors with attributes: this makes it possible to splice the result of parse(keep.source = TRUE). (Report and patch provided by Lionel Henry in PR#17869.)
textConnection() gets an optional name argument.
get(), exists(), and get0() now signal an error if the first argument has length greater than 1. Previously additional elements were silently ignored. (Suggested by Antoine Fabri on R-devel.)
R now provides a shorthand notation for creating functions, e.g. \(x) x + 1 is parsed as function(x) x + 1.
R now provides a simple native forward pipe syntax |>. The simple form of the forward pipe inserts the left-hand side as the first argument in the right-hand side call. The pipe implementation as a syntax transformation was motivated by suggestions from Jim Hester and Lionel Henry.
all.equal(f, g) for functions now by default also compares their environment(.)s, notably via new all.equal method for class function. Comparison of nls() fits, e.g., may now need all.equal(m1, m2, check.environment = FALSE).
.libPaths() gets a new option include.site, allowing to not include the site library. (Thanks to Dario Strbenac's suggestion and Gabe Becker's PR#18016.)
Lithuanian translations are now available. (Thanks to Rimantas Žakauskas.)
names() now works for DOTSXP objects. On the other hand, in ‘R-lang’, the R language manual, we now warn against relying on the structure or even existence of such dot-dot-dot objects.
all.equal() no longer gives an error on DOTSXP objects.
capabilities("cairo") now applies only to the file-based devices as it is now possible (if very unusual) to build R with Cairo support for those but not for X11().
There is optional support for tracing the progress of loadNamespace() — see its help.
(Not Windows.) l10n_info() reports an additional element, the name of the encoding as reported by the OS (which may differ from the encoding part (if any) of the result from Sys.getlocale("LC_CTYPE")).
New function gregexec() which generalizes regexec() to find all disjoint matches and all substrings corresponding to parenthesized subexpressions of the given regular expression. (Contributed by Brodie Gaslam.)
New function charClass() in package utils to query the wide-character classification functions in use (such as iswprint).
The names of quantile()'s result no longer depend on the global getOption("digits"), but quantile() gets a new optional argument digits = 7 instead.
grep(), sub(), regexp and variants work considerably faster for long factors with few levels. (Thanks to Michael Chirico's PR#18063.)
Provide grouping of x11() graphics windows within a window manager such as Gnome or Unity; thanks to a patch by Ivan Krylov posted to R-devel.
The split() method for class data.frame now allows the f argument to be specified as a formula.
sprintf now warns on arguments unused by the format string.
New palettes "Rocket" and "Mako" for hcl.colors() (approximating palettes of the same name from the viridisLite package).

Contributed by Achim Zeileis.
The base environment and its namespace are now locked (so one can no longer add bindings to these or remove from these).
Rterm handling of multi-byte characters has been improved, allowing use of such characters when supported by the current locale.
Rterm now accepts ALT+ +xxxxxxxx sequences to enter Unicode characters as hex digits.
Environment variable LC_ALL on Windows now takes precedence over LC_CTYPE and variables for other supported categories, matching the POSIX behaviour.
duplicated() and anyDuplicated() are now optimized for integer and real vectors that are known to be sorted via the ALTREP framework. Contributed by Gabriel Becker via PR#17993.

GRAPHICS

The graphics engine version, R_GE_version, has been bumped to 14 and so packages that provide graphics devices should be reinstalled.
Graphics devices should now specify deviceVersion to indicate what version of the graphics engine they support.
Graphics devices can now specify deviceClip. If TRUE, the graphics engine will never perform any clipping of output itself.

The clipping that the graphics engine does perform (for both canClip = TRUE and canClip = FALSE) has been improved to avoid producing unnecessary artifacts in clipped output.
The grid package now allows gpar(fill) to be a linearGradient(), a radialGradient(), or a pattern(). The viewport(clip) can now also be a grob, which defines a clipping path, and there is a new viewport(mask) that can also be a grob, which defines a mask.

These new features are only supported so far on the Cairo-based graphics devices and on the pdf() device.
(Not Windows.) A warning is given when a Cairo-based type is specified for a png(), jpeg(), tiff() or bmp() device but Cairo is unsupported (so type = "Xlib" is tried instead).
grSoftVersion() now reports the versions of FreeType and FontConfig if they are used directly (not via Pango), as is most commonly done on macOS.

C-LEVEL FACILITIES

The standalone ‘libRmath’ math library and R's C API now provide log1pexp() again as documented, and gain log1mexp().

INSTALLATION on a UNIX-ALIKE

configure checks for a program pkgconf if program pkg-config is not found. These are now only looked for on the path (like almost all other programs) so if needed specify a full path to the command in PKG_CONFIG, for example in file ‘config.site’.
C99 function iswblank is required – it was last seen missing ca 2003 so the workaround has been removed.
There are new configure options --with-internal-iswxxxxx, --with-internal-towlower and --with-internal-wcwidth which allows the system functions for wide-character classification, case-switching and width (wcwidth and wcswidth) to be replaced by internal ones. The first has long been used on macOS, AIX (and Windows) but this enables it to be unselected there and selected for other platforms (it is the new default on Solaris). The second is new in this version of R and is selected by default on macOS and Solaris. The third has long been the default and remains so as it contains customizations for East Asian languages.

System versions of these functions are often minimally implemented (sometimes only for ASCII characters) and may not cover the full range of Unicode points: for example Solaris (and Windows) only cover the Basic Multilingual Plane.
Cairo installations without X11 are more likely to be detected by configure, when the file-based Cairo graphics devices will be available but not X11(type = "cairo").
There is a new configure option --with-static-cairo which is the default on macOS. This should be used when only static cairo (and where relevant, Pango) libraries are available.
Cairo-based graphics devices on platforms without Pango but with FreeType/FontConfig will make use of the latter for font selection.

LINK-TIME OPTIMIZATION on a UNIX-ALIKE

Configuring with flag --enable-lto=R now also uses LTO when installing the recommended packages.
R CMD INSTALL and R CMD SHLIB have a new flag --use-LTO to use LTO when compiling code, for use with R configured with --enable-lto=R. For R configured with --enable-lto, they have the new flag --no-use-LTO.

Packages can opt in or out of LTO compilation via a ‘⁠UseLTO⁠’ field in the ‘DESCRIPTION’ file. (As usual this can be overridden by the command-line flags.)

BUILDING R on Windows

for GCC \ge 8, FC_LEN_T is defined in ‘config.h’ and hence character lengths are passed from C to Fortran in inter alia BLAS and LAPACK calls.
There is a new text file ‘src/gnuwin32/README.compilation’, which outlines how C/Fortran code compilation is organized and documents new features:
- R can be built with Link-Time Optimization with a suitable compiler – doing so with GCC 9.2 showed several inconsistencies which have been corrected.
- There is support for cross-compiling the C and Fortran code in R and standard packages on suitable (Linux) platforms. This is mainly intended to allow developers to test later versions of compilers – for example using GCC 9.2 or 10.x has detected issues that GCC 8.3 in Rtools40 does not.
- There is experimental support for cross-building R packages with C, C++ and/or Fortran code.
The R installer can now be optionally built to support a single architecture (only 64-bit or only 32-bit).

PACKAGE INSTALLATION

The default C++ standard has been changed to C++14 where available (which it is on all currently checked platforms): if not (as before) C++11 is used if available otherwise C++ is not supported.

Packages which specify C++11 will still be installed using C++11.

C++14 compilers may give deprecation warnings, most often for std::random_shuffle (deprecated in C++14 and removed in C++17). Either specify C++11 (see ‘Writing R Extensions’) or modernize the code and if needed specify C++14. The latter has been supported since R 3.4.0 so the package's ‘DESCRIPTION’ would need to include something like
```
     Depends: R (>= 3.4)
```

PACKAGE INSTALLATION on Windows

R CMD INSTALL and R CMD SHLIB make use of their flag --use-LTO when the ‘⁠LTO_OPT⁠’ make macro is set in file ‘etc/${R_ARCH}/Makeconf’ or in a personal/site ‘Makevars’ file. (For details see ‘Writing R Extensions’ §4.5.)

This provides a valuable check on code consistency. It does work with GCC 8.3 as in Rtools40, but that does not detect everything the CRAN checks with current GCC do.

PACKAGE INSTALLATION on macOS

The default personal library directory on builds with --enable-aqua (including CRAN builds) now differs by CPU type, one of
```
      ~/Library/R/x86_64/x.y/library
      ~/Library/R/arm64/x.y/library
```
This uses the CPU type R (and hence the packages) were built for, so when a ‘⁠x86_64⁠’ build of R is run under Rosetta emulation on an ‘⁠arm64⁠’ Mac, the first is used.

UTILITIES

R CMD check can now scan package functions for bogus return statements, which were possibly intended as return() calls (wish of PR#17180, patch by Sebastian Meyer). This check can be activated via the new environment variable _R_CHECK_BOGUS_RETURN_, true for --as-cran.
R CMD build omits tarballs and binaries of previous builds from the top-level package directory. (PR#17828, patch by Sebastian Meyer.)
R CMD check now runs sanity checks on the use of ‘⁠LazyData⁠’, for example that a ‘data’ directory is present and that ‘⁠LazyDataCompression⁠’ is not specified without ‘⁠LazyData⁠’ and has a documented value. For packages with large LazyData databases without specifying ‘⁠LazyDataCompression⁠’, there is a reference to the code given in ‘Writing R Extensions’ §1.1.6 to test the choice of compression (as in all the CRAN packages tested a non-default method was preferred).
R CMD build removes ‘⁠LazyData⁠’ and ‘⁠LazyDataCompression⁠’ fields from the ‘DESCRIPTION’ file of packages without a ‘data’ directory.

ENCODING-RELATED CHANGES

The parser now treats ‘⁠\Unnnnnnnn⁠’ escapes larger than the upper limit for Unicode points (‘⁠\U10FFFF⁠’) as an error as they cannot be represented by valid UTF-8.

Where such escapes are used for outputting non-printable (including unassigned) characters, 6 hex digits are used (rather than 8 with leading zeros). For clarity, braces are used, for example ‘⁠\U{0effff}⁠’.
The parser now looks for non-ASCII spaces on Solaris (as previously on most other OSes).
There are warnings (including from the parser) on the use of unpaired surrogate Unicode points such as ‘⁠\uD834⁠’. (These cannot be converted to valid UTF-8.)
Functions nchar(), tolower(), toupper() and chartr() and those using regular expressions have more support for inputs with a marked Latin-1 encoding.
The character-classification functions used (by default) to replace the system iswxxxxx functions on Windows, macOS and AIX have been updated to Unicode 13.0.0.

The character-width tables have been updated to include new assignments in Unicode 13.0.0. This included treating all control characters as having zero width.
The code for evaluating default (extended) regular expressions now uses the same character-classification functions as the rest of R (previously they differed on Windows, macOS and AIX).
There is a build-time option to replace the system's wide-character wctrans C function by tables shipped with R: use configure option --with-internal-towlower or (on Windows) ‘⁠-DUSE_RI18N_CASE⁠’ in ‘⁠CFLAGS⁠’ when building R. This may be needed to allow tolower() and toupper() to work with Unicode characters beyond the Basic Multilingual Plane where not supported by system functions (e.g. on Solaris where it is the new default).
R is more careful when truncating UTF-8 and other multi-byte strings that are too long to be printed, passed to the system or libraries or placed into an internal buffer. Truncation will no longer produce incomplete multibyte characters.

DEPRECATED AND DEFUNCT

Function plclust() from the package stats and package.dependencies(), pkgDepends(), getDepList(), installFoundDepends(), and vignetteDepends() from package tools are defunct.
Defunct functions checkNEWS() and readNEWS() from package tools and CRAN.packages() from utils have been removed.
R CMD config CXXCPP is defunct (it was deprecated in R 3.6.2).
parallel::detectCores() drops support for IRIX (retired in 2013).
The LINPACK argument to chol.default(), chol2inv(), solve.default() and svd() has been defunct since R 3.1.0. It was silently ignored up to R 4.0.3 but now gives an error.
Subsetting/indexing, such as ddd[*] or ddd$x on a DOTSXP (dot-dot-dot) object ddd has been disabled; it worked by accident only and was undocumented.

BUG FIXES

Many more C-level allocations (mainly by malloc and strdup) are checked for success with suitable alternative actions.
Bug fix for replayPlot(); this was turning off graphics engine display list recording if a recorded plot was replayed in the same session. The impact of the bug became visible if resize the device after replay OR if attempted another savePlot() after replay (empty display list means empty screen on resize or empty saved plot).
R CMD check etc now warn when a package exports non-existing S4 classes or methods, also in case of no “methods” presence. (Reported by Alex Bertram; reproducible example and patch by Sebastian Meyer in PR#16662.)
boxplot() now also accepts calls for labels such as ylab, the same as plot(). (Reported by Marius Hofert.)
The help page for xtabs() now correctly states that addNA is setting na.action = na.pass among others. (Reported as PR#17770 by Thomas Soeiro.)
The R CMD check <pkg> gives a longer and more comprehensible message when ‘DESCRIPTION’ misses dependencies, e.g., in Imports:. (Thanks to the contributors of PR#17179.)
update.default() now calls the generic update() on the formula to work correctly for models with extended formulas. (As reported and suggested by Neal Fultz in PR#17865.)
The horizontal position of leaves in a dendrogram is now correct also with center = FALSE. (PR#14938, patch from Sebastian Meyer.)
all.equal.POSIXt() no longer warns about and subsequently ignores inconsistent "tzone" attributes, but describes the difference in its return value (PR#17277). This check can be disabled via the new argument check.tzone = FALSE as suggested by Sebastian Meyer.
as.POSIXct() now populates the "tzone" attribute from its tz argument when x is a logical vector consisting entirely of NA values.
x[[2^31]] <- v now works. (Thanks to the report and patch by Suharto Anggono in PR#17330.)
In log-scale graphics, axis() ticks and label positions are now computed more carefully and symmetrically in their range, typically providing more ticks, fulfilling wishes in PR#17936. The change really corresponds to an improved axisTicks() (package grDevices), potentially influencing grid and lattice, for example.
qnorm(<very large negative>, log.p=TRUE) is now correct to at least five digits where it was catastrophically wrong, previously.
sum(df) and similar "Summary"- and "Math"-group member functions now work for data frames df with logical columns, notably also of zero rows. (Reported to R-devel by Martin “b706”.)
unsplit() had trouble with tibbles due to unsound use of rep(NA, len)-indexing, which should use NA_integer_ (Reported to R-devel by Mario Annau.)
pnorm(x, log.p = TRUE) underflows to -Inf slightly later.
show(<hidden S4 generic>) prints better and without quotes for non-hidden S4 generics.
read.table() and relatives treated an "NA" column name as missing when check.names = FALSE PR#18007.
Parsing strings containing UTF-16 surrogate pairs such as "\uD834\uDD1E" works better on some (uncommon) platforms. sprintf("%X", utf8ToInt("\uD834\uDD1E")) should now give "1D11E" on all platforms.
identical(x,y) is no longer true for differing DOTSXP objects, fixing PR#18032.
str() now works correctly for DOTSXP and related exotics, even when these are doomed.

Additionally, it no longer fails for lists with a class and “irregular” method definitions such that e.g. lapply(*) will necessarily fail, as currently for different igraph objects.
Message translation domains, e.g., for errors and warnings, are now correctly determined also when e.g., a base function is called from “top-level” function (i.e., defined in globalenv()), thanks to a patch from Joris Goosen fixing PR#17998.
Too long lines in environment files (e.g., ‘Renviron’) no longer crash R. This limit has been increased to 100,000 bytes. (PR#18001.)
There is a further workaround for FreeType giving incorrect italic font faces with cairo-based graphics devices on macOS.
add_datalist(*, force = TRUE) (from package tools) now actually updates an existing ‘data/datalist’ file for new content. (Thanks to a report and patch by Sebastian Meyer in PR#18048.)
cut.Date() and cut.POSIXt() could produce an empty last interval for breaks = "months" or breaks = "years". (Reported as PR#18053 by Christopher Carbone.)
Detection of the encoding of ‘regular’ macOS locales such as ‘⁠en_US⁠’ (which is UTF-8) had been broken by a macOS change: fortunately these are now rarely used with ‘⁠en_US.UTF-8⁠’ being preferred.
sub() and gsub(pattern, repl, x, *) now keep attributes of x such as names() also when pattern is NA (PR#18079).
Time differences ("difftime" objects) get a replacement and a rep() method to keep "units" consistent. (Thanks to a report and patch by Nicolas Bennett in PR#18066.)
The ⁠\RdOpts⁠ macro, setting defaults for ⁠\Sexpr⁠ options in an Rd file, had been ineffective since R 2.12.0: it now works again. (Thanks to a report and patch by Sebastian Meyer in PR#18073.)
mclapply and pvec no longer accidentally terminate parallel processes started before by mcparallel or related calls in package parallel (PR#18078).
grep and other functions for evaluating (extended) regular expressions handle in Unicode also strings not explicitly flagged UTF-8, but flagged native when running in UTF-8 locale.
Fixed a crash in fifo implementation on Windows (PR#18031).
Binary mode in fifo on Windows is now properly detected from argument open (PR#15600, PR#18031).

CHANGES IN R 4.0.5

BUG FIXES

The change to the internal table in R 4.0.4 for iswprint has been reverted: it contained some errors in printability of ‘East Asian’ characters.
For packages using ‘⁠LazyData⁠’, R CMD build ignored the --resave-data option and the ‘⁠BuildResaveData⁠’ field of the ‘DESCRIPTION’ file (in R versions 4.0.0 to 4.0.4).

CHANGES IN R 4.0.4

NEW FEATURES

File ‘share/texmf/tex/latex/jss.cls’ has been updated to work with LaTeX versions since Oct 2020.
Unicode character width tables (as used by nchar(, type = "w")) have been updated to Unicode 12.1 by Brodie Gaslam (PR#17781), including many emoji.
The internal table for iswprint (used on Windows, macOS and AIX) has been updated to include many recent Unicode characters.

INSTALLATION on a UNIX-ALIKE

If an external BLAS is specified by --with-blas=foo or via environment variable BLAS_LIBS is not found, this is now a configuration error. The previous behaviour was not clear from the documentation: it was to continue the search as if --with-blas=yes was specified.

BUG FIXES

all.equal(x,y) now “sees” the two different NAs in factors, thanks to Bill Dunlap and others in PR#17897.
(~ NULL)[1] and similar formula subsetting now works, thanks to a report and patch by Henrik Bengtsson in PR#17935. Additionally, subsetting leaving an empty formula now works too, thanks to suggestions by Suharto Anggono.
.traceback(n) keeps source references again, as before R 4.0.0, fixing a regression; introduced by the PR#17580, reported including two patch proposals by Brodie Gaslam.
unlist(plst, recursive=FALSE) no longer drops content for pairlists with list components, thanks to the report and patch by Suharto Anggono in PR#17950.
iconvlist() now also works on MUSL based (Linux) systems, from a report and patch suggestion by Wesley Chan in PR#17970.
round() and signif() no longer tolerate wrong argument names, notably in 1-argument calls; reported by Shane Mueller on R-devel (mailing list); later reported as PR#17976.
.Machine has longdouble.* elements only if capabilities("long.double") is true, as documented. (Previously they were included if the platform had long double identical to double, as ARM does.)
p.adjust(numeric(), n=0) now works, fixing PR#18002.
identical(x,y) no longer prints "Unknown Type .." for typeof(x) == "..." objects.
Fix (auto-)print()ing of named complex vectors, see PR#17868 and PR#18019.
all.equal(<language>, <...>) now works, fixing PR#18029.
as.data.frame.list(L, row.names=NULL) now behaves in line with data.frame(), disregarding names of components of L, fixing PR#18034, reported by Kevin Tappe.
checkRdaFiles(ff)$version is now correct also when ff contains files of different versions, thanks to a report and patch from Sebastian Meyer in PR#18041.
macOS: Quartz device live drawing could fail (no plot is shown) if the system changes the drawing context after view update (often the case since macOS Big Sur). System log may show "CGContextDelegateCreateForContext: invalid context" error.

CHANGES IN R 4.0.3

NEW FEATURES

On platforms using configure option --with-internal-tzcode, additional values "internal" and (on macOS only) "macOS" are accepted for the environment variable TZDIR. (See ?TZDIR.)

On macOS, "macOS" is used by default if the system timezone database is a newer version than that in the R installation.
When install.packages(type = "source") fails to find a package in a repository it mentions package versions which are excluded by their R version requirement and links to hints on why a package might not be found.
The default value for options("timeout") can be set from environment variable R_DEFAULT_INTERNET_TIMEOUT, still defaulting to 60 (seconds) if that is not set or invalid.

This may be needed when child R processes are doing downloads, for example during the installation of source packages which download jars or other forms of data.

LINK-TIME OPTIMIZATION on a UNIX-ALIKE

There is now support for parallelized Link-Time Optimization (LTO) with GCC and for ‘thin’ LTO with clang via setting the ‘⁠LTO⁠’ macro.
There is support for setting a different LTO flag for the Fortran compiler, including to empty when mixing clang and gfortran (as on macOS). See file ‘config.site’.
There is a new ‘⁠LTO_LD⁠’ macro to set linker options for LTO compilation, for example to select an alternative linker or to parallelize thin LTO.

DEPRECATED AND DEFUNCT

The LINPACK argument to chol.default(), chol2inv(), solve.default() and svd() has been defunct since R 3.1.0. Using it now gives a warning which will become an error in R 4.1.0.

BUG FIXES

The code mitigating stack overflow with PCRE regexps on very long strings is enabled for PCRE2 < 10.30 also when JIT is enabled, since stack overflows have been seen in that case.
Fix to correctly show the group labels in dotchart() (which where lost in the ylab improvement for R 4.0.0).
addmargins(*, ..) now also works when fn() is a local function, thanks to bug report and patch PR#17124 from Alex Bertram.
rank(x) and hence sort(x) now work when x is an object (as per is.object(x)) of type "raw" and provides a valid `[` method, e.g., for gmp::as.bigz(.) numbers.
chisq.test(*, simulate.p.value=TRUE) and r2dtable() now work correctly for large table entries (in the millions). Reported by Sebastian Meyer and investigated by more helpers in PR#16184.
Low-level socket read/write operations have been fixed to correctly signal communication errors. Previously, such errors could lead to a segfault due to invalid memory access. Reported and debugged by Dmitriy Selivanov in PR#17850.
quantile(x, pr) works more consistently for pr values slightly outside [0,1], thanks to Suharto Anggono's PR#17891.

Further, quantile(x, prN, names=FALSE) now works even when prN contains NAs, thanks to Anggono's PR#17892. Ditto for ordered factors or Date objects when type = 1 or 3, thanks to PR#17899.
Internet access based on libcurl, including curlGetHeaders(), was not respecting the "timeout" option. If this causes unanticipated timeouts, consider increasing the default by setting R_DEFAULT_INTERNET_TIMEOUT.
as.Date(<char>) now also works with an initial "", thanks to Michael Chirico's PR#17909.
isS3stdGeneric(f) now detects an S3 generic also when it is trace()d, thanks to Gabe Becker's PR#17917.
R_allocLD() has been fixed to return memory aligned for long double type PR#16534.
fisher.test() no longer segfaults when called again after its internal stack has been exceeded PR#17904.
Accessing a long vector represented by a compact integer sequence no longer segfaults (reported and debugged by Hugh Parsonage).
duplicated() now works also for strings with multiple encodings inside a single vector PR#17809.
phyper(11, 15, 0, 12, log.p=TRUE) no longer gives NaN; reported as PR#17271 by Alexey Stukalov.
Fix incorrect calculation in logLik.nls() PR#16100, patch from Sebastian Meyer.
A very old bug could cause a segfault in model.matrix() when terms involved logical variables. Part of PR#17879.
model.frame.default() allowed data = 1, leading to involuntary variable capture (rest of PR#17879).
tar() no longer skips non-directory files, thanks to a patch by Sebastian Meyer, fixing the remaining part of PR#16716.

CHANGES IN R 4.0.2

UTILITIES

R CMD check skips vignette re-building (with a warning) if the ‘⁠VignetteBuilder⁠’ package(s) are not available.

BUG FIXES

Paths with non-ASCII characters caused problems for package loading on Windows PR#17833.
Using tcltk widgets no longer crashes R on Windows.
source(*, echo=TRUE) no longer fails in some cases with empty lines; reported by Bill Dunlap in PR#17769.
on.exit() now correctly matches named arguments, thanks to PR#17815 (including patch) by Brodie Gaslam.
regexpr(*, perl=TRUE) no longer returns incorrect positions into text containing characters outside of the Unicode Basic Multilingual Plane on Windows.

CHANGES IN R 4.0.1

NEW FEATURES

paste() and paste0() gain a new optional argument recycle0. When set to true, zero-length arguments are recycled leading to character(0) after the sep-concatenation, i.e., to the empty string "" if collapse is a string and to the zero-length value character(0) when collapse = NULL.

A package whose code uses this should depend on ‘⁠R (>= 4.0.1)⁠’.
The summary(<warnings>) method now maps the counts correctly to the warning messages.

BUG FIXES

aov(frml, ...) now also works where the formula deparses to more than 500 characters, thanks to a report and patch proposal by Jan Hauffa.
Fix a dozen places (code, examples) as Sys.setlocale() returns the new rather than the previous setting.
Fix for adding two complex grid units via sum(). Thanks to Gu Zuguang for the report and Thomas Lin Pedersen for the patch.
Fix parallel::mclapply(..., mc.preschedule=FALSE) to handle raw vector results correctly. PR#17779
Computing the base value, i.e., 2, “everywhere”, now uses FLT_RADIX, as the original ‘machar’ code looped indefinitely on the ppc64 architecture for the longdouble case.
In R 4.0.0, sort.list(x) when is.object(x) was true, e.g., for x <- I(letters), was accidentally using method = "radix". Consequently, e.g., merge(<data.frame>) was much slower than previously; reported in PR#17794.
plot(y ~ x, ylab = quote(y[i])) now works, as e.g., for xlab; related to PR#10525.
parallel::detect.cores(all.tests = TRUE) tries a matching OS name before the other tests (which were intended only for unknown OSes).
Parse data for raw strings is now recorded correctly. Reported by Gabor Csardi.

CHANGES IN R 4.0.0

SIGNIFICANT USER-VISIBLE CHANGES

Packages need to be (re-)installed under this version (4.0.0) of R.
matrix objects now also inherit from class "array", so e.g., class(diag(1)) is c("matrix", "array"). This invalidates code incorrectly assuming that class(matrix_obj)) has length one.

S3 methods for class "array" are now dispatched for matrix objects.
There is a new syntax for specifying raw character constants similar to the one used in C++: r"(...)" with ... any character sequence not containing the sequence ‘⁠)"⁠’. This makes it easier to write strings that contain backslashes or both single and double quotes. For more details see ?Quotes.
R now uses a ‘⁠stringsAsFactors = FALSE⁠’ default, and hence by default no longer converts strings to factors in calls to data.frame() and read.table().

A large number of packages relied on the previous behaviour and so have needed/will need updating.
The plot() S3 generic function is now in package base rather than package graphics, as it is reasonable to have methods that do not use the graphics package. The generic is currently re-exported from the graphics namespace to allow packages importing it from there to continue working, but this may change in future.

Packages which define S4 generics for plot() should be re-installed and package code using such generics from other packages needs to ensure that they are imported rather than rely on their being looked for on the search path (as in a namespace, the base namespace has precedence over the search path).

REFERENCE COUNTING

Reference counting is now used instead of the NAMED mechanism for determining when objects can be safely mutated in base C code. This reduces the need for copying in some cases and should allow further optimizations in the future. It should help make the internal code easier to maintain.

This change is expected to have almost no impact on packages using supported coding practices in their C/C++ code.

MIGRATION TO PCRE2

This version of R is built against the PCRE2 library for Perl-like regular expressions, if available. (On non-Windows platforms PCRE1 can optionally be used if PCRE2 is not available at build time.) The version of PCRE in use can be obtained via extSoftVersion(): PCRE1 (formerly known as ‘PCRE’) has versions <= 8, PCRE2 versions >= 10.
Making PCRE2 available when building R from source is strongly recommended (preferably version 10.30 or later) as PCRE1 is no longer developed: version 8.44 is ‘likely to be the final release’.
PCRE2 reports errors for some regular expressions that were accepted by PCRE1. A hyphen now has to be escaped in a character class to be interpreted as a literal (unless first or last in the class definition). ‘⁠\R⁠’, ‘⁠\B⁠’ and ‘⁠\X⁠’ are no longer allowed in character classes (PCRE1 treated these as literals).
Option PCRE_study is no longer used with PCRE2, and is reported as FALSE when that is in use.

NEW FEATURES

assertError() and assertWarning() (in package tools) can now check for specific error or warning classes via the new optional second argument classes (which is not back compatible with previous use of an unnamed second argument).
DF2formula(), the utility for the data frame method of formula(), now works without parsing and explicit evaluation, starting from Suharto Anggono's suggestion in PR#17555.
approxfun() and approx() gain a new argument na.rm defaulting to true. If set to false, missing y values now propagate into the interpolated values.
Long vectors are now supported as the seq argument of a for() loop.
str(x) gets a new deparse.lines option with a default to speed it up when x is a large call object.
The internal traceback object produced when an error is signalled (.Traceback), now contains the calls rather than the deparse()d calls, deferring the deparsing to the user-level functions .traceback() and traceback(). This fulfils the wish of PR#17580, reported including two patch proposals by Brodie Gaslam.
data.matrix() now converts character columns to factors and from this to integers.
package.skeleton() now explicitly lists all exports in the ‘NAMESPACE’ file.
New function .S3method() to register S3 methods in R scripts.
file.path() has some support for file paths not in the session encoding, e.g. with UTF-8 inputs in a non-UTF-8 locale the output is marked as UTF-8.
Most functions with file-path inputs will give an explicit error if a file-path input in a marked encoding cannot be translated (to the native encoding or in some cases on Windows to UTF-8), rather than translate to a different file path using escapes. Some (such as dir.exists(), file.exists(), file.access(), file.info(), list.files(), normalizePath() and path.expand()) treat this like any other non-existent file, often with a warning.
There is a new help document accessed by help("file path encoding") detailing how file paths with marked encodings are handled.
New function list2DF() for creating data frames from lists of variables.
iconv() has a new option sub = "Unicode" to translate UTF-8 input invalid in the ‘⁠to⁠’ encoding using ‘⁠<U+xxxx>⁠’ escapes.
There is a new function infoRDS() providing information about the serialization format of a serialized object.
S3 method lookup now by default skips the elements of the search path between the global and base environments.
Added an argument add_datalist(*, small.size = 0) to allow the creation of a ‘data/datalist’ file even when the total size of the data sets is small.
The backquote function bquote() has a new argument splice to enable splicing a computed list of values into an expression, like ,@ in LISP's backquote.
The formula interface to t.test() and wilcox.test() has been extended to handle one-sample and paired tests.
The palette() function has a new default set of colours (which are less saturated and have better accessibility properties). There are also some new built-in palettes, which are listed by the new palette.pals() function. These include the old default palette under the name "R3". Finally, the new palette.colors() function allows a subset of colours to be selected from any of the built-in palettes.
n2mfrow() gains an option asp = 1 to specify the aspect ratio, fulfilling the wish and extending the proposal of Michael Chirico in PR#17648.
For head(x, n) and tail() the default and other S3 methods notably for vector n, e.g. to get a “corner” of a matrix, has been extended to array's of higher dimension thanks to the patch proposal by Gabe Becker in PR#17652. Consequently, optional argument addrownums is deprecated and replaced by the (more general) argument keepnums. An invalid second argument n now leads to typically more easily readable error messages.
New function .class2() provides the full character vector of class names used for S3 method dispatch.
Printing methods(..) now uses a new format() method.
sort.list(x) now works for non-atomic objects x and method = "auto" (the default) or "radix" in cases order(x) works, typically via a xtfrm() method.
Where they are available, writeBin() allows long vectors.
New function deparse1() produces one string, wrapping deparse(), to be used typically in deparse1(substitute(*)), e.g., to fix PR#17671.
wilcox.test() enhancements: In the (non-paired) two-sample case, Inf values are treated as very large for robustness consistency. If exact computations are used, the result now has "exact" in the method element of its return value. New arguments tol.root and digits.rank where the latter may be used for stability to treat very close numbers as ties.
readBin() and writeBin() now report an error for an invalid endian value. The affected code needs to be fixed with care as the old undocumented behavior was to swap endianness in such cases.
sequence() is now an S3 generic with an internally implemented default method, and gains arguments to generate more complex sequences. Based on code from the S4Vectors Bioconductor package and the advice of Hervé Pagès.
print()'s default method and many other methods (by calling the default eventually and passing ...) now make use of a new optional width argument, avoiding the need for the user to set and reset options("width").
memDecompress() supports the RFC 1952 format (e.g. in-memory copies of gzip-compressed files) as well as RFC 1950.
memCompress() and memDecompress() support long raw vectors for types "gzip" and "zx".
sweep() and slice.index() can now use names of dimnames for their MARGIN argument (apply has had this for almost a decade).
New function proportions() and marginSums(). These should replace the unfortunately named prop.table() and margin.table(). They are drop-in replacements, but also add named-margin functionality. The old function names are retained as aliases for back-compatibility.
Functions rbinom(), rgeom(), rhyper(), rpois(), rnbinom(), rsignrank() and rwilcox() which have returned integer since R 3.0.0 and hence NA when the numbers would have been outside the integer range, now return double vectors (without NAs, typically) in these cases.
matplot(x,y) (and hence matlines() and matpoints()) now call the corresponding methods of plot() and lines(), e.g, when x is a "Date" or "POSIXct" object; prompted by Spencer Graves' suggestion.
stopifnot() now allows customizing error messages via argument names, thanks to a patch proposal by Neal Fultz in PR#17688.
unlink() gains a new argument expand to disable wildcard and tilde expansion. Elements of x of value "~" are now ignored.
mle() in the stats4 package has had its interface extended so that arguments to the negative log-likelihood function can be one or more vectors, with similar conventions applying to bounds, start values, and parameter values to be kept fixed. This required a minor extension to class "mle", so saved objects from earlier versions may need to be recomputed.
The default for pdf() is now useDingbats = FALSE.
The default fill colour for hist() and boxplot() is now col = "lightgray".
The default order of the levels on the y-axis for spineplot() and cdplot() has been reversed.
If the R_ALWAYS_INSTALL_TESTS environment variable is set to a true value, R CMD INSTALL behaves as if the --install-tests option is always specified. Thanks to Reinhold Koch for the suggestion.
New function R_user_dir() in package tools suggests paths appropriate for storing R-related user-specific data, configuration and cache files.
capabilities() gains a new logical option Xchk to avoid warnings about X11-related capabilities.
The internal implementation of grid units has changed, but the only visible effects at user-level should be
- a slightly different print format for some units (especially unit arithmetic),
- faster performance (for unit operations) and
- two new functions unitType() and unit.psum().
Based on code contributed by Thomas Lin Pedersen.
When internal dispatch for rep.int() and rep_len() fails, there is an attempt to dispatch on the equivalent call to rep().
Object .Machine now contains new longdouble.* entries (when R uses long doubles internally).
news() has been enhanced to cover the news on R 3.x and 2.x.
For consistency, N <- NULL; N[[1]] <- val now turns N into a list also when val) has length one. This enables dimnames(r1)[[1]] <- "R1" for a 1-row matrix r1, fixing PR#17719 reported by Serguei Sokol.
deparse(..), dump(..), and dput(x, control = "all") now include control option "digits17" which typically ensures 1:1 invertibility. New option control = "exact" ensures numeric exact invertibility via "hexNumeric".
When loading data sets via read.table(), data() now uses ‘⁠LC_COLLATE=C⁠’ to ensure locale-independent results for possible string-to-factor conversions.
A server socket connection, a new connection type representing a listening server socket, is created via serverSocket() and can accept multiple socket connections via socketAccept().
New function socketTimeout() changes the connection timeout of a socket connection.
The time needed to start a homogeneous ‘⁠PSOCK⁠’ cluster on ‘⁠localhost⁠’ with many nodes has been significantly reduced (package parallel).
New globalCallingHandlers() function to establish global condition handlers. This allows registering default handlers for specific condition classes. Developed in collaboration with Lionel Henry.
New function tryInvokeRestart() to invoke a specified restart if one is available and return without signaling an error if no such restart is found. Contributed by Lionel Henry in PR#17598.
str(x) now shows the length of attributes in some cases for a data frame x.
Rprof() gains a new argument filter.callframes to request that intervening call frames due to lazy evaluation or explicit eval() calls be omitted from the recorded profile data. Contributed by Lionel Henry in PR#17595.
The handling of ${FOO-bar} and ${FOO:-bar} in ‘Renviron’ files now follows POSIX shells (at least on a Unix-alike), so the first treats empty environment variables as set and the second does not. Previously both ignored empty variables. There are several uses of the first form in ‘etc/Renviron’.
New classes argument for suppressWarnings() and suppressMessages() to selectively suppress only warnings or messages that inherit from particular classes. Based on patch from Lionel Henry submitted with PR#17619.
New function activeBindingFunction() retrieves the function of an active binding.
New "cairoFT" and "pango" components in the output of grSoftVersion().
New argument symbolfamily in cairo-based graphics devices and new function cairoSymbolFont() that can be used to provide the value for that argument.

Windows

Rterm now works also when invoked from MSYS2 terminals. Line editing is possible when command winpty is installed.
normalizePath() now resolves symbolic links and normalizes case of long names of path elements in case-insensitive folders (PR#17165).
md5sum() supports UTF-8 file names with characters that cannot be translated to the native encoding (PR#17633).
Rterm gains a new option --workspace to specify the workspace to be restored. This allows equals to be part of the name when opening via Windows file associations (reported by Christian Asseburg).
Rterm now accepts ALT+xxx sequences also with NumLock on. Tilde can be pasted with an Italian keyboard (PR#17679).
R falls back to copying when junction creation fails during package checking (patch from Duncan Murdoch).

DEPRECATED AND DEFUNCT

Make macro ‘⁠F77_VISIBILITY⁠’ has been removed and replaced by ‘⁠F_VISIBILITY⁠’.
Make macros ‘⁠F77⁠’, ‘⁠FCPIFCPLAGS⁠’ and ‘⁠SHLIB_OPENMP_FCFLAGS⁠’ have been removed and replaced by ‘⁠FC⁠’, ‘⁠FPICFLAGS⁠’ and ‘⁠SHLIB_OPENMP_FFLAGS⁠’ respectively. (Most make programs will set ‘⁠F77⁠’ to the value of ‘⁠FC⁠’, which is set for package compilation. But portable code should not rely on this.)
The deprecated support for specifying C++98 for package installation has been removed.
R CMD config no longer knows about the unused settings ‘⁠F77⁠’ and ‘⁠FCPIFCPLAGS⁠’, nor ‘⁠CXX98⁠’ and similar.
Either PCRE2 or PCRE1 >= 8.32 (Nov 2012) is required: the deprecated provision for 8.20–8.31 has been removed.
Defunct functions mem.limits(), .readRDS(), .saveRDS(), .find.package(), and .path.package() from package base and allGenerics(), getAccess(), getAllMethods(), getClassName(), getClassPackage(), getExtends(), getProperties(), getPrototype(), getSubclasses(), getVirtual(), mlistMetaName(), removeMethodsObject(), seemsS4Object(), traceOff(), and traceOn() from methods have been removed.

C-LEVEL FACILITIES

installChar is now remapped in ‘Rinternals.h’ to installTrChar, of which it has been a wrapper since R 3.6.0. Neither are part of the API, but packages using installChar can replace it if they depend on ‘⁠R >= 3.6.2⁠’.
Header ‘R_ext/Print.h’ defines ‘⁠R_USE_C99_IN_CXX⁠’ and hence exposes Rvprintf and REvprintf if used with a C++11 (or later) compiler.
There are new Fortran subroutines dblepr1, realpr1 and intpr1 to print a scalar variable (gfortran 10 enforces the distinction between scalars and length-one arrays). Also labelpr to print just a label.
R_withCallingErrorHandler is now available for establishing a calling handler in C code for conditions inheriting from class error.

INSTALLATION on a UNIX-ALIKE

User-set ‘⁠DEFS⁠’ (e.g., in ‘config.site’) is now used for compiling packages (including base packages).
There is a new variant option --enable-lto=check for checking consistency of BLAS/LAPACK/LINPACK calls — see ‘Writing R Extensions’.
A C++ compiler default is set only if the C++11 standard is supported: it no longer falls back to C++98.
PCRE2 is used if available. To make use of PCRE1 if PCRE2 is unavailable, configure with option --with-pcre1.
The minimum required version of libcurl is now 7.28.0 (Oct 2012).
New make target distcheck checks
- R can be rebuilt from the tarball created by make dist,
- the build from the tarball passes make check-all,
- the build installs and uninstalls,
- the source files are properly cleaned by make distclean.

UTILITIES

R --help now mentions the option --no-echo (renamed from --slave) and its previously undocumented short form -s.
R CMD check now optionally checks configure and cleanup scripts for non-Bourne-shell code (‘bashisms’).
R CMD check --as-cran now runs ⁠\donttest⁠ examples (which are run by example()) instead of instructing the tester to do so. This can be temporarily circumvented during development by setting environment variable _R_CHECK_DONTTEST_EXAMPLES_ to a false value.

PACKAGE INSTALLATION

There is the beginnings of support for the recently approved C++20 standard, specified analogously to C++14 and C++17. There is currently only limited support for this in compilers, with flags such as -std=c++20 and -std=c++2a. For the time being the configure test is of accepting one of these flags and compiling C++17 code.

BUG FIXES

formula(x) with length(x) > 1 character vectors, is deprecated now. Such use has been rare, and has ‘worked’ as expected in some cases only. In other cases, wrong x have silently been truncated, not detecting previous errors.
Long-standing issue where the X11 device could lose events shortly after startup has been addressed (PR#16702).
The data.frame method for rbind() no longer drops <NA> levels from factor columns by default (PR#17562).
available.packages() and hence install.packages() now pass their ... argument to download.file(), fulfilling the wish of PR#17532; subsequently, available.packages() gets new argument quiet, solving PR#17573.
stopifnot() gets new argument exprObject to allow an R object of class expression (or other ‘language’) to work more consistently, thanks to suggestions by Suharto Anggono.
conformMethod() now works correctly in cases containing a “&& logic” bug, reported by Henrik Bengtsson. It now creates methods with "missing" entries in the signature. Consequently, rematchDefinition() is amended to use appropriate .local() calls with named arguments where needed.
format.default(*, scientific = FALSE) now corresponds to a practically most extreme options(scipen = n) setting rather than arbitrary n = 100.
format(as.symbol("foo")) now works (returning "foo").
postscript(.., title = *) now signals an error when the title string contains a character which would produce corrupt PostScript, thanks to PR#17607 by Daisuko Ogawa.
Certain Ops (notably comparison such as ==) now also work for 0-length data frames, after reports by Hilmar Berger.
methods(class = class(glm(..))) now warns more usefully and only once.
write.dcf() no longer mangles field names (PR#17589).
Primitive replacement functions no longer mutate a referenced first argument when used outside of a complex assignment context.
A better error message for contour(*, levels = Inf).
The return value of contourLines() is no longer invisible().
The Fortran code for calculating the coefficients component in lm.influence() was very inefficient. It has (for now) been replaced with much faster R code (PR#17624).
cm.colors(n) etc no longer append the code for alpha = 1, "FF", to all colors. Hence all eight *.colors() functions and rainbow() behave consistently and have the same non-explicit default (PR#17659).
dnorm had a problematic corner case with sd == -Inf or negative sd which was not flagged as an error in all cases. Thanks to Stephen D. Weigand for reporting and Wang Jiefei for analyzing this; similar change has been made in dlnorm().
The optional iter.smooth argument of plot.lm(), (the plot() method for lm and glm fits) now defaults to 0 for all glm fits. Especially for binary observations with high or low fitted probabilities, this effectively deleted all observations of 1 or 0. Also, the type of residuals used in the glm case has been switched to "pearson" since deviance residuals do not in general have approximately zero mean.
In plot.lm, Cook's distance was computed from unweighted residuals, leading to inconsistencies. Replaced with usual weighted version. (PR#16056)
Time-series ts(*, start, end, frequency) with fractional frequency are supported more consistently; thanks to a report from Johann Kleinbub and analysis and patch by Duncan Murdoch in PR#17669.
In case of errors mcmapply() now preserves attributes of returned "try-error" objects and avoids simplification, overriding SIMPLIFY to FALSE. (PR#17653)
as.difftime() gets new optional tz = "UTC" argument which should fix behaviour during daylight-savings-changeover days, fixing PR#16764, thanks to proposals and analysis by Johannes Ranke and Kirill Müller.
round() does a better job of rounding “to nearest” by measuring and “to even”; thanks to a careful algorithm originally prompted by the report from Adam Wheeler and then others, in PR#17668.
round(x, dig) for negative digits is much more rational now, notably for large |dig|.
Inheritance information on S4 classes is maintained more consistently, particularly in the case of class unions (in part due to PR#17596 and a report from Ezra Tucker).
is() behaves more robustly when its argument class2 is a classRepresentation object.
The warning message when attempting to export an nonexistent class is now more readable; thanks to Thierry Onkelinx for recognizing the problem.
choose() misbehaved in corner cases where it switched n - k for k and n was only nearly integer (report from Erik Scott Wright).
mle() in the stats4 package had problems combining use of box constraints and fixed starting values (in particular, confidence intervals were affected).
Operator ? now has lower precedence than = to work as documented, so = behaves like <- in help expressions (PR#16710).
smoothEnds(x) now returns integer type in both cases when x is integer, thanks to a report and proposal by Bill Dunlap PR#17693.
The methods package does a better job of tracking inheritance relationships across packages.
norm(diag(c(1, NA)), "2") now works.
subset() had problems with 0-col dataframes (reported by Bill Dunlap, PR#17721).
Several cases of integer overflow detected by the ‘undefined behaviour sanitizer’ of clang 10 have been circumvented. One in rhyper() may change the generated value for large input values.
dotchart() now places the y-axis label (ylab) much better, not overplotting labels, thanks to a report and suggestion by Alexey Shipunov.
A rare C-level array overflow in chull() has been worked around.
Some invalid specifications of the day-of-the-year (via %j, e.g. day 366 in 2017) or week plus day-of-the-week are now detected by strptime(). They now return NA but give a warning as they may have given random results or corrupted memory in earlier versions of R.
socketConnection(server = FALSE) now respects the connection timeout also on Linux.
socketConnection(server = FALSE) no longer leaks a connection that is available right away without waiting (e.g. on ‘⁠localhost⁠’).
Socket connections are now robust against spurious readability and spurious availability of an incoming connection.
blocking = FALSE is now respected also on the server side of a socket connection, allowing non-blocking read operations.
anova.glm() and anova.glmlist() computed incorrect score (Rao) tests in no-intercept cases. (André Gillibert, PR#17735)
summaryRprof() now should work correctly for the Rprof(*, memory.profiling=TRUE) case with small chunk size (and "tseries" or similar) thanks to a patch proposal by Benjamin Tyner, in PR#15886.
xgettext() ignores strings passed to ngettext(), since the latter is handled by xngettext(). Thanks to Daniele Medri for the report and all the recent work he has done on the Italian translations.
data(package = "P") for P in base and stats no longer reports the data sets from package datasets (which it did for back compatibility for 16 years), fixing PR#17730.
x[[Inf]] (returning NULL) no longer leads to undefined behavior, thanks to a report by Kirill Müller in PR#17756. Further, x[[-Inf]] and x[[-n]] now give more helpful error messages.
Gamma() family sometimes had trouble storing link name PR#15891

BUG FIXES (Windows)

Sys.glob() now supports all characters from the Unicode Basic Multilingual Plane, no longer corrupting some (less commonly used) characters (PR#17638).
Rterm now correctly displays multi-byte-coded characters representable in the current native encoding (at least on Windows 10 they were sometimes omitted, PR#17632).
scan() issues with UTF-8 data when running in a DBCS locale have been resolved (PR#16520, PR#16584).
Rterm now accepts enhanced/arrow keys also with ConPTY.
R can now be started via the launcher icon in a user documents directory whose path is not representable in the system encoding.
socketConnection(server = FALSE) now returns instantly also on Windows when connection failure is signalled.
Problems with UTF-16 surrogate pairs have been fixed in several functions, including tolower() and toupper() (PR#17645).

CHANGES in previous versions

Older news can be found in text format in files NEWS.0, NEWS.1, NEWS.2 and NEWS.3 in the ‘doc’ directory. News in HTML format for R versions 3.x and from 2.10.0 to 2.15.3 are available at NEWS.3.html and NEWS.2.html.