• Long stringed error messages are now protected from premature garbage collection, fixing PR#19210, reported and analyzed by Yuancheng Jiang.

• ‘ksmooth(x,y, x.points=NULL)’ now returns an empty (x,y) pair instead of crashing R, fixing PR#19153.

  Additionally, also by Adam Berkeš, ‘x <- rep(999,0); ksmooth(x, x, x.points = 1)’ no longer writes out of bounds, fixing PR#19171. Ditto for ‘ksmooth(x, x, n.points = 0)’, PR#19219.

Changes in R 4.6.1 Bug Fixes

• ‘wilcox.test(x, exact=FALSE, correct = k)’'s p-value computation got a missing ‘dnorm(z)’ factor, and so did the 2-sample case, in addition to more fixes.

  Further, if ‘wilcox.test(.., exact=TRUE)’'s p-value is close to the 0 or 1 boundaries, the calculation no longer suffers severely from cancellation, thanks to Tasuku Kobayashi's reports and Ahmed Sattar Jabbar's suggestion in PR#19144.

• ‘predict(smooth.spline(..), deriv = -99)’ and similar invalid ‘deriv’ values now signal errors instead of segfaulting, thanks to Adam Berkeš' report and proposal in PR#19190.

• ‘format(x, width = 2^31 -1)’ for an non-ascii character ‘x’ such as ‘x = "\u00e9"’ now signals an error as the required width is too large, rather than segfaulting, thanks to Adam Berkeš' report in PR#19188.

• ‘besselI(1, 1e11)’ and ‘besselK(..)’ now signal a warning and return ‘NaN’ instead of typically segfaulting, fixing PR#19175 thanks to Ben Bolker.

  Further, ‘besselK(1, -1e11)’ and similar warn about too large ‘|nu|’, returning ‘NaN’ rather than segfaulting, fixing PR#19196 thanks to Adam Berkeš.

• ‘influence.measures()’ inadvertently wasn't updated along with ‘dffits()’, ‘dfbetas()’, ‘covratio()’. PR#19167 by Amal Tawfik.

• ‘besselI(1, 1e11)’ and ‘besselK(..)’ now signal a warning and return ‘NaN’ instead of typically segfaulting, fixing PR#19175 thanks to Ben Bolker.

• ‘text.default(.., col = numeric(0))’ and similar no longer segfault in "instrumented" versions of R, fixing PR#19178 thanks to Jiang Yuancheng's ‘fusion-fuzz’ and Ivan Krylov.

• ‘R CMD rtags’ (on Unix-alikes) no longer fails from a bad escape if ‘sh’ is ‘bash’ or ‘busybox’.

• ‘capabilities("X11")’ no longer incorrectly returns ‘TRUE’ on a Unix-alike where X11 is not actually available when built by a C compiler without C23 ‘enum’ base types, thanks to Trevor Davis' report and patch in PR#19180.

Changes in R 4.6.1 patched Bug Fixes (Windows)

• ‘file.copy(*, date=TRUE)’ no longer opens files for exclusive access when copying the file time. Consequently, the time _is_ copied now and concurrent attempts to open the source file should work reliably, thanks to Kevin Ushey's report and patch in PR#19187.

• ‘path.expand("~")’ and similar now should work correctly on Windows when the user name is not in ASCII and neither ‘%HOME%’ nor ‘%USER%’ environment variables are set, fixing PR#18949 thanks to the report and patch from Ivan Krylov and Mauricio Vargas's R Dev Day work.

Changes in R 4.6.1 patched Bug Fixes

• ‘strptime("0", "%w")’ in a ‘"C"’ locale now works in valid cases, returning ‘NA’ for invalid week numbers (‘"%U"’ or ‘"%W"’), fixing PR#19124 thanks to Michael Chirico's report and notably Suharto Anggono's analysis, also correctly fixing PR#15195.

• ‘ksmooth(x,y, x.points=NULL)’ now returns an empty (x,y) pair instead of crashing R, fixing PR#19153.

  Additionally, also by Adam Berkeš, ‘x <- rep(999,0); ksmooth(x, x, x.points = 1)’ no longer writes out of bounds, fixing PR#19171.

• ‘strptime(ch, "...%OS<n>...")’ now disregards contiguous digits in "<n>", for symmetry with ‘strftime()’, fulfilling Frederick Eaton's wish in PR#17209, thanks to a patch by Suharto Anggono.

• ‘strptime("0", "%w")’ in a ‘"C"’ locale now works in valid cases, fixing PR#19124 thanks to Michael Chirico.

• ‘strptime()’ now also returns ‘NA’ for out of range ‘"%OS"’ and a correct error message in some wrong multibyte cases, fixing PR#19117 comment #1 and PR#19122 by Michael Chirico; additionally, some overflow to ‘Inf’ times no longer result in ‘NA’.

• ‘ksmooth(x,y, x.points=NULL)’ now returns an empty (x,y) pair instead of crashing R, fixing PR#19153.

Changes in R 4.5.0 Deprecated and Defunct

• 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’, ‘insertMethod’, ‘makeMethodsList’, ‘mergeMethods’, ‘MethodsList’, ‘MethodsListSelect’, and ‘SignatureMethod’ were made defunct, as were the ‘"MethodsList"’ branches of functions ‘assignMethodsMetaData’, ‘finalDefaultMethod’, and ‘MethodAddCoerce’.

• Quartz device now correctly draws long paths (work-around for Quartz built-in stroker breaking long paths). Thanks to R Dev Day @ useR! 2026 contributors, notably Tomek Gieorgijewski, report in PR#18680.

• ‘<matrix>[[i, j]]’ with negative ‘i’ occasionally gives no error but accesses ‘previous content’; thanks to Kevin Ushey's report and very simple fix in PR#19116.

• Now ‘PROTECT()’ in ‘SubassignTypeFix’, fixing PR#19110 thanks to Kevin Ushey.

• ‘writeChar()’ in a multibyte locale counts characters and bytes consistently and no longer overflows, thanks to Kevin Ushey's report and patch in PR#19112.

• ‘dim(a) <- vec’ now checks for too large ‘prod(vec)’, thanks to Kevin Ushey's report and patch in PR#19109.

• Tweaks (including to the parsers) for the C23 behaviour (preserving ‘const’) of ‘strchr’, ‘strrchr’ and ‘strstr’. (By Brian Ripley and Duncan Murdoch.)

• ‘make check-devel’ now works without recommended packages.

• Wrapper objects make sure data pointers remain once obtained remain valid as long as a wrapper object is reachable. Reported by Ivan Krylov.

• Wrappers now duplicate even a wrapped object that might be shared before returning a read-only pointer. This prevents cached read-only pointers from becoming invalid. Reported by Ivan Krylov.

• Wrappers now duplicate even a wrapped object that might be shared before returning a read-only pointer. This prevents cached read-only pointers from becoming invalid. Reported by Ivan Krylov.

• Wrapper objects make sure data pointers remain once obtained remain valid as long as a wrapper object is reachable. Reported by Ivan Krylov.

• ‘dummy.coef()’ becomes more robust to non-syntactic variable names, fixing PR#18468. Thanks to Bill Dunlap and ‘R Dev Day’ participants Vincent Arel-Bundock, Cynthia Huang, Tina Rozsos and Marina Marinelli.

• ‘rhyper(N, m, n, k)’ now switches to the “large” scenario when ‘m + n’ is larger than ‘.Machine$integer.max’, preventing integer overflow, thanks to Jonathan Blood's report on R-devel.

• Fix long standing (Fortran compiler optimization related) bug in ‘nlminb’ with constraints, thanks to Kasper Kristensen's PR#19086 report and patch.

• Wrappers now duplicate even a wrapped object that might be shared before returning a read-only pointer. This prevents cached read-only pointers from becoming invalid. Reported by Ivan Krylov.

• Fix for PR#19100: ‘seq.int’ was not handling non-vector ‘along.width’ arguments properly. Thanks to Mitchell O'Hara-Wild.

• In plain-text help (‘Rd2txt’), paragraphs are again recognized even when started with a non-indented Rd comment, fixing a regression in R 4.4.0.

• In ‘methods’, ‘as()’ now correctly coerces S4 objects to S4 superclasses extending old-style classes, instead of returning only the S3 part.

• Overly long ‘dyn.load()’ error messages (C level ‘dlerror()’), should no longer corrupt its state, thanks to Ivan Krylov's PR#19029 report and patch.

• ‘as.matrix(<POSIXlt>)’ again produces a _numeric_ matrix, and the ‘c()’ and subassignment methods for ‘POSIXlt’ objects work correctly more often, e.g., without a ‘"tzone"’ attribute, back porting a few of the PR#18989 fixes from R-devel, both thanks to Suharto Anggono.

• The border case ‘zapsmall(x, digits=Inf)’ where ‘x’ contains an ‘Inf’ entry no longer returns all ‘NaN’ but rather ‘x’. The improved help page now has more non-default examples.

• The data part of ‘getGenerics()’ listed package names for generic functions defined in more than one package. Now it lists generic function names, as intended. Thanks to Michael Chirico for report and patch proposal (PR#19080).

Changes in R 4.6.0 Bug Fixes

• The ‘Pair(x,y)’ construction in the formula interface to paired tests did not work with the ‘subset’ argument, due to the absence of a ‘[.Pair’ method, which has now been added (PR#18898).

• When ‘browser()’ is active or when otherwise debugging, R code such as ‘if(TRUE)’ no longer triggers a new browser level, fixing PR#18885 (differently than the fix for PR#15770), with thanks to Ivan Krylov.

• The LaTeX class ‘jss’ bundled in ‘share/texmf/tex/latex/jss.cls’ has been updated to work with ‘hyperref’ version 7.01q (2026/04/24).

• Plain-text (and legacy HTML) conversion for a simple Rd \eqn{} now handles \geq, \leq, \neq and \ne in addition to \ge and \le (PR#19070).

Changes in R 4.6.1 Bug Fixes

• ‘abbreviate(<non-ASCII>)’ now works better, using ‘iswlower()’ and ‘*upper()’ to treat “wide” characters, thanks to Kevin's PR#19058.

• ‘cut(1:11, {})’ now signals an error for the invalid ‘breaks’, fixing PR#19057, thanks to Kevin Ushey.

• ‘all(<symbol>)’ signals an error now, as some similar coercions; previously, the coercion of the symbol resulted in ‘NULL’ internally, raised a warning, and could access illegal memory; thanks to Kevin Ushey's PR#19054.

• ‘stl()’ now checks its 3 x 3 tuning parameters on the R level; ‘stl(*, s.window = 0)’ now “works” instead dumping core, ‘stl(*, s.window = 1)’ “works” correctly, too. Also, the ‘summary()’ method mentions the robustness ‘weights’ only if any robustness iterations happened.

  Further, ‘stl()’ is now based on C code, translated from previous Fortran, triggered by a flang 22 compiler optimization bug (‘-O2’).

• Border case ‘zapsmall(x, digits=Inf)’ where ‘x’ has an ‘Inf’ entry, no longer returns all ‘NaN’ but rather ‘x’. Help page improved, also with more non-default examples.

• ‘wilcox.test(x, exact=FALSE, correct = k)’'s p-value computation got a missing ‘dnorm(z)’ factor, and so did the 2-sample case, in addition to more fixes.

• Data part of ‘getGenerics()’ listed package names for generic functions defined in more than one package. Now it lists generic function names, as intended. Thanks to Michael Chirico for report and patch proposal (PR#19080).

• Data part of ‘getGenerics()’ listed package names for generic functions defined in more than one package. Now it lists generic function names, as intended. Thanks to Michael Chirico for report and patch proposal (PR#19080).

• ‘wilcox.test(x, exact=FALSE, correct = k)’'s p-value computation got a missing ‘dnorm(z)’ factor, and so did the 2-sample case, in addition to more fixes.

• Border case ‘zapsmall(x, digits=Inf)’ where ‘x’ has an ‘Inf’ entry, no longer returns all ‘NaN’ but rather ‘x’. Help page improved, also with more non-default examples.

• ‘stl()’ now checks its 3 x 3 tuning parameters on the R level; ‘stl(*, s.window = 0)’ now “works” instead dumping core, ‘stl(*, s.window = 1)’ “works” correctly, too. Also, the ‘summary()’ method mentions the robustness ‘weights’ only if any robustness iterations happened.

  Further, ‘stl()’ is now based on C code, translated from previous Fortran, triggered by a flang 22 compiler optimization bug (‘-O2’).

• ‘abbreviate(<non-ASCII>)’ now works better, using ‘iswlower()’ and ‘*upper()’ to treat “wide” characters, thanks to Kevin's PR#19058.

• ‘all(<symbol>)’ signals an error now, as some similar coercions; previously, the coercion of the symbol resulted in ‘NULL’ internally, raised a warning, and could access illegal memory; thanks to Kevin Ushey's PR#19054.

• Plain-text (and legacy HTML) conversion for a simple Rd \eqn{} now handles \geq, \leq, \neq and \ne in addition to \ge and \le (PR#19070).

• ‘cut(1:11, {})’ now signals an error for the invalid ‘breaks’, fixing PR#19057, thanks to Kevin Ushey.

• The LaTeX class ‘jss’ bundled in ‘share/texmf/tex/latex/jss.cls’ has been updated to work with ‘hyperref’ version 7.01q (2026/04/24).

Changes in R 4.6.0 Bug Fixes

• The ‘"tzone"’ attribute of ‘"POSIXlt"’ objects should no longer depend on earlier calls, fixing PR#19005 thanks to Ivan Krylov, a patch by Suharto Anggono and reports of “Non-deterministic POSIXlt tzone in Europe/London ..” on R-devel.

• When subassigning ‘"POSIXlt"’, e.g., ‘<dat>[i] <- v’, ‘v’ is now converted to the time zone of ‘dat’, before being assigned, see PR#18919.

Changes in R 4.5.2 Bug Fixes

• Subassigning ‘"POSIXlt"’, i.e., ‘<tdat>[i] <- val’ and ‘<tdat>[[i]] <- val’ now rebalance as they should; thanks mostly to Mikael Jagan's PR#18919.

• When ‘file.choose()’ is terminated with an ‘EOF’, it now signals an error rather than returning garbage, thanks to Kevin Ushey's report and patch in PR#19053,

• ‘intToUtf8(<negative>)’ now returns ‘NA’ and no longer accesses invalid memory, thanks to Kevin Ushey's report with patch in PR#19052.

Changes in R 4.5.2 Bug Fixes

• Subassigning ‘"POSIXlt"’, i.e., ‘<tdat>[i] <- val’ and ‘<tdat>[[i]] <- val’ now rebalance as they should; additionally, ‘val’ is now converted to the time zone of ‘tdat’; thanks mostly to Mikael Jagan's PR#18919.

• The Sweave driver ‘Rtangle’ no longer puts empty lines at the end of tangled scripts.

Changes in R 4.6.0 New Features

• The Sweave driver ‘RweaveLatex’ now allows the value of logical and numerical chunk options (only) to be the name of an object defined in earlier, evaluated code chunks. This is useful to pass computed values to options. For options set this way for weaving purposes, the ‘Rtangle’ driver rather uses their default values, with a warning. By Vincent Goulet.

• The Sweave driver ‘RweaveLatex’ gains an option to include unparsable R code or arbitrary text in code chunks. Chunks marked as ‘ignore.on.weave = TRUE’ are completely ignored on weaving, i.e., not even parsed. The chunks however remain written out verbatim on tangling.

  Similarly, the driver ‘Rtangle’ gains an option to control the extraction of code chunks. Chunks marked as ‘ignore.on.tangle=TRUE’ are processed as usual on weaving, but left out of the tangled scripts (or thrown away when ‘split=TRUE’).

  The drivers also support the shorter aliases ‘weave’ for ‘!ignore.on.weave’, and ‘tangle’ for ‘!ignore.on.tangle’. A further option ‘ignore’, available for both drivers, sets ‘ignore.on.weave’ and ‘ignore.on.tangle’ at once.

  By Vincent Goulet.

• The Sweave driver ‘Rtangle’ now provides an option ‘chunk.sep’ to control the separator between code chunks in tangled scripts (with an unchanged default of ‘\n\n’). Using ‘check.sep=FALSE’ omits the separator (between two chunks when used as a chunk option). By Vincent Goulet.

• The Sweave driver ‘Rtangle’ now provides an option ‘extension’ to specify the extension, without the leading dot, for the file name of a tangled code chunk when splitting is selected (the option has no effect with ‘split=FALSE’). If ‘TRUE’, the default extension of ‘Rtangle’ (usually ‘.R’) is used; if ‘FALSE’, no extension is added to the file name. By Vincent Goulet.

• New function ‘SweaveGetSourceName’ in package ‘utils’ to obtain the name of the file being woven by an ‘Sweave’ process launched from the command line. By Vincent Goulet.

• When ‘Ops’ group methods for matrix-‘"ts"’ return a zero-extent matrix, its type is correct now. E.g., ‘<int> + <dbl>’ now returns type ‘"double"’, see also PR#18972.

• The ‘"Built"’ column returned by ‘installed.packages()’ and ‘old.packages()’ now contains the full value of the ‘"Built"’ entry from the (installed) ‘DESCRIPTION’ file. Previously, only the R version from the ‘"Built"’ entry was returned.

• If the timestamp passed as ‘--built-timestamp’ to ‘R CMD INSTALL’ is in RFC-2822 form (with time-zone offset) it will be converted to ISO UTC form to conform to the format used by R for purposes described above. (PR#19037, thanks to Dirk Eddelbuettel)

• If R uses custom binary type in its ‘.Platform$pkgType’ then ‘R CMD INSTALL --build’ will produce ‘<package>_<ver>_R_<system>-<build>.tar.xz’ binary files. Please note that future versions may use ‘.zstd’ compression by default so package tooling should support any of the above mentioned extensions.

Changes in R 4.6.0 Package Installation

• The ‘"Built"’ column returned by ‘available.packages()’ and ‘old.packages()’ now contains the full value of the ‘"Built"’ entry (if present) in the ‘DESCRIPTION’ file. Previously, only the R version from the ‘"Built"’ entry was returned.

• If the timestamp passed as -built-timestamp to ‘R CMD INSTALL’ is in RFC-822 form (with time-zone offset) it will be converted to ISO UTC form to conform to the format used by R for purposes described above. (PR#19037, thanks to Dirk Eddelbuettel)

• The internal ‘cwilcox’ function used in computations for the Wilcoxon distribution is now based on an implementation of a formula by Andreas Löffler provided by Andreas Löffler, Aidan Lakshman, and Ivan Krylov, substantially reducing the memory complexity of the original implementation (PR#18655).

• New function ‘messageCondition()’ to create structured ‘"message"’ objects analogous to ‘warningCondition()’ and ‘errorCondition()’ (PR#18940, by Trevor Davis).

• ‘hatvalues()’ now has a method for ‘nls’ (nonlinear model) results, prompted by the proposal of Patrice Kiener and Heather Turner in PR#18897.

• New function ‘R_getRegisteredNamespace’ finds and returns the namespace environment registered for a name, or ‘R_NilValue’ if none is found.

• Parsing deeply nested expressions no longer should segfault in certain circumstances, fixing five different checks on context stack size, thanks to Kevin Ushey's report and Michael Chirico's patch in PR#18994.

• The R citation now provides a DOI (10.32614/R.manuals): please update your bibliographies accordingly.

• The default C++ standard has been changed to C++20 where available (which it is on all known platforms from 2021 on): if not C++17 is used if available otherwise C++ is not supported (as before).

  (GCC 16 has also switched to C++20 as its default.)

  Packages can request C++17 if essential.

Changes in R 4.6.0 New Features

• The default ‘AIC’ and ‘BIC’ methods now check whether the ‘methods’ namespace is loaded rather than ‘stats4’. They still use ‘stats4::logLik’ (and ‘stats4::nobs’), but packages no longer need to load ‘stats4’ explicitly.

• ‘confint.default()’ now also works on S4 objects, as long as suitable ‘coef()’ and ‘vcov()’ methods exist.

• ‘binomial(identity)’ and ‘quasibinomial(identity)’ now work without having to quote the argument.

• ‘str()’ now shows more via ‘format()’ for external pointers.

• ‘terms(<formula>, specials = *)’ now treats non-syntactic specials more gracefully, thanks to Mikael Jagan's PR#18568.

• ‘help.start()’ gets a ‘lib.loc’ option and its default for ‘make.packages.html()’ is enhanced to allow, e.g., fast access to ‘.Library’ when that contains only base and recommended packages.

• In ‘*.Rd’ help files, the \linkS4class macro now also works for links to other packages via \linkS4class[<pkg>]{<myClass>}, much nicer than the “workaround” \link[<pkg>:<myClass>-class]{<myClass>} necessary in earlier versions of R.

  Packages with the new syntax need to formally depend on ‘R >= 4.6.0’.

• ‘tools::analyze_license()’ now also computes SPDX license identifiers, thanks to Thierry Onkelinx and LLuís Revilla.

• ‘read.dcf()’ now recognizes lines starting with ‘#’ as comment lines. By Dirk Eddelbuettel, Laurent Gatto and Hugo Gruson.

• ‘tcltk::tclVersion()’ now only optionally includes the ‘patch level’, as Tcl full versions can be of the form ‘8.7a5’ or ‘9.0b1’ without three clear components.

• ‘untar(tar = "internal")’ supports ‘extras = "-P"’ to use unchanged the recorded file paths (as many external ‘tar’ programs do).

• ‘extSoftVersion()[["zstd"]]’ now reports the version of the ‘zstd’ compression library if available, thanks to Trevor Davis' patch proposal in PR#18914.

• New logical ‘option()’ ‘quiet’, defaulting to false, set to ‘TRUE’ by R's command-line option ‘--quiet’ (and similar), now can be switched during an R session. Prompted by Dirk Eddelbuettel's proposal in PR#18913.

• Credentials for basic HTTP authentication with download method ‘"libcurl"’ can now be provided in a ‘netrc’ file. The path to the file can be specified in ‘options("netrc")’.

• ‘tools::deparseLatex()’ gains a ‘math’ argument, now used by the default ‘bibstyle’ to format ‘bibentry()’ fields with ‘$...$’ syntax via Rd \eqn markup.

• ‘gzcon()’ can now decompress a concatenation of compressed streams PR#18887.

• Bibliographic citations and references in Rd files can now be auto-generated from bibentries in bibliographic databases in R or BibTeX formats. See ‘RShowDoc("R-exts#Bibliographic-citations-and-references")’ for more information.

• Arguments to ‘loadNamespace()’ which will be ignored because the namespace is already loaded are now noted.

• ‘chkDots()’' optional argument ‘allowed’ has been implemented thanks to Trevor Davis' proposal in PR#18936.

• ‘wilcox.test()’ can now perform exact (conditional) inference in case of ties. Based on contributions by Torsten Hothorn.

• ‘wilcox.test()’ can now optionally compute improved asymptotic p-values by including up to 3 correction terms of the Edgeworth series for the normal approximation.

• ‘barplot(.., orderH = *)’ for stacked bar plots allows to sort the stacks each according to size.

• New argument ‘panel.first’ for ‘hist()’ (via ‘plot.histogram()’), ‘barplot()’, ‘bxp()’, and hence implicitly ‘boxplot()’. All except the former also gain a new ‘panel.last’. Suggested by Marieke Stolte and Julian Welz.

• ‘plot.default()’ gets a new switch ‘lim2’ to indicate that the default ‘xlim’ and ‘ylim’ range computations only use _jointly_ finite x- and y-values; indirectly suggested in PR#7986 by Jincai Jiang.

• ‘Rman.css’, the stylesheet for the ‘texi2any’-generated HTML versions of the R manuals, was improved following joint efforts at the ‘R Dev Days’ of useR! 2024 and RSECon25.

• New system Rd macro ‘\manual{<name>}{<node>}’ to refer to a specific section _etc_ (possibly empty, for ‘Top’) of one of the R manuals (e.g., ‘R-exts’).

• ‘list.files()’ now has optional argument ‘fixed’ to allow literal pattern matching. Suggested and implemented by Duncan Murdoch in PR#18925.

• ‘substring(txt, i1, i2)’, ‘substr(..)’ and their replacement versions now accept ‘i2 = NULL’ to mean “to the end_of_string”, thus fulfilling Kevin Ushey (and others') suggestions in PR#18851.

• The default method for ‘pretty()’ gets a new switch ‘bounds’ for completeness, corresponding to ‘.pretty()’. Also, it now catches typos such as ‘eps.corrected = 2’, noted in PR#18521 by Mikko Korpela.

• Plain-text help now renders Rd \describe lists using line breaks after item labels. Set ‘tools::Rd2txt_options(descStyle=NULL)’ to get the old behaviour with a simple space; a ‘"colon"’ variant is also available.

• ‘x %notin% table’ newly in ‘base’ is an idiom for ‘!(x %in% table)’ and provided almost entirely for convenience and code readability, from an R-devel suggestion, after many years of private definitions mostly hidden in packages, including in R's ‘tools’ package.

• The default method of ‘sequence()’ gets a new option ‘recycle’ to swap between current (not fully recycling) and future behaviour where all three of ‘(nvec, from, by)’ are jointly recycled.

• ‘ftable()’s default method and the ‘as.table()’ method for ‘"ftable"’s get a ‘perm’ argument with back compatible default. The ‘as.table()’ method also gets a ‘named.dim = FALSE’ switch, no longer creating a named ‘dim(<result>)’ by default.

• ‘match.arg()’ gets a new option ‘several.ok = "all"’, fulfilling the wish of Jim Hester in PR#16659.

• ‘provideDimnames()’ gets new switch ‘use.names’, as proposed including patch by Mikael Jagan, in PR#18975.

• The default ‘summary()’ is more informative for character vectors, optionally resorting to the factor method via the new argument ‘character.method = "factor"’, e.g., when summarizing a data frame (PR#16750).

  It also provides more useful summaries for complex vectors, with ‘polar’ determining if polar or cartesian coordinates are more relevant; mostly based on a proposal by Mikael Jagan.

• Error messages from failed Rd \Sexpr code now include the call from the original condition (if available). Warning messages now include Rd source locations.

• When the environment variable ‘R_WARN_BOUNDS_OPT’ is set to ‘"yes"’, ‘options(warn = val)’ will check if ‘val’ is inside ‘-1:2’; this may happen unconditionally in the future.

• ‘weighted.residuals()’ now returns weighted working residuals for ‘"glm"’ objects. It used to return deviance residuals, but these do not give the one-step approximated ‘dfbeta’ values, as pointed out by Ravi Varadhan. ‘influence.glm()’ has been amended so that it now returns an object with both a ‘"wt.res"’ and a ‘"dev.res"’ element.

• Several influence measures for ‘"glm"’ objects have been updated to use Pearson residuals rather than deviance residuals (the latter are not unbiased) and to not use leave-one-out estimates of dispersion in models with fixed dispersion. Thanks to Ravi Varadhan for discussions and testing of these updates.

• R now supports custom binary types which are of the form ‘"<system>.binary.<build>"’ where ‘<system>’ is lower-case name (letters only) of the system and ‘<build>’ is the name of the build (alphanumeric and dashes). The corresponding paths returned by ‘contrib.url’ (which govern the repository layout) with the above ‘type=’ have the form ‘bin/<system>/<build>/contrib/<x.y>’ where ‘<x.y>’ is the R version without patch level. This is a generalisation of the binary types previously supported on macOS. In addition, binary packages can have the extensions ‘.tar.bz2’, ‘.tar.xz’, ‘.tar.zst’ and ‘.tar.zstd’ with the corresponding compression support.

• The value of ‘.Platform$pkgType’ which defines the native binary type for the current build of R can be overridden with ‘R_PLATFORM_PKGTYPE’ environment variable (previously this was only set by the macOS builds of R). This should be typically only done by the author of a binary R distribution to define the type of binaries supported by that build of R.

• If R uses custom binary type in its ‘.Platform$pkgType’ then ‘R CMD INSTALL --build’ will produce ‘<package>_<ver>_R_<system>-<build>.tar.zstd’ binary files if R has ‘zstd’ support, ‘.tar.xz’ otherwise.

• New facilities have been introduced for package integrity verification and package signing. The optional file ‘SHA256’ in a package contains SHA-256 hashes, lengths and paths of files provided in the package allowing for more reliable integrity verification (relative to ‘MD5’). This file is now generated by default in ‘R CMD INSTALL --build’ and optionally via ‘R CMD build --sha256’. A package can be signed by creating a detached GnuPG signature file ‘SHA256.sig’ signing the entirety of the ‘SHA256’ file. Upon installation, the signature is verified using GnuPG, thus ensuring the integrity of the ‘SHA256’ file and by induction all files in the package. Both source and binary packages can be signed. Currently, this only applies to tar-based packages, and the command-line GnuPG ‘gpg’ tool (or equivalent tool named in the ‘GPG’ environment variable) has to be available for signing and verification to work. ‘R CMD INSTALL --sign’ can be used to sign binary packages, including its use with ‘--build’. System-wide GnuPG keyrings for the R installation can be placed in ‘<R_HOME>/etc/keyrings’ as files with ‘.gpg’ extensions and will be checked first before consulting user's GnuPG keyring (if present).

• Experimentally, several math library (‘math.h’) functions, such as ‘exp(.)’, ‘log1p()’, ‘sin()’, ‘atanh()’, when called from R, are now ensured to give fully accurate results in a small neighbourhood of special values, such as ‘exp(0) == 1’, ‘log1p(0) == 0’, etc. This makes R slightly less platform dependent for these functions, notably on platforms with less accurate system math libraries, see also <https://blog.r-project.org/2026/01/30/debugging-sensitivity-to-c-math-library-on-linux/>.

• Function ‘free1way()’ implementing semiparametrically efficient inference procedures (likelihood- and permutation-based) in distribution-free stratified K-sample one-way layouts was added to the ‘stats’ package. Approximate (via ‘power.free1way.test()’) and simulation-based (utilising ‘rfree1way()’ for random number generation) power-assessment and sample-size planning as well as model diagnostics (available from a ‘plot’ method and probability-probability plots in ‘ppplot()’) complement the functionality. Provided by Torsten Hothorn.

• ‘plot.data.frame()’ now supports a ‘formula’ argument.

• New Rd macro \linkS4methods{}, e.g., for easier linking to method docs in other packages, proposed and coded by Mikael Jagan in PR#18998.

• Class ‘"difftime"’ is now also among the S4 ‘"OldClasses"’.

• New function ‘bitstring()’ as a user-friendly wrapper around ‘intToBits()’, etc.

• ‘plot.lm()’ now omits the smoother in the residuals vs leverage plot. This never made much sense, but if you really want it, you can force the old behaviour by setting ‘panel.raw=panel.smooth’.

Changes in R 4.6.0 Graphics

• The graphics engine version, ‘R_GE_version’, has been bumped to ‘17’ and so packages that provide graphics devices should be reinstalled.

  The ‘glyphFont()’ function gains a ‘variations’ argument, which allows variable font axes to be specified, e.g., ‘c(wght = 100)’.

  Only the ‘quartz()’ device and Cairo-based graphics devices (but not ‘cairo_pdf()’) support variable font axes so far.

Changes in R 4.6.0 Installation on a Unix-Alike

• ‘configure’ appends ‘bsdtar’ to the list of command names it tries when finding a default for ‘TAR’.

• Failures in building the documentation for the base packages, including from parsing their Rd files, are no longer ignored by ‘make docs’.

• Building the R manuals now requires Texinfo 6.8 or later.

• A new ‘LIBR_LDFLAGS’ defaulting to ‘LDFLAGS’ allows more flexibility, e.g., for distributions such as Gentoo, Debian or Ubuntu, fixing PR#18992; additionally a ‘make’ failure to create ‘libR.pc’ should no longer be ignored, fixing PR#18993; both thanks to Benjamin Drung.

Changes in R 4.6.0 Checking an Installation

• There is a new directory ‘tests/C++Standards’ which contains small packages which can be test-installed to check support for various C++ standards. This is principally for use on Windows as on a Unix-alike this partially duplicates tests done by ‘configure’ - although it can also be used to test the behaviour of ‘R CMD INSTALL’ on unsupported standards.

Changes in R 4.6.0 Package Installation

• Specifying C++11 or C++14 in ‘src/Makevars’ has long given a note: in 99% of CRAN packages the specification was unnecessary as the default C++17 sufficed (in a few cases with a deprecation warning from some compilers).

  Support for these standards has been removed: the default C++ standard will be used.

  ‘R CMD config’ variables ‘CXX11’, ‘CXX14’ and their associated ‘CXXxxFLAGS’, ‘CXXxxPICFLAGS’ ‘CXXxxSTD’, ‘SHLIBCXXxxLD’ and ‘SHLIBCXXxxLDFLAGS’ variables are no longer supported and reported as ‘defunct’.

• When installing binary packages the time stamp in the ‘"Built"’ field is considered even if the package version is identical to allow binary package repositories to update binaries without the need to increase the package version.

Changes in R 4.6.0 C-Level Facilities

• New functions ‘GEcreateDD()’ and ‘GEfreeDD()’ for allocating (and initialising) ‘DevDesc’ structures. Can be used by external graphics devices. Satisfies PR#18292.

• New function ‘R_eval_with_gd()’ designed to “lock” a graphics device during call to ‘eval()’ within device drawing routines. External _on-screen_ graphics devices should consider using this function to avoid crashes from the device being closed by the user (e.g., a mouse click) during drawing.

• Declarations for non-API functions ‘LOGICAL0’, ‘INTEGER0’, ‘REAL0’, ‘COMPLEX0’, and ‘RAW0’ have been removed from installed header files.

• Non-API entry points ‘Rf_acopy_string’ and ‘Rf_lazy_duplicate’ have been added to those reported by ‘R CMD check’.

• Packages using the non-API functions ‘ATTRIB’ and ‘SET_ATTRIB’ will now receive check ‘NOTE’s. See ‘Writing R Extensions’ for alternatives to use.

• ‘R CMD check’ ‘NOTE’s on the use of these non-API entry points have been upgraded to ‘WARNING’s in preparation for removing declarations and, where possible, hiding these entry points: ‘R_nchar’, ‘R_tryWrap’, ‘Rf_GetOption’, ‘R_lsInternal’, ‘BODY’, ‘FORMALS’, ‘CLOENV’, ‘SET_TYPEOF’, ‘STRING_PTR’, ‘R_duplicate_attr’, ‘getConnection’, ‘R_data_class’, ‘STRING_PTR’, ‘SET_OBJECT’, ‘ATTRIB’, ‘SET_ATTRIB’, ‘Rf_findVarInFrame3’.

• The deprecated macros ‘CHARACTER_DATA’ and ‘CHARACTER_POINTER’ now return ‘const’ pointers since using writable pointers in packages is not safe.

• New function ‘DATAPTR_RW()’ for use in implementing ALTREP ‘Dataptr’ methods. This function should not be used in any other contexts.

• New function ‘R_class()’ as the ‘C’ equivalent of ‘class()’ in R.

• New function ‘Rf_isScalarString’.

• The ‘R_ObjectTable’ type definitions formerly in ‘R_ext/Callbacks.h’ are now available in the new header file ‘R_ext/ObjectTable.h’. This new header file should be used in packages instead of ‘R_ext/Callbacks.h’.

• Task callback support declared in ‘R_ext/Callbacks.h’ has been enabled again. It was disabled for R 4.5.0.

• The non-API header file ‘R_ext/PrtUtil.h’ is no longer copied to the installed ‘include’ directory.

• New function ‘R_mapAttrib’ for iterating over the attributes of an object.

• New functions ‘R_altrep_class_name’ and ‘R_altrep_class_package’ for retrieving the class name symbol and package name symbol of an ALTREP object. These should be used instead of ‘ALTREP_CLASS’.

• New function ‘R_getAttributes’ returns the same result as the R function ‘attributes’. New functions ‘R_getAttribCount’, ‘R_getAttribNames’, ‘R_hasAttrib’, ‘R_nrow’, and ‘R_ncol’.

• The function ‘Rf_isFrame’ has been removed; use ‘Rf_isDataFrame’ instead.

• The function ‘VECTOR_PTR’ has been removed.

  The non-API function ‘DATAPTR’ is no longer declared in an installed header file.

• These entry points are now marked as hidden and no longer have declarations in installed header files: ‘ENVFLAGS’, ‘EXTPTR_PROT’, ‘FRAME’, ‘ENCLOS’, ‘EXTPTR_PTR’, ‘EXTPTR_TAG’, ‘HASHTAB’, ‘IS_S4_OBJECT’, ‘LEVELS’, ‘NAMED’, ‘OBJECT’, ‘R_shallow_duplicate_attr’, ‘Rf_isValidString’, ‘Rf_lazy_duplicate’, ‘Rf_NonNullStringMatch’, ‘SETLENGTH’, ‘SETLEVELS’, ‘SET_BODY’, ‘SET_CLOENV’, ‘SET_ENCLOS’, ‘SET_FORMALS’, ‘SET_ENVFLAGS’, ‘SET_FRAME’, ‘SET_GROWABLE_BIT’, ‘SET_HASHTAB’, ‘SET_NAMED’, ‘SET_S4_OBJECT’, ‘SET_TRUELENGTH’, ‘STDVEC_DATAPTR’, ‘TRUELENGTH’, ‘UNSET_S4_OBJECT’, ‘XTRUELENGTH’.

• New experimental API for working with variable bindings in environments. The function ‘R_GetBindingType’ identifies the binding type without forcing a delayed or active binding. New bindings care created by ‘R_MakeDelayedBinding’, ‘R_MakeForcedBinding’ and ‘R_MakeMissingBinding’. Delayed and forced bindings can be inspected with ‘R_ForcedBindingExpression’, ‘R_DelayedBindingExpression’, and ‘R_DelayedBindingEnvironment’. Bindings for ‘...’ in function call environments can be examined with ‘R_findDotsEnv’, ‘R_DotsExist’, ‘R_DotsLength’, ‘R_DotsNames’, ‘R_DotsElt’, ‘R_GetDotType’, ‘R_DotDelayedExpression’, ‘R_DotDelayedEnvironment’, and ‘R_DotForcedExpression’. Contributed by Lionel Henry, Davis Vaughan, and Charlie Gao in PR#18928.

• New function ‘R_envSymbols’ returns a vector of the symbols for which an environment contains bindings (PR#18928).

• ‘R CMD check’ ‘NOTE’s on the use of the non-API entry points ‘PRCODE’, ‘SET_PRCODE’, ‘PRENV’, ‘SET_PRENV’, ‘PRVALUE’, ‘SET_PRVALUE’, ‘R_PromiseExpr’, and ‘Rf_allocSExp’ have been upgraded to ‘WARNING’s in preparation for removing declarations and, where possible, hiding these entry points.

• New functions ‘R_getVar’ and ‘R_getVarEx’. In most cases these can be used instead of the non-API functions ‘Rf_findVar’ and ‘Rf_findVarInFrame’. Other cases can be handled by the new API for working with variable bindings.

• Packages using any non-API variables will now receive check ‘NOTE’s.

Changes in R 4.6.0 Utilities

• ‘R CMD check’ now reports further ‘clang’ warnings including ‘-Wkeyword-macro’. This is most commonly seen for the C23 keywords ‘bool’, ‘true’ and ‘false’, but is also seen for ‘nullptr’ (C23 and C++11). Masking these by macros _may_ generate correct code (but not always) and always results in confusing-to-read code.

• The cascaded stylesheet ‘R.css’ now adds less vertical white space when rendering Rd files' \itemize, \enumerate, and \describe list \items to HTML.

  Where R is used via extensive IDEs such as ‘RStudio’, their maintainers may need to adapt ‘R.css’ files accordingly.

• ‘R CMD check’ when passed a tarball looks at its contents and so no longer derives the package name from the tarball name (which can now be arbitrary).

• Package ‘README.md’ files are now installed and featured in HTML help.

• ‘package.skeleton()’ now invisibly returns the path of the created directory, similar to ‘prompt()’ et al., and allows creating blank skeletons without any R objects.

Changes in R 4.6.0 Deprecated and Defunct

• ‘structure(NULL, <name> = <val>)’ is now defunct.

• Three ‘tk*.slaves()’ functions were deprecated in favor of ‘tk*.child()’ which do need Tcl/Tk version ‘8.6’ or higher.

Changes in R 4.6.0 Bug Fixes

• ‘chol(x, pivot=TRUE)’ now zeroes the trailing submatrix when the algorithm stops early. Following the help page instructions on how to reconstruct the matrix in positive semidefinite cases gave incorrect results if the rank was 2 or more less than the dimension (PR#15853).

• Profiling ‘"mle"’ objects (‘stats4’ package) could fail because profile MLE used starting value from full MLE. Now starts from profile MLE from previous step.

• Setting ‘attributes’ on primitive functions is now an error; previously it modified without copying (as noticed by Henrik Bengtsson on the R-devel mailing list).

  Relatedly, changing the ‘environment()’ of a primitive function does no longer happen and gives a warning (to become an error, later).

• Dataset ‘LifeCycleSavings’ had a misspelled row name: ‘"Guatamala"’ was corrected to ‘"Guatemala"’.

• The ‘Pair(x,y)’ construction in the formula interface to paired tests did not work with the ‘subset’ argument, due to the absence of a ‘[.Pair’ method, which has now been added.

• Subsetting ‘"table"’ objects keeps S3 classes more consistently, fixing PR#18845.

• When ‘browser()’ is active or when otherwise debugging, R code such as ‘if(TRUE)’ now longer triggers a new browser level, fixing PR#18885 (differently than the fix for PR#15770), with thanks to Ivan Krylov.

• ‘text()’ now truncates ‘labels’ to maximum length of ‘x’ and ‘y’ (if it is longer), fixing PR#7084. Thanks to Heather Turner, Ella Kaye, and Philippe Grosjean.

• ‘<Date> %in% set’ is again as fast as it was before R 4.3.0, _via_ a new S3 method ‘mtfrm.Date’.

  ‘<character> %in% <Date>’ and vice versa are now documented to work in concordance with ‘==’ and as an exception to the typical ‘match()’ behaviour which relies on “univariate” ‘mtfrm()’ alone.

• It is now possible to convert _to_ ‘"snpc"’ units via, e.g., ‘grid::convertWidth()’, fixing PR#18915. Thanks to Trevor Davis.

• The ‘precip’ dataset had typos in the names ‘"Bismarck"’ and ‘"Pittsburgh"’ (PR#18895).

• ‘tools::checkReplaceFuns()’ now deals better with replacement methods _not_ available as regular functions in the namespace.

• ‘length(xpr) <- n’ now also works for ‘expression’ vectors, the same as for ‘list’s, i.e., padding with ‘NULL’ entries if the length is increased. Thanks to Mikael Jagan's PR#18917.

• ‘<complex>[i] <- NA’ now only sets the _real_ part to ‘NA’, consistently with the ‘as.complex(NA)’ behaviour since R 4.4.0; thanks to Mikael Jagan's PR#18918.

• ‘format(<list>)’ calling ‘format.default()’ now calls generic ‘format()’ on each list element (rather than ‘format.default()’).

• ‘tools::Rd2HTML()’ detects paragraphs in more cases of \Sexpr-generated Rd code, fixing a regression in R 3.6.0 originally reported by Georgi Boshnakov and later also in PR#18470. An inactive #ifdef block no longer breaks the paragraph.

• Parsing a multi-line string from Rd \Sexpr code no longer doubles the newlines.

• ‘requireNamespace(.., versionCheck = *)’ now shows an error and returns ‘FALSE’ when the package version check is not fulfilled, thanks to Iris Simmons and Trevor Davis's PR#18255. Additionally, the ‘versionCheck’ argument is checked and when invalid, an error is signalled to avoid subsequent confusing error messages.

• ‘requireNamespace()’ now throws an error even if the name space is already loaded if it is called with an unmatched argument such as ‘quitely = TRUE’ or ‘quiet = TRUE’ (argument ‘quietly’ cannot be abbreviated as it follows ‘...’).

• ‘rep()’ signals more specific error messages, notably when using both ‘times’ and ‘each’ optional arguments. Fixes PR#18926, thanks to Ella Kaye and collaborators at useR! 2025's ‘R Dev Day’.

• ‘jitter(x, amount, factor)’ becomes more robust for non-finite ‘x’ or also negative ‘amount’, ‘factor’. ‘help(jitter)’ is easier to read, fixing PR#17279, thanks to its contributors.

• Plain-text help (‘Rd2txt’) lacked markup for ‘\cite’d titles, which are now wrapped in single quotes.

• Default column labels are now correctly aligned when printing a matrix with right alignment (PR#18943, thanks to Mikael Jagan).

• ‘poly(fct, n)’ signals an error again, for a non-‘ordered’ factor ‘fct’, thanks to Roland Fuss' notice on R-devel.

• ‘terms(<formula>, simplify=TRUE)’ now works correctly also in the cases where the formula has more than one term with NAs such as ‘f(u, b=NA)’ or ‘g(NA)’, finally fixing PR#15275 thanks to Mikael Jagan's patch.

• The help page ‘example(matplot)’ now correctly labels Sepal vs Petal dimensions in its first iris data plot, thanks to Jeff Dick's post on R-devel.

• ‘diff(m, lag, dif)’ for matrix ‘m’ now still returns matrices, also when ‘lag * dif > nrow(m)’ (PR#18972, thanks to Mikael Jagan and Suharto Anggono). ‘diff(<ts-matrix>)’ remains matrix, even when it has length zero.

• Values returned by active binding functions are now marked as not mutable to prevent unintended mutation in complex assignment operations.

• The default method of ‘sequence()’ now allows to fully recycle all three of ‘(nvec, from, by)’ as always documented; with thanks to Mikael Jagan's report and patch in PR#18304. Its behaviour remains back compatible for now, but can be switched to future behaviour via environment variable ‘R_sequence_recycle’, or explicit ‘recycle = TRUE’.

• Subassignment, ‘x[ind] <- val’, to 1-dimensional ‘array’s no longer “drops” them to simple vectors when ‘ind’ is a name, fixing PR#18973, reported by Thomas Soeiro.

• The ‘implicitGeneric’ definition for ‘toeplitz()’ produced a default method that failed when ‘toeplitz(x, r)’ was called with more than the first argument. Simple fix from Mikael Jagan.

• The error message for ‘array(dim = c())’ now uses ‘"'dim'"’, thanks to Hugo Gruson.

• Some legal but strange nested complex assignments are handled a bit more robustly in interpreted code.

• ‘cacheMetaData()’ does not to mangle primitive generics.

• The S4 method ‘norm(<ANY>, type = <missing>)’ for the implicit generic ‘norm()’ now uses ‘type = "O"’ as has been the intention for more than ten years, fixing PR#18979 thanks to Mikael Jagan.

• On Windows terminals ‘Ctrl-C’ now breaks out of waiting for keyboard input, fixing PR#18982.

• The default ‘summary()’ and its factor method now label missing values ‘NAs’ rather than ‘NA's’, fixing a decades-old grammatical faux pas inherited from S (PR#16348 and PR#18948).

• Asymmetric ‘toeplitz(x, r)’ is type consistent now, even when ‘r’ of length 0 or 1 is not used directly. Fixes PR#18996, thanks to Mikael Jagan's patch and test.

• ‘format(r)’ now keeps ‘names(r)’ also for raw objects ‘r’.

• ‘rep.int()’ and ‘rep_len()’ again drop names also for factors, fixing a regression in R 4.0.0. (Thanks to a report by Rui Barradas and PR#18999 by Suharto Anggono.)

• ‘str(x)’ with a ‘list’-like ‘x’ of a class having an ‘str()’ S3 method using ‘NextMethod()’, now no longer outputs ‘"List of <...>"’ in the default method, thanks to Ian Farm's report and fix proposal in PR#19001.

• ‘as.POSIXlt(ch)’, ‘as.Date(ch)’ etc now also work correctly when ‘ch’ contains ‘"Inf"’, via ‘strptime(.)’, fixing PR#19006.

• ‘c(<POSIXlt>, ..)’ now fully preserves sub-second accuracy, fulfilling a part of Suharto Anggono's wishlist PR#18989.

• The ‘"tzcode"’ attribute of ‘"POSIXlt"’ objects should no longer depend on earlier calls, fixing PR#19005 thanks to Ivan Krylov, a patch by Suharto Anggono and reports of “Non-deterministic POSIXlt tzone in Europe/London ..” on R-devel.

• In intervals with very low density ‘cdplot()’ was unreliable, returning probabilities that are greater than one or ‘NaN’ (PR#19011). Fix from Christoph Dalitz and Achim Zeileis.

• ‘R CMD build’ now installs packages providing their own vignette engine (PR#18191). Patch by Paul Smith.

• ‘ar.burg()’, ‘ar.yw()’ and ‘ar.ols()’ deal better with non finite AIC values thanks to Simone Giannerini's remarks on R-devel.