R News

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

      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).

      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

      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.

      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

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

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

      \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", such 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

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

      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

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

      does not contain a space.)

all.equal.numeric() gets a new optional switch giveErr to return the
      numeric error as attribute.  Relatedly,

      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

      correctly, e.g., in subsetting and subassignments.  Such objects
      are now documented.

      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 by using
      prettyDate(). Thanks to Swetlana Herbrandt.

The mapping of Windows' names for time zones to IANA's

      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

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 the upcoming GCC 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.

(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

      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

      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,

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

      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

      -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

      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)

      the R-devel mailing list.

as.Date.POSIXlt(x) now also works when the list components

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

Printing of a factanal() result with just one factor and sort = TRUE
      now works regularly, fixing PR#17863 by Timothy

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

      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

      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

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

      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

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

      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

      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

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

      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

      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

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_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 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 >= 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

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

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

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)

      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 +/-Inf 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

      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

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

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 >= 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

      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

      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

      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

      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

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

      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

      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

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

      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.

Libcurl-based internet access, 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

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

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

      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 endian-ness 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

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

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

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,

      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

      to work more consistently, thanks to suggestions by Suharto
      Anggono.

conformMethod() now works correctly in cases containing

      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

round() does a better job of rounding

      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

      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

      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

      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
    doc/html/NEWS.3.html and doc/html/NEWS.2.html.

