[ccache] Ccache version 4.2 has been released

[Joel Rosdahl]

Ccache version 4.2 is now available. Release archives can be found here:

    https://ccache.dev/download.html

New features:

  - Improved calculation of relative paths when using “base_dir” to also
    consider canonical paths (i.e. paths with dereferenced symlinks) as
    candidates.

  - Added a “debug_dir” (“CCACHE_DEBUGDIR”) configuration setting for
    specifying a directory for files written in debug mode.

  - Added support for compiler option “-x cuda”, understood by Clang.

  - The value of the “SOURCE_DATE_EPOCH” variable is now only hashed if it
    potentially affects the output from ccache. This means that ccache now
    (like before version 4.0) will be able to produce cache hits for source code
    that doesn't contain “__DATE__” or “__TIME__” macros regardless of the
    value of “SOURCE_DATE_EPOCH”.

Bug fixes:

  - Fixed a bug where a non-Clang compiler would silently accept the Clang-
    specific “-f(no-)color-diagnostics” option when run via ccache. This
    confused feature detection made by e.g. CMake.

  - Improved creation of temporary files on Windows. Previously, ccache would
    in practice reuse temporary filenames on said platform resulting in various
    problems with parallel builds.

  - Fixed creation of parent directories when creating a lock file on Windows.

  - Fixed a race condition related to removal of temporary files.

  - Improved calculation of directory name for a Windows-style path.

  - A compilation result is now not stored in the cache if an included
    preprocessed header file is too new. This fixes a bug where the content of
    a newly created preprocessed header file could be missing from the hash,
    resulting in a false positive cache hit.

  - Fixed calculation of the split DWARF filename for an object filename with
    zero or multiple dots.

  - Fixed retrieval of the object file the destination is “/dev/null”.

Portability and build improvements:

  - Additional compiler flags like “-Wextra -Werror” are now only added when
    building ccache in developer mode.

  - The developer build mode no longer enables “-Weverything” for Clang.

  - “_XOPEN_SOURCE” is now defined appropriately on FreeBSD to fix missing
    declaration of “isascii”.

  - Improved detection of buildability of BLAKE3 assembler files.

  - Disabled build of inode cache code on OSes without
    “pthread_mutexattr_setpshared”, such as OpenBSD.

  - Made static linking the default for a Windows MinGW build.

  - Removed legacy fallback replacements of “mkstemp” and “realpath”.

  - Improved detection of SSE/AVX support.

  - Improved detection of support for the AVX2 target attribute.

  - Configuration scripts now try to detect and enable BLAKE3's Neon support.

  - Made it possible to run the integration test suite on macOS.

  - Fixed building of 32-bit unit tests on macOS.

  - Made it possible to compile ccache for C++17.

  - Fixed printing of 64-bit “time_t” on 32-bit architectures like RISCV32.

  - Made sure to only use ASCII characters in the manual's AsciiDoc source code
    to make it possible to generate documentation in non-UTF8 locales.

  - Upgraded to optional-lite 3.4.0, fmt 7.1.3, doctest 2.4.4 and zstd 1.4.8.

  - Took steps towards being able to run the test suite on Windows.

Documentation:

  - Improved wording of “compiler_check” string values.

  - Improved documentation of compression levels and the “-X/--recompress”
    option.

  - Improved consistency of terms in the manual.

  - HTML documentation is now built and installed by default if possible.

  - Fixed incorrect documentation of configuration option “cache_dir”.

  - Added hint on how to link statically with libzstd.

  - Mention that ccache requires the “-c” compiler option.

Contributors (in alphabetical order) to this release:

  - Alexander Lanin
  - Azat Khuzhin
  - Erik Flodin
  - Joel Rosdahl
  - Ka Ho Ng
  - Khem Raj
  - Nicholas Hutchinson
  - Orgad Shaneh
  - Sergei Trofimovich
  - Stuart Henderson

Thanks!

-- Joel