ccache/NEWS

News for ccache 3.0pre1 (unreleased)
Changes since ccache 2.4:

  UPGRADE NOTES:

    - The way the hashes are calculated has changed, so you won't get cache
      hits for compilation results stored by older ccache versions.

    - The statistics counters "files in cache" and "cache size" now only count
      object files. (Previously, files containing cached standard error output
      were counted as well.) The existing values of the two counters will be
      erroneous at first after the upgrade, but will correct themselves
      eventually when enough cleanups have been made, or when you run "ccache
      --cleanup".

    - The "max file" and "max cache size" settings now specify thresholds for
      object files count and size.

    - Because of the changes mentioned above, you might as well clear the old
      cache directory with "ccache -C" if you want, unless you plan to keep
      using an older ccache version.

  NEW FEATURES AND IMPROVEMENTS:

    - ccache now has a "direct mode" where it computes a hash of the source
      code and compiler arguments without running the preprocessor. By not
      running the preprocessor, CPU usage is reduced; the runtime is about
      0.2-1.0 times that of ccache running in traditional mode. The relative
      speedup will be higher when I/O is fast (e.g., when files are in the disk
      cache). The direct mode can be disabled by setting CCACHE_NODIRECT.

    - When hashing the output from the preprocessor, absolute paths are
      rewritten to relative paths, but only for paths under the directory
      specified by CCACHE_BASEDIR. Paths specified by -I and similar options
      get the same treatment. This is done to get cache hits even when
      compiling with -g and when using absolute include directory paths.
      Absolute paths in the standard error text will also be more accurate. The
      default value of CCACHE_BASEDIR is the current working directory. To
      disable the rewriting, set CCACHE_BASEDIR to the empty string.

    - Object files are now by default stored compressed in the cache. The
      runtime cost is negligible, and more files will fit in the ccache
      directory and in the disk cache. CCACHE_NOCOMPRESS can be set to disable
      object file compression.

    - A CCACHE_COMPILERCHECK option has been added. This option tells ccache
      what compiler-identifying information to hash to ensure that results
      retrieved from the cache are accurate. Possible values are: none (don't
      hash anything), mtime (hash the compiler's mtime and size) and content
      (hash the content of the compiler binary). The default is mtime.

    - Temporary files are now created in the directory they will end up in.
      This makes ccache more friendly to Linux's directory layout.

    - Added support for long command-line options.

    - A CACHEDIR.TAG file is now created in the cache directory. See
      <http://www.brynosaurus.com/cachedir/>.

    - Messages printed to the debug log (specified by CCACHE_LOGFILE) have been
      improved.

    - By default, ccache now puts temporary files in CCACHE_DIR/tmp to avoid
      cluttering the top directory.

    - Improved the test suite and added tests for most of the new
      functionality. It's now also possible to specify a subset of tests to
      run.

    - Standard error output from the compiler is now only stored in the cache
      if it's non-empty.

    - If the compiler produces no object file or an empty object file, but
      gives a zero exit status (could be due to a file system problem, a buggy
      program specified by CCACHE_PREFIX, etc.), ccache copes with it properly.

    - Added installcheck and distcheck make targets.

    - Clarified cache size limit options' semantics.

    - Improved display of cache max size values.

    - For debugging purposes, the variable CCACHE_VERBOSE may now be set to
      make ccache print executed commands to standard output.

  BUG FIXES:

    - Fixed build on FreeBSD.

    - Improved detection of home directory.

    - User-defined CPPFLAGS and LDFLAGS are now respected in the Makefile.

    - Fixed NFS issues.

    - Bail out on too hard compiler options --coverage, -fprofile-arcs,
      -fprofile-generate, -fprofile-use, -ftest-coverage and -save-temps. Also
      bail out on "@file" style options.

    - -MD/-MMD options without -MT/-MF are now handled correctly.

    - The -finput-charset option is now handled correctly.

    - Added support for -Wp,-MD and -Wp,-MMD options.

    - Debug information containing line numbers of predefined and command-line
      macros (enabled with the compiler option -g3) will now be correct.

    - Corrected LRU cleanup handling of object files.

    - utimes() is now used instead of utime() when available.

    - Non-writable cache directories are now handled gracefully.

    - Corrected documentation about sharing the cache directory.

    - Fixed compilation warnings from GCC 4.3.

    - The command specified by CCACHE_PREFIX is no longer part of the hash.

    - Fixed bad memory access spotted by Valgrind.

    - Fixed a bug in x_realloc.

    - Removed deprecated constructions from ccache.yo.

    - Freed memory is no longer referenced when compiling a .i/.ii file and
      falling back to running the real compiler.

    - The test suite is now immune to external values of the CCACHE_*
      environment variables.

  OTHER NOTABLE CHANGES:

    - ccache is now licensed under the GNU Public License (GPL) version 3 or
      later.