# Ccache news

version 4.13.3

## Ccache 4.13.3

Release date: 2026-04-12

### New deliverables

- Added glibc binary release for Linux riscv64.
  [contributed by Ludovic Henry]

### Bug fixes and improvements

- Fixed handling of empty responses from remote storage backends: a response with an empty body is now treated as a storage error rather than a cache miss.
  [contributed by Björn Svensson]

- Fixed PCH invalidation when the MSVC toolset is updated.
  [contributed by Philipp Kolberg]

- Fixed `base_dir` path rewriting when using MSVC’s `/Yc` option: paths are no longer rewritten to relative when creating a precompiled header, since MSVC then does not like relative paths for the `/Yc` and `/FI` arguments.
  [contributed by Joel Rosdahl]

- Fixed handling of a directory-less path to the MSVC `/FI` option.
  [contributed by Joel Rosdahl]

- Added support for `-fsanitize-ignorelist` (which replaced `-fsanitize-blacklist` in Clang 13).
  [contributed by Joel Rosdahl]

- Fixed detection of type for compiler with `.` in the name (e.g. `hppa2.0-unknown-linux-gnu-gcc`).
  [contributed by Joel Rosdahl]

- Fixed `install.sh` to correctly use `sysconfdir` and other configuration variables from the Makefile.
  [contributed by Joel Rosdahl]

### Build improvements

- Changed `cmake/FindCppHttplib.cmake` to use settings from the system’s CMake config if available, supporting systems where cpp-httplib is not provided as a header-only library.
  [contributed by Jiri Slaby]

## Ccache 4.13.2

Release date: 2026-03-22

### New deliverables

- Added `tar.gz` archives for Linux binary releases.
  [contributed by Joel Rosdahl]

- Added installation script for Linux binary releases.
  [contributed by Joel Rosdahl]

### Bug fixes and improvements

- Fixed LTO handling when `-fno-lto` follows `-flto`: LTO is now properly disabled in this case.
  [contributed by Kristian Sloth Lauszus]

- Fixed crash when using MSVC `/Yc` without `/Fp`.
  [contributed by Joel Rosdahl]

- Fixed rewriting of MSVC `/FI` argument to a relative path when `base_dir` is set.
  [contributed by Joel Rosdahl]

- Improved robustness when parsing broken cache entry files.
  [contributed by Joel Rosdahl]

- Fixed atime/mtime restoration when recompressing a file.
  [contributed by Joel Rosdahl]

### Test improvements

- Fixed test failures for `remote_helper` tests when `$PWD` is long.
  [contributed by Joel Rosdahl]

- Improved robustness of `remote_helper` tests on slow systems.
  [contributed by Maksym Sobolyev]

- Relaxed `util::exec_to_string` unit test for portability.
  [contributed by Maksym Sobolyev]

- Removed unnecessary, compiler-specific checks in `-flto` tests.
  [contributed by Joel Rosdahl]

## Ccache 4.13.1

Release date: 2026-03-09

### Bug fixes and improvements

- Fixed handling of extensionless input files passed with `-x assembler` (regression in 4.13).
  [contributed by Joel Rosdahl]

- Fixed a crash when searching for a storage helper next to the ccache executable.
  [contributed by Joel Rosdahl]

- Fixed atime restoration when the recompressor fails to read a file.
  [contributed by Joel Rosdahl]

- Improved storage helper lookup order to prefer libexec directories over `PATH`.
  [contributed by Joel Rosdahl]

- Improved reliability of finding the ccache executable path by using OS-specific APIs instead of relying on `argv[0]`, which is not guaranteed to reflect the actual executable location.
  [contributed by Joel Rosdahl]

- Improved handling of `-fstack-usage` and `-fcallgraph-info` output files when LTO is used: ccache now correctly skips looking for `.su` and `.ci` files that are not generated during compilation with LTO.
  [contributed by Kristian Sloth Lauszus]

### Build fixes

- Fixed build on systems that have `utimes(2)` but not `utimensat(2)`.
  [contributed by Joel Rosdahl]

- Fixed `mktemp(1)` calls in build scripts to pass a template argument for portability to macOS/BSD.
  [contributed by Joel Rosdahl]

## Ccache 4.13

Release date: 2026-03-05

### Upgrade notes

- A C++20-capable compiler is now required to build ccache from source. Minimum supported compiler versions are GCC 10, Clang 12 and Apple Clang 10.

- Caching MSVC (`cl.exe`) compilations is now officially supported.

### New deliverables

- Added Linux binary releases statically linked with musl.
  [contributed by Joel Rosdahl]

### Removed deliverables

- Discontinued 32-bit Windows binary releases.
  [contributed by Joel Rosdahl]

### New features and improvements

- Added support for remote storage helpers: long-lived local helper processes spawned on demand for communicating with remote storage servers. Storage helpers allow support for new storage protocols to be developed and released independently of ccache. Built-in support for HTTP and Redis will likely be removed in a future release.
  [contributed by Joel Rosdahl]

- Added support for directory-specific configuration files. Ccache now looks for a `ccache.conf` file in the current working directory and its parent directories, enabling per-project configuration without modifying the user’s cache-specific config file.
  [contributed by Joel Rosdahl]

- Added `msvc_utf8` config option to allow disabling `/utf-8` for MSVC when using the fallback method of parsing preprocessed output.
  [contributed by Max Winkler]

- Added support for caching distributed ThinLTO for Clang.
  [contributed by GitHub user zcfh]

- Added support for caching MSVC `/sourceDependencies` file.
  [contributed by Joel Rosdahl]

- Added handling of Apple Clang’s `-index-unit-output-path` option.
  [contributed by Joel Rosdahl]

- Improved compiler detection on macOS by resolving the actual compiler via `$DEVELOPER_DIR` or `xcode-select` when `/usr/bin/clang(++)` shims that redirect to different compilers are used.
  [contributed by Joel Rosdahl]

- Added support for rewriting `-fcoverage-compilation-dir` and `-fcoverage-prefix-map` absolute paths (similar to existing `base_dir` rewriting).
  [contributed by Evgeniy Isaev]

- Added support for rewriting absolute paths in `-fsanitize-blacklist` option arguments.
  [contributed by Diego Alonso]

- Added support for multi-line configuration values.
  [contributed by Joel Rosdahl]

- Improved file copy performance by using `copy_file_range(2)` when available.
  [contributed by Oleg Sidorkin]

- Added `h`, `m` and `ms` as accepted time unit suffixes for `--evict-older-than` (in addition to the existing `d` and `s`).
  [contributed by Joel Rosdahl]

- Merged `--recompress-threads` and `--trim-recompress-threads` options into `--threads`. The old options are still accepted for backward compatibility.
  [contributed by Joel Rosdahl]

- Improved performance of `-x`/`--show-compression` and `-X`/`--recompress` by using threads in parallel.
  [contributed by Joel Rosdahl]

- Added logging of errors and file size changes when recompressing cache files.
  [contributed by Joel Rosdahl]

### Bug fixes

- Fixed use of monotonic clock for spin locks in the inode cache code.
  [contributed by Joel Rosdahl]

### Build improvements

- Fixed conditional enabling of the assembler language in CMake to avoid enabling both ASM and ASM_MASM on the same platform.
  [contributed by Steffen Winter]

- Fixed inclusion of `config.h` to only apply to C and C++ compilation units, not assembler files. This avoids a problem when building with Clang on Windows.
  [contributed by Joel Rosdahl]

- Disabled legacy ZSTD support when compiling ZSTD from source to avoid `-Wmaybe-uninitialized` warnings.
  [contributed by Joel Rosdahl]

- Removed check for (on POSIX) mandatory `spawn.h` header.
  [contributed by Joel Rosdahl]

### Documentation improvements

- Added generation of documentation in Markdown format.
  [contributed by Joel Rosdahl]

### Test improvements

- Added a basic integration test suite for MSVC.
  [contributed by Joel Rosdahl]

- Added an integration test for `--serialize-diagnostics`.
  [contributed by Joel Rosdahl]

- Added support for Valkey in the `remote_redis` test suite.
  [contributed by Joel Rosdahl]

- Fixed `-march=native` test to work reliably on hybrid CPU systems.
  [contributed by Joel Rosdahl]

## Ccache 4.12.3

Release date: 2026-02-07

### Bug fixes

- Fixed hashing of CWD parts of `-march=native` expansion for Clang.
  [contributed by Joel Rosdahl]

- Fixed lookup of `-march=native` expansion line for GCC on Windows.
  [contributed by Joel Rosdahl]

- Fixed rewriting of “inlined from” messages when `absolute_paths_in_stderr` is enabled.
  [contributed by Enrico Seiler]

- Added support for NVCC long option alternatives to `-M`/`-MD`/`-MF`/`-MM`/`-MMD`/`-MT`.
  [contributed by Joel Rosdahl]

- Fixed setting of `UNCACHED_ERR_FD` environment variable so that it is only set when executing the compiler.
  [contributed by Joel Rosdahl]

- Fixed leaking of inode cache file descriptor to executed programs.
  [contributed by Joel Rosdahl]

- Fixed errno check for some system calls.
  [contributed by Joel Rosdahl]

### Documentation improvements

- Fixed links to installation guide in README.
  [contributed by Evgeniy Isaev]

## Ccache 4.12.2

Release date: 2025-11-26

### Bug fixes

- Improved robustness against filesystem path encoding problems on Windows.
  [contributed by Joel Rosdahl]

- Fixed removal of mismatching manifest file.
  [contributed by Joel Rosdahl]

### Build fixes

- Fixed build of BLAKE3 for little-endian aarch64 with CMake 3.18/3.19.
  [contributed by J. Neuschäfer]

- Added linking with libsocket on SunOS/Illumos.
  [contributed by Joel Rosdahl]

### Test improvements

- Fixed profiling_clang test.
  [contributed by Evgeniy Isaev]

### Documentation improvements

- Reconciled max-size suffixes in documentation.
  [contributed by Andrej Zhilenkov]

- Improved documentation on statistics counters and --zero-stats.
  [contributed by Joel Rosdahl and Otto Kekäläinen]

- Added note that sloppiness values can be whitespace-separated.
  [contributed by Joel Rosdahl]

- Updated URLs in manual and news.
  [contributed by Joel Rosdahl]

### Other

- Fixed default sysconf dir in Linux binary releases.
  [contributed by Joel Rosdahl]

- Fixed typo in CcacheVersion.cmake.
  [contributed by Andrej Zhilenkov]

- Updated C++ standard in .clang-format.
  [contributed by Evgeniy Isaev]

## Ccache 4.12.1

Release date: 2025-10-01

### Bug fixes

- Fixed handling of `-Xarch_host`/`-Xarch_device` options.
  [contributed by Joel Rosdahl]

- Fixed saving of current position in fallocate fallback code.
  [contributed by Joel Rosdahl]

- Fixed handling of `ENOENT` when trying to break a lockfile lock.
  [contributed by Joel Rosdahl]

### Build fixes

- Added missing `return` in `copy_file_impl` fallback code, fixing a compilation error with tl::expected ≥ 1.2.0 on non-Apple platforms where `sendfile(2)` is unavailable.
  [contributed by GitHub user kingiler]

### Other

- Added missing documentation files to Linux/macOS binary releases.
  [contributed by Joel Rosdahl]

## Ccache 4.12

Release date: 2025-09-14

### Upgrade notes

- CMake version 3.18 or higher is now needed to build ccache.

### New deliverables

- Added binary releases for Linux aarch64 and Windows aarch64.
  [contributed by Joel Rosdahl and Martin Storsjö]

### New features and improvements

- Enabled awareness of long paths and wide characters on Windows by embedding an application manifest in `ccache.exe`.
  [contributed by Morten Engelhardt Olsen and Joel Rosdahl]

- Added support for multiple directories in `base_dir`/`CCACHE_BASEDIR`.
  [contributed by Joel Rosdahl]

- Added support for Clang compiling CUDA code.
  [contributed by GitHub user w169Nq169]

- Added support `-x cu` and `-x cuda` in Clang CUDA mode.
  [contributed by GitHub user w169q169]

- Added support for Clang’s `--config=` option.
  [contributed by Joel Rosdahl]

- Added logging of process exit.
  [contributed by Joel Rosdahl]

- Added logging of mtime for files removed from the internal temporary directory.
  [contributed by Joel Rosdahl]

- Added logging of URLs requested by the http storage backend.
  [contributed by Joel Rosdahl]

- Improved logging of manifest lookup.
  [contributed by Joel Rosdahl]

- Improved logging of executed processes.
  [contributed by Joel Rosdahl with a fix by Leander Schulten]

### Removed features

- Removed support for avoiding the second preprocessor call (`run_second_cpp=false`/`CCACHE_NOCPP2`). This feature added complexity while offering little practical value, as it was rarely used and modern compilers have increasingly poor support for compiling preprocessed source code. The maintenance cost therefore outweighed the benefit of keeping it.
  [contributed by Joel Rosdahl]

### Bug fixes

- Fixed handling of compiler arguments so that ccache now preserves their original order, resolving issues where order-sensitive options such as `-Werror` could be reordered.
  [contributed by Joel Rosdahl]

- Implemented expansion of system-dependent `-m{arch,cpu,tune}=native` options to prevent false cache hits when compiling on different hardware.
  [contributed by Joel Rosdahl]

- Fixed rewriting of absolute paths to relative (with `base_dir` in effect) so that paths with dereferenced symlinks are no longer considered as candidates.
  [contributed by Joel Rosdahl]

- Fixed compiler detection to check Clang before GCC for `cc`/`c++` hard links.
  [contributed by Joel Rosdahl]

- Fixed hashing of GCC specs file. Previously specs files located in system directories could not be found.
  [contributed by Joel Rosdahl]

- Added MSVC variables `INCLUDE` and `EXTERNAL_INCLUDE` to the input hash since they affect compilation.
  [contributed by Joel Rosdahl]

- Fixed bad conversion from UTF-16 when reading files on Windows.
  [contributed by Leander Schulten]

- Removed misleading logging of failure to remove output file in hard link mode.
  [contributed by Joel Rosdahl]

### Build improvements

- Made ccache link statically with libatomic when STATIC_LINK is set.
  [contributed by Maksym Sobolyev]

- Made ccache buildable with tl-expected 1.2.0.
  [contributed by Joel Rosdahl]

- The bundled copy of libfmt is now used as documented if `DEPS=DOWNLOAD`.
  [contributed by Joel Rosdahl]

- Switched to use `FetchContent_MakeAvailable` instead of `FetchContent_Populate` to avoid warnings with newer CMake versions.
  [contributed by Joel Rosdahl]

- Set variables to avoid a warning from downloaded zstd’s CMake scripts.
  [contributed by Joel Rosdahl]

- Added CMake toolchain file for (cross) compilation to aarch64-w64-mingw32.
  [contributed by Martin Storsjö]

- Disabled use of BLAKE3 NEON code on big-endian aarch64 since only little-endian is supported.
  [contributed by Jontathan Neuschäfer]

### Test improvements

- Added test for tricky preprocessed cache hit case.
  [contributed by Joel Rosdahl]

- Fixed calculation of root directory to avoid crashes on some Windows systems.
  [contributed by Leander Schulten]

### Documentation improvements

- Documented that the direct mode has now (since ccache 4.10) less risk to read headers from incorrect locations.
  [contributed by Joel Rosdahl]

- Documented that `#pragma once` can be problematic with precompiler headers (PCH).
  [small]#[contributed by Joel Rosdahl]#

- Added missing documentation of `"Unsupported source encoding"` statistics counter.
  [contributed by Joel Rosdahl]

## Ccache 4.11.3

Release date: 2025-05-03

### Bug fixes

- Fixed handling of Apple Clang `-Xpreprocessor -fopenmp` options (regression in ccache 4.10).
  [contributed by Joel Rosdahl]

### Build improvements

- Adapted unit test code to compile with doctest 2.4.12.
  [contributed by Joel Rosdahl]

### Test improvements

- Silenced benign compiler warning in the profiling_gcc_10+ suite.
  [contributed by Joel Rosdahl]

## Ccache 4.11.2

Release date: 2025-03-22

### Bug fixes

- Reset signal mask and signal defaults when executing compiler. This fixes a problem where interrupting the compilation (e.g. with Ctrl+C) wouldn’t kill the compiler (regression in ccache 4.11).
  [contributed by Joel Rosdahl]

## Ccache 4.11.1

Release date: 2025-03-17

### Bug fixes

- Fixed erroneous log file locking on Windows (regression in ccache 4.11).
  [contributed by Joel Rosdahl]

## Ccache 4.11

Release date: 2025-03-09

### New features and improvements

- Added ability to send arbitrary HTTP headers to HTTP storage.
  [contributed by GitHub user dsrowell]

- Added support for MSVC’s `/TC` and `/TP` options.
  [contributed by Huang Qin Jin]

- Made the `absolute_paths_in_stderr` feature also handle MSVC diagnostics messages.
  [contributed by Huang Qin Jin]

- Absolute paths in MSVC diagnostics messages are now rewritten to relative if `base_dir` is in effect.
  [contributed by Huang Qin Jin]

- Added support for NVCC’s `--compile` option.
  [contributed by Laurent Bouhier]

- `posix_spawn` is now used instead `execv` to execute the compiler on POSIX systems.
  [contributed by Brendan Shanks]

- Added support for GCC’s `-fprofile-prefix-path` option.
  [contributed by Dávid Péter Jánosa]

- Added `response_file_format` config option to control response file format.
  [contributed by Max Winkler]

- Added support for Clang `-frandomize-layout-seed-file` option.
  [contributed by Joel Rosdahl]

- Improved `absolute_paths_in_stderr` to recognize more paths patterns.
  [contributed by GitHub user gitmodimo]

- Added support for the clang-cl option `/showIncludes:user`.
  [contributed by Joel Rosdahl]

- Added support for Intel’s LLVM-based compilers `icx` and `icx-cl`.
  [contributed by Nick Sarnie]

- A stat call for `~/.ccache` is now avoided if `CCACHE_DIR` is set.
  [contributed by Joel Rosdahl]

- Added Support for `.bat` and `.cmd` scripts as the compiler on Windows.
  [contributed by GitHub user Doekin]

- Added support for Clang’s `-f{debug,file}-compilation-dir` options.
  [contributed by Henrique Ferreiro]

- Added knowledge about Clang’s `--offload-compress` option. This will avoid errors when ccache runs the compiler in preprocessor mode.
  [contributed by Icarus Sparry]

- Added knowledge about Clang options `-fmodules-cache-path`, `-fmodule-map-file` and `-fbuild-session-file`.
  [contributed by GitHub user kzlar]

### Bug fixes

- Improved handling of paths internally, thereby fixing some issues on Windows (for example when using non-ASCII paths).
  [contributed by Joel Rosdahl]

- Fixed interpretation of non-ASCII paths in environment variables on Windows.
  [contributed by Joel Rosdahl]

- Made sure that remote storage `keep-alive` can be overridden as expected.
  [contributed by GitHub user moha-gh]

- Fixed detection of compiler type for hard-linked generic compiler name.
  [contributed by Joel Rosdahl and GitHub user Desour]

- Fixed problems with matching a path with `base_dir` if either ends with a slash.
  [contributed by Joel Rosdahl]

- The `-fprofile-abs-path` option is now correctly passed through to GCC.
  [contributed by Matt Johnston]

- Writes to the log file are now synchronized.
  [contributed by Joel Rosdahl]

- Command line config options ending with “/ccache” are now handled properly.
  [contributed by Joel Rosdahl]

- Made `--trim-method mtime` actually use mtime instead of atime.
  [contributed by Joel Rosdahl]

- Fixed a bug where ccache failed to rename raw files correctly for large caches that have more than two cache levels.
  [contributed by Oded Shimon]

### Build improvements

- Instructed MSVC to accept UTF-8 characters in ccache’s own source code.
  [contributed by Huang Qin Jin]

- Fixed binary patching of `sysconfdir` for the prebuilt Linux binary.
  [contributed by Joel Rosdahl]

- Added an `HTTP_STORAGE_BACKEND` build option to make it possible to turn off the http storage backend.
  [contributed by Maksym Sobolyev]

- Fixed call to `sha256sum` on macOS.
  [contributed by Henrique Ferreiro]

### Test improvements

- Made tests pass in year 2038.
  [contributed by Bernhard M. Wiedemann]

- Refreshed some Dockerfiles.
  [contributed by Maksym Sobolyev]

### Documentation improvements

- Added documentation saying that `absolute_paths_in_stderr` also applies to stdout.
  [contributed by Joel Rosdahl]

- Fixed description of `default cache_dir` on non-macOS POSIX systems.
  [contributed by Joel Rosdahl]

- Clarified how ccache’s LRU cleanup works.
  [contributed by Joel Rosdahl]

## Ccache 4.10.2

Release date: 2024-07-22

### Build improvements

- Fixed detection of Fmt version 11 and newer.
  [contributed by Holger Hoffstätte and Joel Rosdahl]

### Test improvements

- Made the “-fprofile-update=atomic” test only run when that option is supported by the compiler.
  [contributed by Joel Rosdahl]

- Made the color diagnostics tests work when the user running the tests has a non-POSIX login shell.
  [contributed by Anders F Björklund]

## Ccache 4.10.1

Release date: 2024-06-30

### Bug fixes

- Fixed prefix command lookup from `PATH`.
  [contributed by Romain Geissler]

### Build improvements

- Fixed detection and usage of system blake3.
  [contributed by Carlo Cabrera]

- Find CppHttplib named libhttplib.so as well.
  [contributed by Sam James]

- Removed Xcode assembly workaround for zstd.
  [contributed by Gregor Jasny]

- Added bundled subset of Fmt again for convenience.
  [contributed by Joel Rosdahl]

- Removed no longer needed workaround when building downloaded Zstd.
  [contributed by Joel Rosdahl]

### Documentation improvements

- Clarified that `--set-config` writes to the configuration file.
  [contributed by Joel Rosdahl]

## Ccache 4.10

Release date: 2024-05-29

### New features and improvements

- Added support for GCC option `-fcallgraph-info`.
  [contributed by Raihaan Shouhell]

- Added support for GCC option `-fprofile-update`.
  [contributed by Raihaan Shouhell]

- Added support for GCC option `-fdump-ipa-clones`.
  [contributed by Jiri Slaby]

- Added support for the MSVC `/Yc` option (precompiled header).
  [contributed by Clemens Wasser, Thomas Ferrand and Silver Zachara]

- Added support for the MSVC `/Tc<path>` and `/Tp<path>` options (specifying source code type).
  [contributed by Joel Rosdahl]

- Added an experimental inode cache implementation for Windows. This speeds up ccache a lot when many headers are included, both for cache hits and cache misses.

  | This feature is currently disabled by default, but interested Windows users are encouraged to try it out by setting inode_cache = true.

  [contributed by Thomas Ferrand]

- Added knowledge of Xcode option `-ivfsstatcache`.
  [contributed by Joel Rosdahl]

- Added support for Apple Clang option `-Xpreprocessor -fopenmp` in direct mode.
  [contributed by Joel Rosdahl]

- Added knowledge of Emscripten option `--em-config`.
  [contributed by Byoungchan Lee]

- Reduced the risk of false positive direct mode hits.
  [contributed by Joel Rosdahl]

- Clear direct mode manifest on recache.
  [contributed by Joel Rosdahl]

- Optimized file reading on Windows.
  [contributed by Clemens Wasser]

- Optimized file copying performed when hard linking or file cloning is enabled.
  [contributed by Raihaan Shouhell]

- Use `posix_spawn(3)` for executing compiler check commands.
  [contributed by Brendan Shanks]

- The prefix_command and prefix_command_cpp configuration options now allow any prefix, not only programs that exist in `PATH`. This means that prefix_command now can be a program with arguments.
  [contributed by Joel Rosdahl]

- Added a new `incbin` sloppiness value for ignoring presence of `.incbin` directives in the source code.
  [contributed by Raihaan Shouhell]

- Added a `--print-log-stats` option that prints a machine-parsable variant of `--show-log-stats`.
  [contributed Kaspar Schleiser]

- Added a `--format` option for selecting JSON or tab format for `--print-stats` and `--print-log-stats`.
  [contributed Kaspar Schleiser]

- Added a `--print-version` option for printing ccache version in machine-parsable format.
  [contributed by Silver Zachara]

- The `--inspect` option now retains access time (atime) of the inspected file if possible.
  [contributed by Joel Rosdahl]

### Bug fixes

- Fixed reading of files larger than 231 bytes on some systems where this was a problem.
  [contributed by Joel Rosdahl]

- Improved handling of large files on 32-bit systems.
  [contributed by Joel Rosdahl]

- Nonexistent include files are allowed in preprocessor mode again, fixing regression in ccache 4.9.1.
  [contributed by Joel Rosdahl]

- The Clang `-fdiagnostics-color` option is now handled again, fixing regression in ccache 4.6.2.
  [contributed by Joel Rosdahl]

- Fixed assertion failure on Windows mapped network drives.
  [contributed by Joel Rosdahl]

- Fixed handling of MSVC options `/Fp` and `/Yu`.
  [contributed by Silver Zachara]

- Fixed lock file implementation on MSYS2.
  [contributed by GitHub user Kreijstal]

- The “apparent real path” of the object file is now added to the input hash when using `-fprofile-arcs` to avoid false positive hits in some scenarios.
  [contributed by Joel Rosdahl]

- When generating profiling information, run_second_cpp is now forced to true so that the coverage report won’t refer to a temporary preprocessed file.
  [contributed by Joel Rosdahl]

### Build improvements

- Improved handling of ccache dependencies. A new `DEPS` CMake variable selects how software library dependencies should be located or retrieved, replacing the old `HIREDIS_FROM_INTERNET`, `ZSTD_FROM_INTERNET` and `OFFLINE` variables. Options are `AUTO` (the default) for automatically downloading missing dependencies, `DOWNLOAD` for always downloading and `LOCAL` for never downloading. See Software library dependencies for details.
  [contributed by Joel Rosdahl]

- Added support for using a local installation of BLAKE3, cpp-httplib, nonstd-span and tl-expected instead of linking to bundled copies.
  [contributed by Joel Rosdahl]

- Removed bundled copies of doctest, fmt, getopt_long and xxhash.
  [contributed by Joel Rosdahl]

- Changed to use the Windows BLAKE3 implementation when building on MSYS2.
  [contributed by Joel Rosdahl]

### Documentation improvements

- Improved documentation of “gcno_cwd sloppiness”.
  [contributed by Joel Rosdahl]

## Ccache 4.9.1

Release date: 2024-02-05

### Bug fixes

- Improved detection of bad remote storage URLs gracefully. This also fixes crashes seen in ccache’s own test suite.
  [contributed by Joel Rosdahl]

- Made caching completely disabled when modification of a source or include file is detected during ccache invocation. Previously this was only done for the direct mode.
  [contributed by Joel Rosdahl]

- Fixed an MSVC crash when using `/Zi` with many concurrent compilations.
  [contributed by Joel Rosdahl]

- Fixed a crash when `-arch` is the last compiler option.
  [contributed by Joel Rosdahl]

## Ccache 4.9

Release date: 2023-12-30

### New features and improvements

- Made `ignore_options`/`CCACHE_IGNOREOPTIONS` also skip the option from special processing, similar to how `--ccache-skip` works.
  [contributed by Joel Rosdahl]

- Added support for expanding environment variables references in all configuration options.
  [contributed by GitHub user cupu]

- MSVC options `/Fd`, `/FS` and `/MP` are no longer included in the input hash.
  [contributed by Huang Qin Jin]

- Made ccache terminate an ongoing compiler subprocess when terminated on all platforms, not only on Unix.
  [contributed by Andreas Reischuck]

- Added support for multiple `-Xarch_*` arguments matching `-arch`.
  [contributed by Tadej Novak]

- Added a `debug_level`/`CCACHE_DEBUGLEVEL` configuration option, making it possible to tell ccache to only write a log file for each compilation, not other debug files.
  [contributed by GitHub user dsilakov]

- Added `max_cache_size_kibibyte` and `max_files_in_cache` fields in output from `ccache --print-stats`.
  [contributed by Joel Rosdahl]

- Paths after `-Xclang -include` are now rewritten to relative paths if `base_dir`/`CCACHE_BASEDIR` is in effect.
  [contributed by Jiulong Wang]

- Added support for `clang --analyze`.
  [contributed by GitHub user mbel]

- Improved processing of input file arguments.
  [contributed by Joel Rosdahl]

- Added support for `st_Xtimensec` fields in `struct stat`, thus improving behavior on some BSDs when using newly created include files.
  [contributed by Joel Rosdahl]

- Added support for the undocumented GCC/Clang option `--include`.
  [contributed by Joel Rosdahl]

### Bug fixes

- Ccache now exits more gracefully on invalid sharded remote storage URLs.
  [contributed by Joel Rosdahl]

- Made ccache bail out on too hard options `-fmodules-ts`, `-fmodule-header`, `-wrapper` and `-Xclang -ast-dump`.
  [contributed by Joel Rosdahl]

- Stopped relying on the `st_blocks` field in `struct stat` since it cannot be trusted for filesystems such as ZFS that do transparent compression or deduplication and adjust `st_blocks` some time in the future.
  [contributed by Joel Rosdahl]

- Fixed crash on Windows for paths with only a drive letter.
  [contributed by Martin Blanchard]

- Made handling of Clang config options (such as `--config-system-dir`) more robust.
  [contributed by Joel Rosdahl]

- Fixed compiler type detection when compiler is a symlink called “clang-cl”.
  [contributed by GitHub user DarkShadow44]

- Made sure to use MSVC logic for `clang-cl` when handling a precompiled header.
  [contributed by GitHub user DarkShadow44]

- Generalized expansion of remote storage URLs with sharding, for instance making it possible to shard on port number.
  [contributed by Joel Rosdahl]

### Build improvements

- Upgraded to xxHash 0.8.2, thereby fixing an error when compiling ccache with `-Og`.
  [contributed by Joel Rosdahl]

- Fixed sign-compare warning in `src/InodeCache.cpp` on FreeBSD.
  [contributed by Joel Rosdahl]

- Fixed the CMake option `STATIC_LINK` on Linux/macOS.
  [contributed by Rafael Kitover]

- Added the CMake option `OFFLINE`, defaulting to the value of the standard variable `FETCHCONTENT_FULLY_DISCONNECTED` (which is OFF by default), to disable downloading anything from the internet.
  [contributed by Rafael Kitover]

- Fixed warnings about unused functions on new MSVC versions.
  [contributed by Rafael Kitover]

- Made sure to set both C and C++ CMake compiler launcher variables if either is set.
  [contributed by Rafael Kitover]

### Documentation improvements

- The manual now mentions that `system_headers` sloppiness is not supported for MSVC.
  [contributed by Joel Rosdahl]

### Test improvements

- Fixed regex in direct.bash.
  [contributed by Viktor Szépe]

### Other improvements

- Remove duplicated call to `posix_spawn_file_actions_init`.
  [contributed by Juan Manuel Martinez Caamaño]

## Ccache 4.8.3

Release date: 2023-08-29

### Bug fixes

- Fixed various problems with parsing of MSVC response file (`.rsp`).
  [contributed by Jiri Hörner]

- Fixed handling of NVCC `-Xcompiler` and `--Werror` options.
  [contributed by Andrew Hardin]

- Fixed bookkeeping of files when hard linking or file cloning is enabled. In ccache 4.8–4.8.2 this could result in incorrect size/count statistics after automatic or explicit cleanup.
  [contributed by Joel Rosdahl]

### Build improvements

- Made a workaround for GCC 12.3 bug 109241 where GCC fails to compile ccache.
  [contributed by Joel Rosdahl]

- Upgraded to xxHash 0.8.2, which fixes compilation of ccache with GCC 12 and `-Og`.
  [contributed by Joel Rosdahl]

## Ccache 4.8.2

Release date: 2023-06-12

### Bug fixes

- Fixed parsing of Windows drive letter in file URLs for remote storage.
  [contributed by Joel Rosdahl]

- Fixed a bug affecting depend mode with MSVC.
  [contributed by Huang Qin Jin]

- Ccache no longer passes `-v` to the preprocessor. This improves preprocessor mode hit rate when `-v` is on the compiler command line.
  [contributed by Joel Rosdahl]

- Made `--trim-max-size` accept 0 for no limit.
  [contributed by Joel Rosdahl]

### Build improvements

- Made various fixes for Windows 64-bit MSBuild builds.
  [contributed by Rafael Kitover]

- Silenced CMake warning for extracted timestamps.
  [contributed by Rafael Kitover]

- Worked around problem with building ZStandard with Xcode.
  [contributed by Gregor Jasny]

- Fixed undefined behavior (only triggered by unit tests) in `util::read_file_part` for zero count, making the build fail with `_GLIBCXX_ASSERTIONS`.
  [contributed by Joel Rosdahl]

### Documentation improvements

- Clarified `--evict-older-than` semantics.
  [contributed by Joel Rosdahl]

### Test improvements

- Fixed typo in “Directory is not hashed if using -gz” test.
  [contributed by Sam James]

## Ccache 4.8.1

Release date: 2023-05-19

### Bug fixes

- Fixed an issue with the depend mode in combination with `--` on the command line for Clang-based compilers.
  [contributed by Joel Rosdahl]

- Improved knowledge about MSVC debug flags so that non-debug `/Z*` options are once again supported.
  [contributed by Stephan Rohmen]

- Ccache no longer treats `/Zi` as unsupported for clang-cl.
  [contributed by Tobias Hieta]

- Made the output format of `ccache -k max_size` parsable by ccache itself.
  [contributed by Joel Rosdahl]

### Build/CI improvements

- Corrected ccache version in the macOS binary release.
  [contributed by Joel Rosdahl]

- Made it possible to build ccache with clang-cl on Windows.
  [contributed by Tobias Hieta]

- Upgraded to doctest 2.4.11, thereby fixing a build issue on Solaris.
  [contributed by Joel Rosdahl]

### Documentation improvements

- Added a remote file storage example with URL-encoded spaces.
  [contributed by Joel Rosdahl]

## Ccache 4.8

Release date: 2023-03-12

### New features and improvements

- Improved the automatic cache cleanup mechanism. Automatic cleanups are now performed on 1/256 of the cache instead of 1/16, thus making them much quicker (but naturally more frequent). Cleanups are coordinated between ccache processes so that at most one process will perform cleanup at a time. Also, the actual cache size will stay very close to the configured maximum size instead of staying around 90% as was the case before.
  [contributed by Joel Rosdahl]

- Added support for setting per-compilation configuration options on the command line. Example: `ccache hash_dir=false gcc -c example.c`.
  [contributed by Joel Rosdahl]

- Made it possible to disable ccache for a certain source code file by embedding the string `ccache:disable` in a comment near the top of the file.
  [contributed by Joel Rosdahl]

- Made ccache understand that an MSVC `/Z7` option overrides an earlier `/Z*` option and thus is not too hard to cache.
  [contributed by Joel Rosdahl]

- Added a `--recompress-threads` command line option for selecting the number of CPU threads to use when recompressing the local cache.
  [contributed by Joel Rosdahl]

- Added `--trim-recompress` and `--trim-recompress-threads` command line options for recompressing file-based remote storage.
  [contributed by Joel Rosdahl]

- Added tmpfs, ufs and zfs to the list of supported filesystems on macOS and BSDs for the inode cache.
  [contributed by Oleg Sidorkin]

- Improved progress bars for clean/clear/evict-style operations.
  [contributed by Joel Rosdahl]

- Improved printing of cache sizes in various outputs.
  [contributed by Joel Rosdahl]

- Activate debug logging for command mode options like `--cleanup`.
  [contributed by Joel Rosdahl]

- Added support for `-Wp,-U<macro>` in the direct mode.
  [contributed by Joel Rosdahl]

- Added quotes around arguments with space in logged command lines.
  [contributed by Joel Rosdahl]

- Added logging of executed command lines on Windows.
  [contributed by Joel Rosdahl]

- Made sure not to update the stats file when there are no incremented counters.
  [contributed by Joel Rosdahl]

- Improved actual disk size calculation on Windows.
  [contributed by Joel Rosdahl]

### Build/CI improvements

- Added CI support for building macOS universal binaries.
  [contributed by Raihaan Shouhell]

- Make it possible to force download of Zstd and Hiredis, e.g. with `cmake -D ZSTD_FROM_INTERNET=ON […​]`.
  [contributed by Joel Rosdahl]

### Bug fixes

- Fixed an edge case where a non-temporal identifier is misidentified.
  [contributed by Erik Flodin]

- Fixed reporting of local/remote cache misses in depend mode.
  [contributed by Joel Rosdahl]

- Fixed parsing of backslashes in MSVC RSP files.
  [contributed by Raihaan Shouhell]

- Fixed a crash in `--show-log-stats` when the stats log file doesn’t exist.
  [contributed by Joel Rosdahl]

- Fixed matching of base directory for MSVC. The base directory will now match case-insensitively with absolute paths in preprocessed output, or from `/showIncludes` in the depend mode case, when compiling with MSVC.
  [contributed by Joel Rosdahl]

- Fixed a problem where the original umask would be used when storing a remote cache result in the local cache.
  [contributed by Joel Rosdahl]

- Changed the inode cache implementation to use spinlocks instead of pthread mutexes. This makes the inode cache work on FreeBSD and similar systems.
  [contributed by Oleg Sidorkin]

- Don’t treat `-Wp,-D` as interchangeable with `-D`.
  [contributed by Joel Rosdahl]

- Disable the inode cache if the filesystem risks getting full soon. This fixes a problem when the cache is on a filesystem where `posix_fallocate` isn’t reliable, like Btrfs with compression enabled.
  [contributed by Joel Rosdahl]

- Fixed performance of cache path relativization in preprocessed output, primarily on Windows where `stat` calls are relatively costly.
  [contributed by Joel Rosdahl]

- Fixed rare crash in the signal handler at process exit.
  [contributed by Joel Rosdahl]

- Fixed handling of Unix-style paths passed to MSVC.
  [contributed by Joel Rosdahl]

- Fixed so that the config options and command line are logged before trying to locate the compiler and exiting early.
  [contributed by Joel Rosdahl]

### Documentation improvements

- Improved description of `--set-config`.
  [contributed by Joel Rosdahl]

- Fixed broken markup in the manual.
  [contributed by Joel Rosdahl]

- Added a note to the manual that `stats = false` will disable automatic cleanup.
  [contributed by Joel Rosdahl]

- Fix a bad reference to the “Remote storage backends” section.
  [contributed by Joel Rosdahl]

## Ccache 4.7.5

Release date: 2023-03-20

### Bug fixes

- Disabled the inode cache by default again since there have reports of ccache processes hanging on futex calls related to the inode cache.
  [contributed by Joel Rosdahl]

## Ccache 4.7.4

Release date: 2022-11-21

### Bug fixes

- Fixed an inode cache race condition.
  [contributed by Joel Rosdahl]

- The default temporary directory is now `$XDG_RUNTIME_DIR/ccache-tmp` instead of a hardcoded `/run/user/<UID>/ccache-tmp`. If `XDG_RUNTIME_DIR` is not set, `<cache_dir>/tmp` is used. This avoids creating `/run/user/<UID>` on systems that don’t have it if compiling as root.
  [contributed by Joel Rosdahl and Oleg Sidorkin]

- Added a fallback in case `posix_fallocate` returns `EINVAL` when creating the inode cache file.
  [contributed by Oleg Sidorkin]

- Connection timeout for an HTTP connection is now reported as a timeout instead of an error.
  [contributed by Joel Rosdahl]

- Temporary files found in the cache are no longer counted in `--show-compression`.
  [contributed by Joel Rosdahl]

- Removed duplicate magic header in output from `--inspect`.
  [contributed by Joel Rosdahl]

- Ccache now properly waits for all recompression jobs to finish when there is no `f` subdirectory in the cache.
  [contributed by Joel Rosdahl]

### Other minor improvements

- Improved inode cache logging.
  [contributed by Joel Rosdahl]

### Documentation improvements

- Removed stray parenthesis.
  [contributed by Joel Rosdahl]

- Improved description of how header files are handled.
  [contributed by Joel Rosdahl]

- Added a hint about using `-fno-pch-timestamp` for precompiled headers with Clang.
  [contributed by Joel Rosdahl]

- Removed obsolete description of compiler type “pump”.
  [contributed by Joel Rosdahl]

## Ccache 4.7.3

Release date: 2022-11-05

### New features and improvements

- Re-added support for handling a `-Wp,-MD` or `-Wp,-MMD` option with `-o` but without `-MMD`, `-MQ` or `-MT` for GCC and Clang. (This combination of options is used by the Linux kernel build system and became unsupported as a side-effect of a feature added in ccache 4.7.)
  [contributed by Joel Rosdahl]

- Variables that affect Clang version on macOS are now added to the input hash.
  [contributed by Joel Rosdahl]

- Variables that affect the underlying compiler used by ICC (the Intel compiler) are now added to the input hash.
  [contributed by Joel Rosdahl]

### Bug fixes

- Fixed parsing of sloppiness with a trailing delimiter.
  [contributed by Joel Rosdahl]

### Other minor improvements

- Removed a redundant slash in URLs when querying remote HTTP storage.
  [contributed by Joel Rosdahl]

- Improved logging related to the inode cache.
  [contributed by Joel Rosdahl]

### Documentation improvements

- Added documentation of the default value of keep_comments_cpp.
  [contributed by Joel Rosdahl]

### Test improvements

- Silenced various benign test warnings.
  [contributed by Joel Rosdahl]

## Ccache 4.7.2

Release date: 2022-10-29

### Bug fixes

- Fixed a problem when using 32-bit and 64-bit ccache binaries with the same inode cache file.
  [contributed by Joel Rosdahl]

- Ccache now processes the argument following a `-Xarch` option.
  [contributed by Keith Buck]

- Made sure to use the configured umask for command line operations like `--zero-stats` so that newly created cache directories will have correct permissions.
  [contributed by Joel Rosdahl]

### Build improvements

- Include `limits.h` for `PATH_MAX`.
  [contributed by Joel Rosdahl]

### Test improvements

- Disabled flaky Windows profiling tests.
  [contributed by Joel Rosdahl]

## Ccache 4.7.1

Release date: 2022-10-22

### Bug fixes

- Fixed a regression in 4.7 related to using the `-MD` or `-MMD` option when compiling an assembler file.
  [contributed by Joel Rosdahl]

### Build improvements

- Added support for compiling ccache with GCC 8.
  [contributed by Orgad Shaneh]

- Removed unneeded C++11 flag in libatomic test.
  [contributed by Orgad Shaneh]

## Ccache 4.7

Release date: 2022-10-17

### Compatibility notes

- The cache entry format has changed, so ccache 4.7 will not share cache entries with earlier versions. Different ccache versions can however still use the same cache storage without any issues.

- The default location of the cache directory on Windows has been changed from `%APPDATA%\ccache` to `%LOCALAPPDATA%\ccache`. Please remove any existing `%APPDATA%\ccache` directory or move it to `%LOCALAPPDATA%\ccache` to keep it.

### Changed tooling

- A C++17 compiler and CMake 3.15 or newer are now required to build ccache.

### New and improved features

- The inode cache is now enabled by default, but only if the filesystem where ccache’s temporary directory is located is known to work with the inode cache.
  [contributed by Joel Rosdahl]

- Improved performance of cache entry reading and writing.
  [contributed by Joel Rosdahl]

- Added a remote_only configuration option, which tells ccache to disable local storage. This way, ccache can use a shared network cache without writing cache entries locally, which can be useful if the local storage is ephemeral.
  [contributed by Joel Rosdahl]

- Renamed configuration option secondary_storage to remote_storage. The old spelling will still work as a deprecated alias.
  [contributed by Joel Rosdahl]

- Improved handling of manifests when using both local and remote storage.

  On a cache miss, ccache used to update the local manifest file and write it to remote storage, thereby overwriting any preexisting manifest entries on remote storage. Similarly, the local manifest could be replaced by the remote manifest on a remote cache hit, thus discarding local entries. This has now been improved so that ccache will merge local and remote manifest entries transparently.
  [contributed by Joel Rosdahl and GitHub user bengtj]

- Added support for caching assembler listing files with compiler option `-Wa,-a=file`. This also fixes a bug in ccache 4.6.2+ where usage of `-Wa,-march=…​` makes ccache fall back to running the compiler.
  [contributed by Joel Rosdahl]

- Improved statistics shown by `ccache --show-stats`. Most values are now shown in relation to a total count, and some less useful statistics counters have been changed to be displayed only with `--verbose`.
  [contributed by Joel Rosdahl]

- Improved statistics for remote hits and misses.
  [contributed by Joel Rosdahl]

- Renamed “Primary config” to “Config file” and “Secondary config” to “System config file” in the output of `ccache --show-stats --verbose`.
  [contributed by Joel Rosdahl]

- Added support for masquerading as a compiler via a copy or hard link of the ccache executable. Previously, ccache only supported masquerading as a compiler by using a symbolic link.
  [contributed by Joel Rosdahl]

- A timestamp is now included in per-object debug filenames. This makes it easier to compare two builds without having to save previous debug files before the second build. It also makes sure debug files won’t be overwritten if an object file is compiled several times during one build.
  [contributed by Joel Rosdahl]

- Added support for Clang’s `--` option.
  [contributed by Joel Rosdahl]

- Cache entries are now shared for different `-MT`/`-MQ` options.
  [contributed by Joel Rosdahl]

- The default location of the cache directory on Windows has been changed to `%LOCALAPPDATA%\ccache`, both in Windows Bash and Windows native environments such as CMD or Powershell.

  Previous ccache versions defaulted to storing the cache in `%APPDATA%\ccache` on Windows in native environment (i.e., when the `%USER%` variable was not set), which could result in large network file transfers of the cache in domain environments and similar problems.
  [contributed by Rafael Kitover]

- Ccache now uses subsecond resolution timestamps when checking for “too new include files”. In practice, this means that the direct mode will no longer be disabled for newly generated include files.
  [contributed by Joel Rosdahl]

- Started using subsecond resolution timestamps in manifest files. This improves accuracy with file_stat_matches sloppiness.
  [contributed by Joel Rosdahl]

- Added support for subsecond timestamps on macOS.
  [contributed by Joel Rosdahl]

- Added depend mode support for MSVC.
  [contributed by Orgad Shaneh and Luboš Luňák]

- Added support for the Intel compiler on Windows.
  [contributed by Daniel Richtmann]

- Ccache now sets `CCACHE_DISABLE` when running the compiler. This avoids running ccache twice (and potentially storing two different results in the cache) if, for instance, the compiler happens to be a wrapper script that in turn runs `ccache $compiler …​`.
  [contributed by Joel Rosdahl]

- Added support for Redis over Unix sockets.
  [contributed by Anders F Björklund]

- Added support for GCC’s `-fprofile-abs-path` option by including the current working directory in the input hash. To opt out of this, set gcno_cwd sloppiness.
  [contributed by Joel Rosdahl]

- Made it possible to exclude `-frandom-seed=seed` options from the input hash with a new random_seed sloppiness.
  [contributed by Raihaan Shouhell]

- Added support for server name in remote storage file URLs on Windows.
  [contributed by Joel Rosdahl]

- Configuration file locations are now included in the debug log.
  [contributed by Joel Rosdahl]

- The inode cache file is no longer removed with `ccache --clear`.
  [contributed by Joel Rosdahl]

- Result format version and number of files are now printed when inspecting a result cache entry file.
  [contributed by Joel Rosdahl]

### Removed features

- Removed the share-hits attribute for remote storage. It has been superseded by the remote_only configuration option.
  [contributed by Joel Rosdahl]

- Buggy support for GCC-specific environment variables `DEPENDENCIES_OUTPUT` and `SUNPRO_DEPENDENCIES` has been removed. If any of those variables are set, ccache now just falls back to running the real compiler.
  [contributed by Joel Rosdahl]

### Bug fixes

- The correct dependency target will now be produced even when a base directory is used — the dependency target will still be an absolute path.
  [contributed by Joel Rosdahl]

- Fixed a bug that could lead to bad modification timestamp (mtime) for object files on systems that lack `utimensat` and `utimes` system calls (such as Windows).
  [contributed by Joel Rosdahl]

- Fixed ordering of MSVC include directory options when using `/external:I<directory>`.
  [contributed by Raihaan Shouhell]

- Fixed capturing of MSVC stdout/stderr when running from Visual Studio.
  [contributed by Orgad Shaneh]

- Carriage return characters are now retained in the compiler output on Windows.
  [contributed by Orgad Shaneh]

- Made sure not to increment the “preprocessed_cache_miss” counter in recache mode.
  [contributed by Joel Rosdahl]

- Fixed an issue with the inode cache in combination with `__DATE__`/`__TIME__`/`__TIMESTAMP__` macros in the source code.
  [contributed by Joel Rosdahl]

- Made sure to enable the inode cache only if subsecond timestamps are available.
  [contributed by Joel Rosdahl]

- Cache entries created with enabled hard linking or file cloning are no longer written to remote storage since they won’t be possible to retrieve correctly anyway.
  [contributed by Joel Rosdahl]

- Ccache now accepts spaces between target and colon when parsing dependency files in the depend mode.
  [contributed by Louis Caron]

- Fixed a crash when failing to write an error message to stderr after failing to write to the log file.
  [contributed by Joel Rosdahl]

- Made ccache able to retrieve an object file from the cache even if the destination object file exists and is read-only.
  [contributed by Joel Rosdahl]

- The `.exe` extension is now stripped from the ccache executable name in `ccache --version` on Windows.
  [contributed by Orgad Shaneh]

- Fixed naming of temporary files written to the cache directory.
  [contributed by Joel Rosdahl]

### Build improvements

- Enabled static runtime linking for MSVC.
  [contributed by Cristian Adam and Rafael Kitover]

- The Zstandard and Hiredis dependencies are now by default downloaded from the Internet when unavailable.
  [contributed by Rafael Kitover]

- Added support for pkgconfig to find a Zstandard installation.
  [contributed by Rosen Penev]

- Removed usage of the deprecated `codecvt` header.
  [contributed by Orgad Shaneh]

- Added headers to CMake project files.
  [contributed by Orgad Shaneh]

### Test improvements

- Made the integration tests work on Windows.
  [contributed by Orgad Shaneh and R. Voggenauer]

- Improved diagnostics from the “Version output readable” test.
  [contributed by Orgad Shaneh]

- Made setting the `KEEP_TESTDIR` variable actually work.
  [contributed by Louis Caron]

- Fixed a typo in depend mode tests.
  [contributed by Louis Caron]

- Added more depend mode tests.
  [contributed by Louis Caron]

### Documentation improvements

- Improved the installation guide.
  [contributed by Rafael Kitover]

- Fixed a typo in the help text.
  [contributed by Joel Rosdahl]

## Ccache 4.6.3

Release date: 2022-08-27

### Bug fixes

- Fixed MSVC support (regression in ccache 4.6.2).
  [contributed by Joel Rosdahl]

- Fixed detection of PCH header for concatenated `-include` option (e.g., `-includepch.h` instead of `-include pch.h`).
  [contributed by Joel Rosdahl]

### Build improvements

- Fixed build with musl when using GCC 12.
  [contributed by Khem Raj]

### Test improvements

- Disabled the “Failure to write output file” test when running on a filesystem that doesn’t support read-only directories.
  [contributed by Joel Rosdahl]

## Ccache 4.6.2

Release date: 2022-08-22

### Bug fixes

- Fixed a race condition that could lead to a crash if a file in the cache is removed with unlucky timing, e.g. by another ccache process doing cache cleanup.
  [contributed by Joel Rosdahl]

- Dependency file rewriting will now always be performed if `base_dir`/`CCACHE_BASEDIR` is active. This fixes a problem with the dependency file content when Clang is used with `-fsanitize=address`.
  [contributed by Joel Rosdahl]

- Fixed handling of error condition for `--hash-file`/`--checksum-file`.
  [contributed by Joel Rosdahl]

- Made sure to enable the inode cache only if subsecond `stat` timestamps are available.
  [contributed by Joel Rosdahl]

- Added a work-around for a Clang bug when writing to a full NFS file system.
  [contributed by Joel Rosdahl]

- Made failure writing to the output file increment the “bad output file” counter instead of “cache miss”.
  [contributed by Joel Rosdahl]

- Fixed false positive cache hits for code constructions similar to `asm(".incbin" " \"file\"")`.
  [contributed by Joel Rosdahl]

- Fixed false success for `-fcolor-diagnostics` probe with GCC. A side effect of this is that a compiler type that ccache can’t identify from the compiler name (such as `/usr/bin/cc` where `cc` is not a symlink) from now on won’t produce color diagnostics when used via ccache even if the compiler actually is GCC or Clang.
  [contributed by Joel Rosdahl]

- More cases of invalid secondary storage URLs are now handled gracefully.
  [contributed by Joel Rosdahl]

- Fixed the display of maximum cache size in `ccache -s` if it’s 0 (= unlimited).
  [contributed by Joel Rosdahl]

- Removed AsciiDoc markup from help text of `--trim-dir`.
  [contributed by Joel Rosdahl]

- The temporary directory is now cleaned up properly even if it’s left unconfigured.
  [contributed by Joel Rosdahl]

- Made cleanup of the temporary directory not rely a directory timestamp.
  [contributed by Joel Rosdahl]

- Made sure to retain mtime/atime when recompressing cache files with `-X`/`--recompress`.
  [contributed by Joel Rosdahl]

- The correct umask is now used when populating the primary cache from a secondary cache.
  [contributed by Joel Rosdahl]

- Fixed creation of temporary files on file systems that don’t support hard links (such as FAT32).
  [contributed by Joel Rosdahl]

- Added knowledge about `-Wa,…​=file` so that ccache then falls back to running the real compiler.
  [contributed by Joel Rosdahl]

- Corrected handling of space in paths when using response file on Windows.
  [contributed by Sergey Semushin]

- Fixed crash due to empty include filename in preprocessor output generated by `f2c`.
  [contributed by Oleg Sidorkin]

### Build improvements

- Fixed build problems with a development version of GCC 13.
  [contributed by Joel Rosdahl]

- Fixed build problems with MSVC.
  [contributed by Florin Trofin]

### Test improvements

- Clang warnings from the “-fdebug-prefix-map” test are now suppressed.
  [contributed by Joel Rosdahl]

- Made sure to only run the “-ftest-coverage + -fprofile-dir” test with GCC.
  [contributed by Joel Rosdahl]

- Fixed printing of error messages with embedded newlines.
  [contributed by Joel Rosdahl]

- Fixed warning when running the “inode_cache” test in isolation.
  [contributed by Joel Rosdahl]

- Fixed test failure when the compiler used for testing is an old ccache version masquerading as the compiler.
  [contributed by Joel Rosdahl]

### Documentation improvements

- Mentioned that mtime is used for LRU cleanup.
  [contributed by Joel Rosdahl]

## Ccache 4.6.1

Release date: 2022-05-15

### New features

- Added support for passing a directory to the MSVC `/Fo` option.
  [contributed by Orgad Shaneh]

- Added knowledge about the `-imsvc` compiler option.
  [contributed by Jacob Young]

- Added knowledge about the `-z` linker option.
  [contributed by Joel Rosdahl]

### Bug fixes

- Improved handling of `.gcno` files in combination with absolute input file paths.
  [contributed by Joel Rosdahl]

- Adapted to changes in GCC 9+ `.gcno` files, which contain the current working directory, by including said directory in the hash. You can opt out of this by enabling “gcno_cwd sloppiness”.
  [contributed by Joel Rosdahl]

- A preexisting object file is no longer considered when using `-fsyntax-only`.
  [contributed by Joel Rosdahl]

- Authenticate with Redis before database selection.
  [contributed by GitHub user 6d5CfLQ3dYAb]

- Don’t exit with an error on failure reading a cached file.
  [contributed by GitHub user 6d5CfLQ3dYAb]

- Bail out on too hard MSVC environment variables `CL` and `_CL_`.
  [contributed by Joel Rosdahl]

- Only use `/run/user/<UID>/ccache-tmp` as the temporary directory if it’s writable.
  [contributed by Joel Rosdahl]

- Fixed handling of the final newline in cached standard output from the compiler.
  [contributed by Orgad Shaneh]

- Fixed a bug related to distcc markers in standard error output.
  [contributed by Joel Rosdahl]

- Paths to `base_dir` are now properly normalized on Windows.
  [contributed by Vili Väinölä and Joel Rosdahl]

- Fixed handling of MSVC `/Fp` and `/Yu` options with concatenated path.
  [contributed by Joel Rosdahl]

- Fixed “Multiple precompiled headers used” error if MSVC `/Yu` option is used after `/Fp`.
  [contributed by Alexey Telishev]

- Check for short reads when reading strings in result/manifest files.
  [contributed by Gregor Jasny]

- Log expanded secondary storage URL in put/remove.
  [contributed by Joel Rosdahl]

- Fixed logging of statistics counters with value higher than one in debug log and stats log.
  [contributed by Joel Rosdahl]

- Avoid incorrect error log message for Redis write operations in `reshare` mode.
  [contributed by Joel Rosdahl]

- Support Redis URL without host (meaning localhost).
  [contributed by Joel Rosdahl]

### Build improvements

- Prefer CMake find module for hiredis and zstd packages.
  [contributed by Cristian Adam and Joel Rosdahl]

- Fixed building and linking BLAKE3 with MSVC.
  [contributed by Rafael Kitover]

- Fixed static linkage with hiredis on Windows.
  [contributed by Orgad Shaneh]

- Fixed miscompile of nonstd::expected on MSVC v19.22.
  [contributed by Jacob Young]

- Fixed build arguments to clang-cl.
  [contributed by Jacob Young]

- Fixed parsing of MSVC response files.
  [contributed by Jacob Young]

- Support Git 1.x when determining ccache version.
  [contributed by Joel Rosdahl]

### Test improvements

- Worked around an endianness problem which affected builds and tests on big-endian systems.
  [contributed by Joel Rosdahl]

- A C++-capable compiler is no longer required for the test suite.
  [contributed by Joel Rosdahl]

- Fixed an issue with inode cache tests, leading to sporadic failures in the inode test suite when running many parallel tests.
  [contributed by Joel Rosdahl]

- Fixed sporadic failures in the profiling test suite.
  [contributed by Jacob Young]

### Documentation improvements

- Added reference to example build configs in installation instructions.
  [contributed by GitHub user vsplesk/]

- Default cache locations are now mentioned for Windows and macOS as well.
  [contributed by Joel Rosdahl]

- Added a warning about usage of `base_dir`.
  [contributed by Joel Rosdahl]

## Ccache 4.6

Release date: 2022-02-27

### New features

- Added support for caching calls to Microsoft Visual C++ (MSVC) and clang-cl (MSVC compatibility for Clang).
  [contributed by Cristian Adam, Luboš Luňák, Orgad Shaneh and Joel Rosdahl]

- Added an option to use a bearer token with the HTTP backend. This makes it possible to use e.g. Google Cloud Storage as a secondary storage backend.
  [contributed by GitHub user Delgan]

- Added support for caching standard output from the compiler.
  [contributed by Luboš Luňák and Joel Rosdahl]

- Added a new `--inspect` option for debugging cache entries, replacing the previous `--dump-manifest` and `--dump-result` options.
  [contributed by Joel Rosdahl]

- Enabled HTTP keep-alive by default.
  [contributed by Joel Rosdahl]

### Bug fixes

- Fixed copying of binary files on Windows.
  [contributed by R. Voggenauer]

- Improved detection of the `.incbin` assembler directive to reduce false positives.
  [contributed by Alexey Sheplyakov]

- Ccache now verifies that `/run/user/<UID>/ccache-tmp` is writable before using it for temporary files.
  [contributed by Joel Rosdahl]

- Fixed statistics output for secondary storage.
  [contributed by Orgad Shaneh]

- Fixed a problem when copying a cache entry from secondary storage into an empty primary storage.
  [contributed by Joel Rosdahl]

- Visual Studio .rsp files with UTF-16LE encoding are now handled correctly.
  [contributed by Vili Väinölä]

- Made conversion to relative paths more reliable on Windows.
  [contributed by Marius Zwicker]

- The process umask is now respected when making hard linked files read only.
  [contributed by Joel Rosdahl]

- A forced recache is no longer considered a “direct cache miss”.
  [contributed by Joel Rosdahl]

### Documentation improvements

- Corrected reference to the `debug_dir` option.
  [contributed by Joel Rosdahl]

- Improved documentation of `--config-path`.
  [contributed by Joel Rosdahl]

- Added documentation that compiler plugins are hashed too.
  [contributed by Philipp Gortan]

### Test improvements

- The “trim_dir” test suite is now only run when cleanup tests are enabled.
  [contributed by Joel Rosdahl]

## Ccache 4.5.1

Release date: 2021-11-17

### Bug fixes

- Fixed entry_size field for result entries. This bug affected the recompression feature (`-X`/`--recompress`) in ccache 4.5.
  [contributed by Joel Rosdahl]

- The actual compression level is now once again stored in the cache entry header.
  [contributed by Joel Rosdahl]

- Corrected error handling for non-constructible secondary storage backends. For instance, this avoids a crash when a Redis server can’t be reached.
  [contributed by Joel Rosdahl]

## Ccache 4.5

Release date: 2021-11-13

### New features

- Made various improvements to the cache entry format. Among other things, the header now contains a creation timestamp and a note of the ccache version used to create the entry. The cache entry checksum has also been upgraded to use 128-bit XXH3 instead 64-bit XXH3.
  [contributed by Joel Rosdahl]

- Added support for cache namespaces. If a namespace configured, e.g. using `CCACHE_NAMESPACE=some_string`, the namespace string will be added to the hashed data for each compilation. This will make the associated cache entries logically separate from cache entries in other namespaces, but they will still share the same storage space. Cache entries can also be selectively removed from the primary cache with the new command line option `--evict-namespace`, potentially in combination with `--evict-older-than`.
  [contributed by Joel Rosdahl]

- Made HTTP keep-alive configurable, defaulting to off for now.
  [contributed by Gregor Jasny]

- Added support for rewriting absolute path to Clang option `--gcc-toolchain`.
  [contributed by Joel Rosdahl]

### Compatibility notes

- A consequence of the changed cache entry format is that ccache 4.5 will not share cache entries with earlier versions. Different ccache versions can however still use the same cache storage without any issues.

### Bug fixes

- Fixed a problem with special characters in the user info part of URLs for HTTP storage.
  [contributed by Russell McClellan]

- Fixed win32 log messages about file locks.
  [contributed by Luboš Luňák]

- Fixed debug directory handling on Windows.
  [contributed by Luboš Luňák]

- The hard link and file clone features are now disabled when secondary storage is used since they only work for the local primary cache.
  [contributed by Joel Rosdahl]

## Ccache 4.4.2

Release date: 2021-09-28

### Bug fixes

- Fixed a bug introduced in 4.4 where ccache could produce false direct cache hits in some situations if it decides to disable the direct mode temporarily (e.g. due to “too new header” file).
  [contributed by Joel Rosdahl]

### Test improvements

- Use shell builtin pwd command for basedir test.
  [contributed by Kira Bruneau]

- Cope with CC being a wrapper script that uses ccache.
  [contributed by Joel Rosdahl]

## Ccache 4.4.1

Release date: 2021-09-11

### New features

- The secondary storage statistics section of `-s/--show-stats` is now shown only if it’s non-empty or with two verbose options.
  [contributed by Joel Rosdahl]

- Added display of statistics counters for misses. Previously they were only implicit in the “hits + misses” sums.
  [contributed by Joel Rosdahl]

### Bug fixes

- Fixed spurious crashes when using the HTTP or Redis backend and the remote connection hung up.
  [contributed by Joel Rosdahl]

- Made sure to always store configuration origin value.
  [contributed by Gregor Jasny]

### Build improvements

- The matching version of lld is now used for Clang.
  [contributed by Gregor Jasny]

- The standard linker is now used if IPO (LTO) is enabled.
  [contributed by Gregor Jasny]

- Disabled IPO (LTO) for MinGW toolchains since they seem to be generally broken.
  [contributed by Gregor Jasny]

- Fixed build errors with Clang on Windows.
  [contributed by Orgad Shaneh]

### Test improvements

- Fixed .incbin test with newer binutil versions.
  [contributed by Joel Rosdahl]

- Fixed basedir test suite failure when using a symlinked CWD.
  [contributed by Joel Rosdahl]

- Improved output of differing text files on failure.
  [contributed by Joel Rosdahl]

## Ccache 4.4

Release date: 2021-08-19

### New features

- Made it possible to share a cache over network or on a local filesystem. The configuration option `secondary_storage`/`CCACHE_SECONDARY_STORAGE` specifies one or several storage backends to query after the primary local cache storage. It is also possible to configure sharding (partitioning) of the cache to spread it over a server cluster using Rendezvous hashing. See the Secondary storage backends chapter in the manual for details.
  [contributed by Joel Rosdahl]

- Added an HTTP backend for secondary storage on any HTTP server that supports GET/PUT/DELETE methods. See How to set up HTTP storage for hints on how to set up an HTTP server for use with ccache.
  [contributed by Gregor Jasny]

- Added a Redis backend for secondary storage on any server that supports the Redis protocol. See How to set up Redis storage for hints on how to set up a Redis server for use with ccache.
  [contributed by Anders F Björklund]

- Added a filesystem backend for secondary storage. It can for instance be used for a shared cache over networked filesystems such as NFS, or for mounting a secondary read-only cache layer into a build container.
  [contributed by Joel Rosdahl]

- Added `--trim-dir`, `--trim-max-size` and `--trim-method` options that can be used to trim a secondary storage directory to a certain size, e.g. via cron.
  [contributed by Joel Rosdahl]

- Added a configuration option `reshare`/`CCACHE_RESHARE` which makes ccache send results to secondary storage even for primary storage cache hits.
  [contributed by Joel Rosdahl]

- Added new statistics counters for direct/preprocessed cache misses, primary storage hits/misses, secondary storage hits/misses/errors/timeouts and forced recaches.
  [contributed by Joel Rosdahl]

- Improved statistics summary. The `-s`/`--show-stats` option now prints a more condensed overview where the counters representing “uncacheable calls” are summed as uncacheable and errors counters. The summary shows hit rate for direct/preprocessed hits/misses, as well as primary/secondary storage hits/misses. More details are shown with `-v`/`--verbose`. Note: Scripts should use `--print-stats` (available since ccache 3.7) instead of trying to parse the output of `--show-stats`.
  [contributed by Joel Rosdahl]

- Added a “stats log” feature (configuration option `stats_log`/`CCACHE_STATSLOG`), which tells ccache to store statistics in a separate log file specified by the user. It can for instance be used to collect statistics for a single build without interference from other concurrent builds. Statistics from the log file can then be viewed with `ccache --show-log-stats`.
  [contributed by Anders F Björklund]

- Added support for clang’s `--config` option.
  [contributed by Tom Stellard]

- Added support for one `-Xarch_*` option that matches a corresponding `-arch` option.
  [contributed by Joel Rosdahl]

- Renamed the `--directory` option to `--dir` for consistency with other options.
  [contributed by Joel Rosdahl]

- Made the `--config-path` and `--dir` options affect the whole command line so that they don’t have to be put before `-s`/`--show-stats`.
  [contributed by Joel Rosdahl]

- Made `--dump-manifest` and `--dump-result` accept filename `-` for reading from standard input.
  [contributed by Anders F Björklund]

- Made the output of `--print-stats` sorted.
  [contributed by Joel Rosdahl]

- Added more internal trace points.
  [contributed by Joel Rosdahl]

### Bug fixes

- Fixed a crash if using `base_dir` and `$PWD` is set to a relative path.
  [contributed by Joel Rosdahl]

- Fixed a bug with `-fprofile-generate` where ccache could give false positive cache hits when compiling with relative paths in another directory.
  [contributed by Joel Rosdahl]

- Fixed a bug in `debug_dir`/`CCACHE_DEBUGDIR`. The absolute path to the object file was not created correctly if the object file didn’t already exist.
  [contributed by Joel Rosdahl]

- Disabled preprocessor hits for pre-compiled headers with Clang again.
  [contributed by Arne Hasselbring]

- Fixed a problem when using the Gold linker on MIPS by only probing for a faster linker in dev build mode and on x86_64.
  [contributed by Joel Rosdahl]

- Made the `-DENABLE_TRACING=1` mode work again.
  [contributed by Anders F Björklund]

### Changed tooling

- A C++14 compiler or newer is now required to build ccache. For GCC, this means version 6 or newer in practice.

- CMake 3.10 or newer is now required to build ccache.

- Asciidoctor is now required to build ccache documentation.

### Build/test/documentation improvements

- Fixed an issue in the modules test suite that showed up when running the ccache test suite with the clang wrapper provided by Nixpkgs.
  [contributed by Ryan Burns]

- Made the nvcc_ldir test suite require a working NVCC.
  [contributed by Michael Kruse]

- Made the ivfsoverlay test suite more robust.
  [contributed by Michael Kruse]

- Fixed issue with usage of `/FI` when building ccache with MSVC.
  [contributed by Michael Kruse]

- Fixed Apple Clang detection in the integration test suite.
  [contributed by Gregor Jasny]

- Made clang the default compiler when running the test suite on macOS.
  [contributed by Gregor Jasny]

- Silenced stray printout from "-P -c" test case.
  [contributed by Joel Rosdahl]

- Fixed selection of the ccache binary to use when running the test suite with multi-config generators like Xcode.
  [contributed by Gregor Jasny]

- Fixed CMake feature detection for `ctim`/`mtim` fields in `struct stat`.
  [contributed by Gregor Jasny]

- Fixed issue with not linking to .lib correctly on Windows.
  [contributed by R. Voggenauer]

- Made it possible to override `CCACHE_DEV_MODE` on the command line.
  [contributed by Joel Rosdahl]

- Improved HTML documentation style.
  [contributed by Joel Rosdahl with minor fixes by Orgad Shaneh]

## Ccache 4.3

Release date: 2021-05-09

### New features

- Ccache now ignores the Clang compiler option `-ivfsoverlay` and its argument if you opt in to “ivfsoverlay sloppiness”. This is useful if you use Xcode, which uses a virtual file system (VFS) for things like combining Objective-C and Swift code.

- When using `-P` in combination with `-E`, ccache now reports this as “called for preprocessing” instead of “unsupported compiler option”.

- Added support for `-specs file.specs` and `--specs file.specs` without an equal sign between the arguments.

### Bug fixes

- “Split dwarf” code paths are now disabled when outputting to `/dev/null`. This avoids an attempt to delete `/dev/null.dwo`.

- Made the `stat`/`lstat` wrapper function for Windows treat pending deletes as missing files.

- Fixed a bug that made ccache process header files redundantly for some relative headers when using Clang.

- The object path is now included in the input hash when using `-fprofile-arcs` (or `--coverage`) since the object file embeds a `.gcda` path based on the object file path.

### Build improvements

- Added an `ENABLE_DOCUMENTATION` build option (default: true) that can be used to disable the build of documentation.

- Fixed detection of pthread features.

- Quote CMake variables expansions to avoid errors when `${CMAKE_C_FLAGS_RELWITHDEBINFO}` or `${CMAKE_CXX_FLAGS_RELWITHDEBINFO}` expands to the empty string.

## Ccache 4.2.1

Release date: 2021-03-27

### Bug fixes

- Ccache now only duplicates the stderr file descriptor into `$UNCACHED_ERR_FD` for calls to the preprocessor/compiler. This works around a complex bug in interaction with GNU Make, LTO linking and the Linux PTY driver.

- Fixed detection of color diagnostics usage when using `-Xclang -fcolor-diagnostics` options.

- The `-frecord-gcc-switches` compiler option is now handled correctly to avoid false positive cache hits.

- Made it possible for per-compilation debug log files to be written in most argument processing error scenarios. Previously, ccache would only write debug log files if the argument processing phase was successful.

- Made ccache bail out on too hard Clang option `-gen-cdb-fragment-path`.

- The `run_second_cpp` made is now enforced on macOS if `-g` is used since newer Clang versions on macOS produce different debug information when compiling preprocessed code.

- Made ccache only reject `-f(no-)color-diagnostics` for a known GCC compiler. This fixes a problem when using said option with Clang on macOS.

- Implemented a better `stat`/`lstat` wrapper function for Windows.

- Fixed a bug where ccache could return stale cache results on Windows.

- Fixed handling of long command lines on Windows.

### Portability and build improvements

- Build configuration scripts now probe for atomic increment as well. This fixes a linking error on Sparc.

- An existing CMake log message level is now used when warning about not finding asciidoc.

- Added support for building ccache with xlclang++ on AIX 7.2.

- Fixed assertion in the “Debug option” test.

- Made build configuration skip using ccache when building with MSVC.

- Upgraded to doctest 2.4.6. This fixes a build error with glibc >= 2.34.

### Documentation

- Fixed markup of `compiler_type` value `other`.

- Fixed markup of `debug_dir` documentation.

- Fixed references to the `extra_files_to_hash` configuration option.

## Ccache 4.2

Release date: 2021-02-02

### 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.

## Ccache 4.1

Release date: 2020-11-22

### New features

- Symlinks are now followed when guessing the compiler. This makes ccache able to guess compiler type “GCC” for a common symlink chain like this: `/usr/bin/cc` → `/etc/alternatives/cc` → `/usr/bin/gcc` → `gcc-9` → `x86_64-linux-gnu-gcc-9`.

- Added a new `compiler_type` (`CCACHE_COMPILERTYPE`) configuration option that allows for overriding the guessed compiler type.

- Added support for caching compilations with `-fsyntax-only`.

- Added a command line option `--config-path`, which specifies the configuration file to operate on. It can be used instead of setting `CCACHE_CONFIGPATH` temporarily.

### Bug fixes

- The original color diagnostics options are now retained when forcing colored output. This fixes a bug where feature detection of the `-fcolor-diagnostics` option would succeed when run via ccache even though the actual compiler doesn’t support it (e.g. GCC <4.9).

- Fixed a bug related to umask when using the `umask` (`CCACHE_UMASK`) configuration option.

- Allow `ccache ccache compiler …​` (repeated `ccache`) again.

- Fixed parsing of dependency file in the “depend mode” so that filenames with space or other special characters are handled correctly.

- Fixed rewriting of the dependency file content when the object filename includes space or other special characters.

- Fixed runtime detection of AVX2 support, not relying on the sometimes broken `__builtin_cpu_support` routine.

- Added missing parameters to a log call, thus avoiding a crash when it is found out at runtime that file cloning is unsupported by the OS.

### Portability and build fixes

- The ccache binary is now linked with `libatomic` if needed. This fixes build problems with GCC on ARM and PowerPC.

- Fixed build of BLAKE3 code with Clang 3.4 and 3.5.

- Fixed “use of undeclared identifier 'CLONE_NOOWNERCOPY'” build error on macOS 10.12.

- Fixed build problems related to missing AVX2 and AVX512 support on older macOS versions.

- Fixed static linkage with libgcc and libstdc++ for MinGW and made it optional.

- Fixed conditional compilation of “robust mutex” code for the inode cache routines.

- Fixed badly named man page filename (`Ccache.1` instead of `ccache.1`).

- Disabled some tests on ancient Clang versions.

### Other improvements and fixes

- The man page is now built by default if the required tools are available.

- Use CMake `A2X_EXE` variable instead of hardcoded `a2x`.

- Improved build errors when building ccache with very old compiler versions.

- Fall back to version “unknown” when Git is not installed.

- Documented the relationship between `CCACHE_DIR` and `-d/--directory`.

- Fixed incorrect reference and bad markup in the manual.

## Ccache 4.0

Release date: 2020-10-18

### Summary of major changes

- Changed the default cache directory location to follow the XDG base directory specification.

- Changed compression algorithm from Deflate (zlib) to Zstandard, enabled by default.

- Added functionality for recompressing cache content with a higher compression level.

- Changed hash algorithm from MD4 to BLAKE3.

- Added checksumming with XXH3 to detect data corruption.

- Improved cache directory structure.

- Added support for using file cloning (AKA “reflinks”).

- Added an experimental “inode cache” for file hashes.

### Compatibility notes

- The default location of the cache directory has changed to follow the XDG base directory specification (more details below). This means that scripts can no longer assume that the cache directory is `~/.ccache` by default. The `CCACHE_DIR` environment variable still overrides the default location just like before.

- The cache directory structure has changed compared to previous versions (more details below). This means that ccache 4.0 will not share cache results with earlier versions. It is however safe to run ccache 4.0 and earlier versions against the same cache directory: cache bookkeeping, statistics and cleanup are backward compatible, with the minor exception that some statistics counters incremented by ccache 4.0 won’t be visible when running `ccache -s` with an older version.

### Changed tooling

- CMake is now used instead of Autoconf for configuration and building.

- A C++11 compiler, a C99 compiler and CMake 3.4.3 or newer are now required to build ccache.

- Ccache can now be built using Microsoft Visual C++.

### Detailed functional changes

- All data of a cached result is now stored in a single file called “result” instead of up to seven files. This reduces inode usage and improves data locality.

- Added compression of result and manifest files using the Zstandard algorithm. Compression is enabled by default with compression level 1. This makes ccache able to store more data in the cache. Previously compression using Deflate (zlib) was available but disabled by default. Files can be recompressed with another compression level later with the `-X/--recompress` option described further below.

- Changed from MD4 to BLAKE3 for hashing input. This improves performance and reduces the risk of hash collisions.

- Added checksumming of result and manifest files using the XXH3 algorithm to detect data corruption.

- Ccache now follows the XDG base directory specification. This means that the default cache directory on Unix systems is `$XDG_CACHE_HOME/ccache` (with `~/.cache/ccache` as the fallback if `XDG_CACHE_HOME` is not set) and the configuration file is `$XDG_CONFIG_HOME/ccache/ccache.conf` (with `~/.config/ccache/ccache.conf` as the fallback). On macOS, the fallbacks are `~/Library/Caches/ccache` and `~/Library/Preferences/ccache/ccache.conf`. On Windows, the fallbacks are `%APPDATA%/ccache` and `%APPDATA%/ccache/ccache.conf`. Exception: If the legacy `~/.ccache` directory exists, that directory is used as the default cache location and the configuration file is `~/.ccache/ccache.conf`.

- Cache statistics are now stored in files on cache level 2 to reduce lock contention when there are many parallel compilations.

- An appropriate cache directory level structure is now chosen automatically. The `cache_dir_levels` (`CCACHE_NLEVELS`) configuration option has therefore been removed.

- Added an experimental “inode cache” for file hashes, allowing computed hash values to be reused both within and between builds. The inode cache is off by default but can be enabled by setting `inode_cache` (`CCACHE_INODECACHE`) to `true`.

- Added support for using file cloning (AKA “reflinks”) on Btrfs, XFS and APFS to copy data to and from the cache very efficiently.

- Two measures have been implemented to make the hard link mode safer: hard-linked files are made read-only and inadvertent content changes that affect file size are detected.

- Added a command line option `-x/--show-compression` which shows statistics about cache compression.

- Added a command line option `-X/--recompress` which recompresses the cache data with another compression level or makes it uncompressed. If you choose to disable compression by default, or choose to use a compression level with a low compression ratio, you can recompress the cache with a higher compression level after the build or at another time when there are more CPU cycles available, for instance every night. Only files that are currently compressed with a different level than the wanted level will be recompressed.

- Added a command line option `--evict-older-than` which removes cache entries older than a certain age.

- Added a command line option `-d/--directory` which specifies a cache directory to operate on. It can be used instead of setting `CCACHE_DIR` temporarily.

- A progress bar has been added to show the progress of time-consuming options like `-c/--cleanup`, `-C/--clear`, `--evict-older-than`, `-x/--show-compression` and `-X/--recompress`.

- When supported by the CPU, a SIMD-friendly (using AVX2) algorithm is now used to scan input source code for `__DATE__`, `__TIME__` and `__TIMESTAMP__` macros. This can decrease the number of CPU cycles for a direct cache hit with up to 15% in some cases.

- Some unnecessary `stat(2)` system calls are now avoided when verifying header files.

- Compiler diagnostic messages are now always cached in color. Ccache then strips the color codes on the fly when requested explicitly by a command line option or when stderr does not refer to a TTY. This allows IDEs and terminals to share cached compilation results.

- The configuration option `compiler` (`CCACHE_COMPILER`) now always takes effect if specified. Previously, the configuration option was only used when the compiler specified on the command line was looked up via `PATH` (i.e., not when an absolute path was specified).

- Added optional logging to syslog if `log_file` (`CCACHE_LOGFILE`) is set to `syslog`.

- The compiler option `-fmodules` is now handled in the “depend mode”. If “depend mode” is disabled the option is still considered too hard and ccache will fall back to running the compiler.

- Ccache can now cache compilations with coverage notes (`.gcno` files) produced by GCC 9+ in combination with `-fprofile-dir=dir`.

- `realpath(3)` is no longer used for normalization when computing relative paths. This makes it possible to get cache hits when the source or build directory is a symbolic link to an absolute path that includes unstable information like build IDs or timestamps.

- Added an `ignore_options` (`CCACHE_IGNOREOPTIONS`) configuration option which makes it possible to exclude compiler options from the hash.

- Added an `absolute_paths_in_stderr` (`CCACHE_ABSSTDERR`) configuration option which makes ccache rewrite absolute paths in compiler warnings and errors to relative.

- Improved handling of umask. The configured `umask` (`CCACHE_UMASK`) is now only applied to files and directories in the cache directory. Previously the umask was applied to all files produced by ccache and the executed compiler.

- Ccache is now able to share cache entries for different object file names when using `-MD` or `-MMD`.

- Clang’s `-Xclang` (used by CMake for precompiled headers), `-fno-pch-timestamp`, `-emit-pch`, `-emit-pth` and `-include-pth` options are now understood.

- Added support for the HIP (“C++ Heterogeneous-Compute Interface for Portability”) language.

- The manifest format now allows for header files larger than 4 GiB.

- Made it possible to once again cache compilations with `__DATE__` in the source code.

- Added handling of the `__TIMESTAMP__` macro.

- An absolute input source path is now rewritten to a relative path when using `base_dir`.

- `waitpid` system calls interrupted by a signal are now handled correctly.

- Made handling of `.dwo` files and interaction between `-gsplit-dwarf` and other `-g*` options more robust.

- The “couldn’t find compiler” statistics counter is no longer incremented when ccache exits with a fatal error.

- Failure to run a `compiler_check` command is no longer a fatal error.

- Added command line options `--dump-result` and `--extract-result` for inspecting and extracting result files.

- Added a command line option `--checksum-file` for debugging or evaluating the checksum algorithm.

- Improved error message for `ccache -o=K=V` (trying to set a configuration option named `=K`).

- Made timestamps in statistics files Y2038-proof.

- Removed code for populating a newly created configuration file with max cache size and max files values for cache directories created by ccache versions older than 3.2 (released 2014).

- Removed knowledge about a top-level `stats` file created by ccache versions older than 3.1 (released 2010).

### Other improvements

- Improved help text and documentation of command line options.

- Improved documentation of the `base_dir` configuration option.

- Improved documentation of preprocessor and direct modes.

- Added HTML anchors to configuration options in the manual so that it is possible link to a specific option.

- Tweaked placement of “(readonly)” in output of `ccache -s`.

- Improved visibility of color output from the test suite.

- Fixed a problem when running the test suite with Clang without a libgcov library available.

- Fixed test suite problems on macOS.

- Disabled hardlink tests on AFS since it lacks such support.

- Disabled read-only tests on file systems that lack such support.

## Ccache 3.7.12

Release date: 2020-10-01

### Bug fixes

- Coverage files (`.gcno`) produced by GCC 9+ when using `-fprofile-dir=dir` are now handled gracefully by falling back to running the compiler.

- Fixed writing to log file larger than 2 GiB when running ccache compiled in 32-bit mode.

### Other

- Improved documentation about sharing a cache on NFS.

- Fixed test case failures with old objdump versions.

- Fixed test case failures with GCC 4.4.

## Ccache 3.7.11

Release date: 2020-07-21

### Bug fixes

- Added knowledge about `-fprofile-{correction,reorder-functions,values}`.

- ccache now handles the Intel compiler option `-xCODE` (where `CODE` is a processor feature code) correctly.

- Added support for NVCC’s `-Werror` and `--Werror` options.

### Other

- ccache’s “Directory is not hashed if using -gz[=zlib]” tests are now skipped for GCC 6.

## Ccache 3.7.10

Release date: 2020-06-22

### Bug fixes

- Improved handling of profiling options. ccache should now work correctly for profiling options like `-fprofile-{generate,use}[=path]` for GCC ≥ 9 and Clang as well as `-fauto-profile[=path]` and the Clang-specific `-fprofile-instr-{generate,use}[=path]` and `-fprofile-sample-{use,accurate}` options.

- ccache now copies files directly from the cache to the destination file instead of via a temporary file. This avoids problems when using filenames long enough to be near the file system’s filename max limit.

- When the hard-link mode is enabled, ccache now only uses hard links for object files, not other files like dependency files. This is because compilers unlink object files before writing to them but they don’t do that for dependency files, so the latter can become overwritten and therefore corrupted in the cache.

- Fixed a glitch related to hard-link mode and an empty cache.

- ccache now supports the ccache.conf file to be a symlink.

- Temporary files are now deleted immediately on signals like SIGTERM and SIGINT instead of some time later in a cleanup phase.

- Fixed a bug that affected ccache’s `-o/--set-config` option for the `base_dir` and `cache_dir_levels` keys.

## Ccache 3.7.9

Release date: 2020-03-29

### Bug fixes

- Fixed replacing of /dev/null when building as root with hard link mode enabled and using `-o /dev/null`.

- Removed incorrect assertion resulting in “ccache: error: Internal error in format” when using `-fdebug-prefix-map=X=` with X equal to `$PWD`.

### Other

- Improved CUDA/NVCC support: Recognize `-dc` and `-x cu` options.

- Improved name of temporary file used in NFS-safe unlink.

## Ccache 3.7.8

Release date: 2020-03-16

### Bug fixes

- Use `$PWD` instead of the real CWD (current working directory) when checking for CWD in preprocessed output. This fixes a problem when `$PWD` includes a symlink part and the user has set `hash_dir = false`.

- Rewrote the Windows version of the lockfile routines. This should mitigate several problems with the old implementation.

- If `localtime_r` fails the epoch time is now logged instead of garbage.

### Other

- Improved error message when a boolean environment variable has an invalid value.

- Improved the regression fix in ccache 3.7.5 related to not passing compilation-only options to the preprocessor.

- ccache’s PCH test suite now skips running the tests if it detects broken PCH compiler support.

- Fixed unit test failure on Windows.

- Fixed “stringop-truncation” build warning on Windows.

- Improved “x_rename” implementation on Windows.

- Improved removal of temporary file when rewriting absolute paths to relative in the dependency file.

- Clarified “include_file_ctime sloppiness” in the Performance section in the manual.

## Ccache 3.7.7

Release date: 2020-01-05

### Bug fixes

- Fixed a bug related to object file location in the dependency file (if using `-MD` or `-MMD` but not `-MF` and the build directory is not the same as the source directory then the object file location in the `.d` file would become incorrect). This fixes regression in ccache 3.7.5 introduced by the bug fix related to EDG-based compilers. Note that this removes support for EDG-based compilers again. (A better fix for this is planned for ccache 4.0.)

- Removed the unify mode since it has bugs and shortcomings that are non-trivial or impossible to fix: it doesn’t work with the direct mode, it doesn’t handle C++ raw strings correctly, it can give false cache hits for `.incbin` directives, it’s turned off when using `-g` and it can make line numbers in warning messages and `LINE` macros incorrect.

- mtime and ctime values are now stored in the manifest files only when sloppy_file_stat is set. This avoids adding superfluous manifest file entries on direct mode cache misses.

- A “Result:” line is now always printed to the log.

- The “cache miss” statistics counter will now be updated for read-only cache misses, making it consistent with the cache hit case.

## Ccache 3.7.6

Release date: 2019-11-17

### Bug fixes

- The opt-in “file_macro sloppiness” mode has been removed so that the input file path now is always included in the direct mode hash. This fixes a bug that could result in false cache hits in an edge case when “file_macro sloppiness” is enabled and several identical source files include a relative header file with the same name but in different directories.

- Statistics files are no longer lost when the filesystem of the cache is full.

- Bail out on too hard Clang option `-MJarg` (in addition to the previous bailout of `-MJ arg`).

- Properly handle color diagnostics in the depend mode as well.

## Ccache 3.7.5

Release date: 2019-10-22

### New features

- Added support for `-MF=arg` (with an extra equal sign) as understood by EDG-based compilers.

### Bug fixes

- Fixed a regression in 3.7.2 that could result in a warning message instead of an error in an edge case related to usage of “-Werror”.

- An implicit `-MQ` is now passed to the preprocessor only if the object file extension is non-standard. This will make it easier to use EDG-based compilers (e.g. GHS) which don’t understand `-MQ`. (This is a bug fix of the corresponding improvement implemented in ccache 3.4.)

- ccache now falls back to running the real compiler instead of failing fataly if an internal temporary file is missing after compilation.

- Fixed a crash if localtime returns null pointer in localtime_r replacement.

- Fixed header file dependency tracking when building ccache itself.

- Fixed warning during configure in out-of-tree build in developer mode.

## Ccache 3.7.4

Release date: 2019-09-12

### Improvements

- Added support for the `-gz[=type]` compiler option (previously ccache would think that “-gz” alone would enable debug information, thus potentially including the current directory in the hash).

- Added support for converting paths like “/c/users/…​” into relative paths on Windows.

## Ccache 3.7.3

Release date: 2019-08-17

### Bug fixes

- The cache size (which is counted in “used disk blocks”) is now correct on filesystems that use more or less disk blocks than conventional filesystems, e.g. ecryptfs or btrfs/zfs with transparent compression. This also fixes a related problem with ccache’s own test suite when run on such file systems.

- Fixed a regression in 3.7.2 when using the compiler option “-Werror” and then “-Wno-error” later on the command line.

## Ccache 3.7.2

Release date: 2019-07-19

### Bug fixes

- The compiler option `-gdwarf*` no longer forces “run_second_cpp = true”.

- Added verification that the value passed to the `-o/--set-config` option is valid.

- Fixed detection of precompiled headers in the depend mode.

- Bail out on too hard Clang option `-ftime-trace`.

- ccache now updates the correct stats file when adding/updating manifest files. This bug previously made the file and size statistics counters incorrect over time.

- Fixed warnings from Clang about unused arguments during preprocessing.

- Unknown manifest versions are now handled gracefully in `--dump-manifest`.

- Fixed `make check` with “funny” locales.

### Documentation

- Added a hint about not running `autogen.sh` when building from a release archive.

- Mention that `xsltproc` is needed when building from the source repository.

## Ccache 3.7.1

Release date: 2019-05-01

### Changes

- Fixed a problem when using the compiler option `-MF /dev/null`.

- Long commandlines are now handled gracefully on Windows by using the `@file` syntax to avoid hitting the commandline size limit.

- Fixed complaint from GCC 9’s `-Werror=format-overflow` when compiling ccache itself.

## Ccache 3.7

Release date: 2019-04-23

### Changes

- Fixed crash when the debug mode is enabled and the output file is in a non-writable directory, e.g. when the output file is `/dev/null`.

- Fixed an issue when printing very large log messages to the debug log.

- Fixed bugs related to support for `-gsplit-dwarf`. Previously ccache could produce an incorrect link to the `.dwo` file in the `.o` file.

- Compilations with /dev/null as the input file are now cached.

- ccache has learned how to construct the object filename if no `-o` option is given and the source filename does not include a `.` or ends with a `.`.

- Fixed a temporary file leak when the depend mode is enabled and the compiler produces standard error output.

- Fixed a bug in the depend mode where a manifest hash only could be associated with one set of header dependencies.

- Manifest files did not get marked as used on direct cache hits, so the LRU cache cleanup would incorrectly remove them eventually. This has been fixed.

- The rewriting of absolute paths into relative paths in the dependency file has been enabled in the depend mode as well.

- ccache now ignores unknown keys in configuration files for forward compatibility.

- Rearranged command-line options into sections in the help text.

- Documented the previously undocumented `--dump-manifest` and `--hash-file` options (only useful for debugging ccache itself).

- Added missing documentation for the command-line option `-k/--get-config` added in ccache 3.5.

- Renamed the `--print-config` command to `--show-config`.

- Added a new `--print-stats` command that prints statistics counters in machine-parsable (tab-separated) format.

- ccache no longer creates a missing output directory, thus mimicking the compiler behavior for `-o out/obj.o` when `out` doesn’t exist.

- `-fdebug-prefix-map=ARG`, `-ffile-prefix-map=ARG` and `-fmacro-prefix-map=ARG` are now included in the hash, but only the part before “ARG”. This fixes a bug where compiler feature detection of said flags would not work correctly with ccache.

- Bail out on too hard compiler option `-gtoggle`.

- Bail out on too hard Clang options `--analyze` and `-analyze`.

- Improved debug logging of file hashes in depend mode.

- Improved handling of various `-g*` options. In particular, ccache now understands that `-g0` cancels out previous `-g* options`.

- Worked around a problem with Automake related to `.d` files when using the hard link mode.

- Added opt-in (at configure time) support for enabling trace logs for profiling ccache itself. See `doc/DEVELOPER.md` in the code tree for more information

- Removed support for Fortran 77 again. Some Fortran support was added in ccache 3.3, but the implementation did not work when Fortran modules are involved.

## Ccache 3.6

Release date: 2019-01-14

### Changes

- ccache now has an opt-in “depend mode”. When enabled, ccache never executes the preprocessor, which results in much lower cache miss overhead at the expense of a lower potential cache hit rate. The depend mode is only possible to use when the compiler option `-MD` or `-MMD` is used.

- Added support for GCC’s `-ffile-prefix-map` option. The `-fmacro-prefix-map` option is now also skipped from the hash.

- Added support for multiple `-fsanitize-blacklist` arguments.

- ccache now includes the environment variables `LANG`, `LC_ALL`, `LC_CTYPE` and `LC_MESSAGES` in the hash since they may affect localization of compiler warning messages. Set sloppiness to `locale` to opt out of this.

- Fixed a problem due to Clang overwriting the output file when compiling an assembler file.

- Clarified the manual to explain the reasoning behind the “file_macro” sloppiness setting in a better way.

- ccache now handles several levels of nonexistent directories when rewriting absolute paths to relative.

- A new sloppiness setting `clang_index_store` makes ccache skip the Clang compiler option `-index-store-path` and its argument when computing the manifest hash. This is useful if you use Xcode, which uses an index store path derived from the local project path. Note that the index store won’t be updated correctly on cache hits if you enable this option.

- Rename sloppiness `no_system_headers` to `system_headers` for consistency with other options. `no_system_headers` can still be used as an (undocumented) alias.

- The GCC variables “DEPENDENCIES_OUTPUT” and “SUNPRO_DEPENDENCIES” are now supported correctly.

- The algorithm that scans for `_DATE` and `__TIME__` tokens in the hashed source code now doesn’t produce false positives for tokens where `__DATE__` or `__TIME__` is a substring.

## Ccache 3.5.1

Release date: 2019-01-02

### Changes

- Added missing getopt_long.c source file to release archive.

- Fixed (harmless) compiler warnings when building ccache object files.

- CFLAGS is no longer passed to the linker when linking ccache.

- Improved development mode build flags.

## Ccache 3.5

Release date: 2018-10-15

### Changes

- Added a boolean `debug` (`CCACHE_DEBUG`) configuration option. When enabled, ccache will create per-object debug files that are helpful e.g. when debugging unexpected cache misses. See also the new “Cache debugging” section in the manual.

- Renamed `CCACHE_CC` to `CCACHE_COMPILER` (keeping the former as a deprecated alias).

- Added a new command-line option `-k/--get-config` that prints the value of a config key.

- It is now possible to let ccache hash a precomputed checksum file instead of the full content of a precompiled header. This can save time for large precompiled headers. Note that the build system needs to keep the checksum file in sync with the precompiled header for this to work.

- Improved performance substantially when using `hash_dir = false` on platforms like macOS where `getcwd()` is slow.

- Added “stats updated” timestamp in `ccache -s` output. This can be useful if you wonder whether ccache actually was used for your last build.

- Renamed “stats zero time” to “stats zeroed” and documented it. The counter is also now only present in `ccache -s` output when `ccache -z` actually has been called.

- The content of the `-fsanitize-blacklist` file is now included in the hash, so updates to the file will now correctly result in separate cache entries.

- It’s now possible to opt out of building and installing man pages when running `make install` in the source repository.

- If the compiler type can’t be detected (e.g. if it is named `cc`), use safer defaults that won’t trip up Clang.

- Made the ccache test suite work on FreeBSD.

- Added `file_stat_matches_ctime` option to disable ctime check if `file_stat_matches` is enabled.

- Made “./configure --without-bundled-zlib” do what’s intended.

## Ccache 3.4.3

Release date: 2018-09-02

### Bug fixes

- Fixed a race condition when creating the initial config file in the cache directory.

- Bail out on too hard Clang option `-MJ`.

- Bail out on too hard option `-save-temps=obj`.

- Handle separate parameter to Clang option `-target` correctly.

- Upgraded bundled zlib to version 1.2.11.

## Ccache 3.4.2

Release date: 2018-03-25

### Bug fixes

- The cleanup algorithm has been fixed to not misbehave when files are removed by another process while the cleanup process is running. Previously, too many files could be removed from the cache if multiple cleanup processes were triggered at the same time, in extreme cases trimming the cache to a much smaller size than the configured limits.

- Correctly hash preprocessed headers located in a “.gch directory”. Previously, ccache would not pick up changes to such precompiled headers, risking false positive cache hits.

- Fixed build failure when using the bundled zlib sources.

- ccache 3.3.5 added a workaround for not triggering Clang errors when a precompiled header’s dependency has an updated timestamp (but identical content). That workaround is now only applied when the compiler is Clang.

- Made it possible to perform out-of-source builds in dev mode again.

## Ccache 3.4.1

Release date: 2018-02-11

### Bug fixes

- Fixed printing of version number in `ccache --version`.

## Ccache 3.4

Release date: 2018-02-11

### New features and enhancements

- The compiler option form `--sysroot arg` is now handled like the documented `--sysroot=arg` form.

- Added support for caching `.su` files generated by GCC flag `-fstack-usage`.

- ccache should now work with distcc’s “pump” wrapper.

- The optional unifier is no longer disabled when the direct mode is enabled.

- Added support for NVCC compiler options `--compiler-bindir/-ccbin`, `--output-directory/-odir` and `--libdevice-directory/-ldir`.

- Boolean environment variable settings no longer accept the following (case-insensitive) values: `0`, `false`, `disable` and `no`. All other values are accepted and taken to mean “true”. This is to stop users from setting e.g. `CCACHE_DISABLE=0` and then expect the cache to be used.

- Improved support for `run_second_cpp = false`: If combined with passing `-fdirectives-only` (GCC) or `frewrite-includes` (Clang) to the compiler, diagnostics warnings and similar will be correct.

- An implicit `-MQ` is now passed to the preprocessor only if the object file extension is non-standard. This should make it easier to use EDG-based compilers (e.g. GHS) which don’t understand `-MQ`.

- ccache now treats an unreadable configuration file just like a missing configuration file.

- Documented more pitfalls with enabling `hard_link` (`CCACHE_HARDLINK`).

- Documented caveats related to colored warnings from compilers.

### Bug fixes

- File size and number counters are now updated correctly when files are overwritten in the cache, e.g. when using `CCACHE_RECACHE`.

- `run_second_cpp` is now forced for NVCC.

- Fixed how the NVCC options `-optf` and `-odir` are handled.

## Ccache 3.3.6

Release date: 2018-01-28

### New features and enhancements

- Improved instructions on how to get cache hits between different working directories.

### Bug fixes

- Fixed regression in ccache 3.3.5 related to the `UNCACHED_ERR_FD` feature.

## Ccache 3.3.5

Release date: 2018-01-13

### New features and enhancements

- Documented how automatic cache cleanup works.

### Bug fixes

- Fixed a regression where the original order of debug options could be lost. This reverts the “Improved parsing of `-g*` options” feature in ccache 3.3.

- Multiple `-fdebug-prefix-map` options should now be handled correctly.

- Fixed matching of directories in the `ignore_headers_in_manifest` configuration option.

- Fixed detection of missing argument to `-opt`/`--options-file`.

- ccache now bails out when building a precompiled header if any of the corresponding header files has an updated timestamp. This fixes complaints from Clang.

- Fixed a bug related to erroneously storing a dependency file with absolute paths in the cache on a preprocessed hit.

- `ccache -c/--cleanup` now works like documented: it just recalculates size counters and trims the cache to not exceed the max size and file number limits. Previously, the forced cleanup took “limit_multiple” into account, so that `ccache -c/--cleanup` by default would trim the cache to 80% of the max limit.

- ccache no longer ignores linker arguments for Clang since Clang warns about them.

- Plugged a couple of file descriptor leaks.

- Fixed a bug where ccache would skip hashing the compiler argument following a `-fno-working-directory`, `-fworking-directory`, `-nostdinc`, `-nostdinc++`, `-remap` or `-trigraphs` option in preprocessor mode.

## Ccache 3.3.4

Release date: 2017-02-17

### New features and enhancements

- Documented the different cache statistics counters.

### Bug fixes

- Fixed a regression in ccache 3.3 related to potentially bad content of dependency files when compiling identical source code but with different source paths. This was only partially fixed in 3.3.2 and reverts the new “Names of included files are no longer included in the hash of the compiler’s preprocessed output” feature in 3.3.

- Corrected statistics counter for `-optf`/`--options-file` failure.

- Fixed undefined behavior warnings in ccache found by `-fsanitize=undefined`.

## Ccache 3.3.3

Release date: 2016-10-26

### Bug fixes

- ccache now detects usage of `.incbin` assembler directives in the source code and avoids caching such compilations.

## Ccache 3.3.2

Release date: 2016-09-28

### Bug fixes

- Fixed a regression in ccache 3.3 related to potentially bad content of dependency files when compiling identical source code but with different source paths.

- Fixed a regression in ccache 3.3.1: ccache could get confused when using the compiler option `-Wp,` to pass multiple options to the preprocessor, resulting in missing dependency files from direct mode cache hits.

## Ccache 3.3.1

Release date: 2016-09-07

### Bug fixes

- Fixed a problem in the “multiple `-arch` options” support introduced in 3.3. When using the direct mode (the default), different combinations of `-arch` options were not detected properly.

- Fixed an issue when compiler option `-Wp,-MT,path` is used instead of `-MT path` (and similar for `-MF`, `-MP` and `-MQ`) and `run_second_cpp` (`CCACHE_CPP2`) is enabled.

## Ccache 3.3

Release date: 2016-08-27

### Notes

- A C99-compatible compiler is now required to build ccache.

### New features and enhancements

- The configuration option `run_second_cpp` (`CCACHE_CPP2`) now defaults to true. This improves ccache’s out-of-the-box experience for compilers that can’t compile their own preprocessed output with the same outcome as if they compiled the real source code directly, e.g. newer versions of GCC and Clang.

- The configuration option `hash_dir` (`CCACHE_HASHDIR`) now defaults to true.

- Added a new `ignore_headers_in_manifest` configuration option, which specifies headers that should be ignored in the direct mode.

- Added a new `prefix_command_cpp` (`CCACHE_PREFIX_CPP`) configuration option, which specifies one or several prefixes to add to the command line ccache uses when invoking the preprocessor.

- Added a new `limit_multiple` (`CCACHE_LIMIT_MULTIPLE`) configuration option, which specifies how much of the cache to remove when cleaning.

- Added a new `keep_comments_cpp` (`CCACHE_COMMENTS`) configuration option, which tells ccache not to discard the comments before hashing preprocessor output. This can be used to check documentation with `-Wdocumentation`.

- Added a new sloppiness option `no_system_headers`, which tells ccache not to include system headers in manifest files.

- Added a new statistics counter that tracks the number of performed cleanups due to the cache size being over the limit. The value is shown in the output of “ccache -s”.

- Added support for relocating debug info directory using `-fdebug-prefix-map`. This allows for cache hits even when `hash_dir` is used in combination with `base_dir`.

- Added a new “cache hit rate” field to the output of “ccache -s”.

- Added support for caching compilation of assembler code produced by e.g. “gcc -S file.c”.

- Added support for cuda including the -optf/--options-file option.

- Added support for Fortran 77.

- Added support for multiple `-arch` options to produce “fat binaries”.

- Multiple identical `-arch` arguments are now handled without bailing.

- The concatenated form of some long compiler options is now recognized, for example when using `-isystemPATH` instead of `-isystem PATH`.

- If hard-linking is enabled and but fails (e.g. due to cross-device linking), ccache now falls back to copying instead of running the compiler.

- Made the `hash_dir` option only have effect when generating debug info.

- ccache now knows how to convert absolute paths to relative paths inside dependency files when using `base_dir`.

- Improved parsing of `-g*` options.

- Made ccache understand `-Wp,-D*` options.

- ccache now understands the undocumented `-coverage` (only one dash) GCC option.

- Names of included files are no longer included in the hash of the compiler’s preprocessed output. This leads to more potential cache hits when not using the direct mode.

- Increased buffer size used when reading file data. This improves performance slightly.

### Bug fixes

- Bail out on too hard compiler option `-P`.

- Fixed Clang test suite when running on Linux.

- Fixed build and test for MinGW32 and Windows.

## Ccache 3.2.9

Release date: 2016-09-28

### Bug fixes

- Fixed a regression in ccache 3.2.8: ccache could get confused when using the compiler option `-Wp,` to pass multiple options to the preprocessor, resulting in missing dependency files from direct mode cache hits.

## Ccache 3.2.8

Release date: 2016-09-07

### Bug fixes

- Fixed an issue when compiler option `-Wp,-MT,path` is used instead of `-MT path` (and similar for `-MF`, `-MP` and `-MQ`) and `run_second_cpp` (`CCACHE_CPP2`) is enabled.

- ccache now understands the undocumented `-coverage` (only one dash) GCC option.

## Ccache 3.2.7

Release date: 2016-07-20

### Bug fixes

- Fixed a bug which could lead to false cache hits for compiler command lines with a missing argument to an option that takes an argument.

- ccache now knows how to work around a glitch in the output of GCC 6’s preprocessor.

## Ccache 3.2.6

Release date: 2016-07-12

### Bug fixes

- Fixed build problem on QNX, which lacks “SA_RESTART”.

- Bail out on compiler option `-fstack-usage` since it creates a `.su` file which ccache currently doesn’t handle.

- Fixed a bug where (due to ccache rewriting paths) the compiler could choose incorrect include files if `CCACHE_BASEDIR` is used and the source file path is absolute and is a symlink.

## Ccache 3.2.5

Release date: 2016-04-17

### New features and enhancements

- Only pass Clang-specific `-stdlib=` to the preprocessor.

- Improved handling of stale NFS handles.

- Made it harder to misinterpret documentation of boolean environment settings' semantics.

### Bug fixes

- Include m4 files used by configure.ac in the source dist archives.

- Corrected “Performance” section in the manual regarding `_DATE`, `__TIME__` and `__FILE__` macros.

- Fixed build on Solaris 10+ and AIX 7.

- Fixed failure to create directories on QNX.

- Don’t (try to) update manifest file in “read-only” and “read-only direct” modes.

- Fixed a bug in caching of `stat` system calls in “file_stat_matches sloppiness mode”.

- Fixed bug in hashing of Clang plugins, leading to unnecessary cache misses.

- Fixed --print-config to show “pch_defines sloppiness”.

- The man page is now built when running “make install” from Git repository sources.

## Ccache 3.2.4

Release date: 2015-10-08

### Bug fixes

- Fixed build error related to zlib on systems with older make versions (regression in ccache 3.2.3).

- Made conversion-to-bool explicit to avoid build warnings (and potential runtime errors) on legacy systems.

- Improved signal handling: Kill compiler on SIGTERM; wait for compiler to exit before exiting; die appropriately.

- Minor fixes related to Windows support.

- The correct compression level is now used if compression is requested.

- Fixed a bug where cache cleanup could be run too early for caches larger than 64 GiB on 32-bit systems.

## Ccache 3.2.3

Release date: 2015-08-16

### New features and enhancements

- Added support for compiler option `-gsplit-dwarf`.

### Bug fixes

- Support external zlib in nonstandard directory.

- Avoid calling `exit()` inside an exit handler.

- Let exit handler terminate properly.

- Bail out on compiler option `--save-temps` in addition to `-save-temps`.

- Only log “Disabling direct mode” once when failing to read potential include files.

## Ccache 3.2.2

Release date: 2015-05-10

### New features and enhancements

- Added support for `CCACHE_COMPILERCHECK=string:<value>`. This is a faster alternative to `CCACHE_COMPILERCHECK=<command>` if the command’s output can be precalculated by the build system.

- Add support for caching code coverage results (compiling for gcov).

### Bug fixes

- Made hash of cached result created with and without `CCACHE_CPP2` different. This makes it possible to rebuild with `CCACHE_CPP2` set without having to clear the cache to get new results.

- Don’t try to reset a nonexistent stats file. This avoids “No such file or directory” messages in the ccache log when the cache directory doesn’t exist.

- Fixed a bug where ccache deleted Clang diagnostics after compiler failures.

- Avoid performing an unnecessary copy of the object file on a cache miss.

- Bail out on too hard compiler option `-fmodules`.

- Bail out on too hard compiler option `-fplugin=libcc1plugin` (interaction with GDB).

- Fixed build error when compiling ccache with recent Clang versions.

- Removed signal-unsafe code from signal handler.

- Corrected logic for when to output cached stderr.

- Wipe the whole cached result on failure retrieving a cached file.

- Fixed build error when compiling ccache with recent Clang versions.

## Ccache 3.2.1

Release date: 2014-12-10

### Bug fixes

- Fixed regression in temporary file handling, which lead to incorrect permissions for stats, manifest and ccache.conf files in the cache.

- `CACHEDIR.TAG` files are now created in the [0-9a-f] subdirectories so that ccache.conf is not lost in backups.

- Made the default cache size suffix `G`, as previously documented.

- `-fdiagnostics-color=auto` is now passed to the compiler even if stderr is redirected. This fixes a problem when, for instance, a configure test probes if the compiler (wrapped via ccache) supports `-fdiagnostics-color=auto`.

- Added missing documentation for `max_files` and `max_size` configuration options.

## Ccache 3.2

Release date: 2014-11-17

### New features and enhancements

- Added support for configuring ccache via one or several configuration files instead of via environment variables. Environment variables still have priority but are no longer the recommended way of customizing ccache behavior. See the manual for more information.

- Added support for compiler error/warning messages with color.

- Made creation of temporary directories and cache directories smarter to avoid unnecessary `stat` calls.

- Improved efficiency of the algorithm that scans for `_DATE` and `__TIME__` tokens in the hashed source code.

- Added support for several binaries (separated by space) in `CCACHE_PREFIX`.

- The `-c` option is no longer passed to the preprocessor. This fixes problems with Clang and Solaris’s C++ compiler.

- ccache no longer passes preprocessor options like `-D` and `-I` to the compiler when compiling preprocessed output. This fixes warnings emitted by Clang.

- Compiler options `-fprofile-generate`, `-fprofile-arcs`, `-fprofile-use` and `-fbranch-probabilities` are now handled without bailing.

- Added support for Clang’s `--serialize-diagnostics` option, storing the diagnostics file (`.dia`) in the cache.

- Added support for precompiled headers when using Clang.

- Added support for Clang `.pth` (pretokenized header) files.

- Changed the `-x` language option to use the new objective C standard for GCC and Clang.

- On a cache miss, ccache now instructs the compiler to create the object file at the real destination and then copies the file into the cache instead of the other way around. This is needed to support compiler options like `-fprofile-arcs` and `--serialize-diagnostics`.

- ccache now checks that included files' ctimes aren’t too new. This check can be turned off by adding `include_file_ctime` to the “ccache sloppiness” setting.

- Added possibility to get cache hits based on filename, size, mtime and ctime only. On other words, source code files are not even read, only stat-ed. This operation mode is opt-in by adding `file_stat_matches` to the “ccache sloppiness” setting.

- The filename part of options like `-Wp,-MDfilename` is no longer included in the hash since the filename doesn’t have any bearing on the result.

- Added a “read-only direct” configuration setting, which is like the ordinary read-only setting except that ccache will only try to retrieve results from the cache using the direct mode, not the preprocessor mode.

- The display and interpretation of cache size has been changed to use SI units.

- Default cache size is now 5 GB (was previously 1 GiB).

- Added configuration option to set the compression level of compressed object files in the cache.

- Added support for `@file` and `-@file` arguments (reading options from a file).

- `-Wl,` options are no longer included in the hash since they don’t affect compilation.

- Bail out on too hard compiler option `-Wp,-P`.

- Optimized MD4 calculation code on little-endian systems.

- Various improvements and fixes on win32.

- Improved logging to the ccache log file.

- Added `--dump-manifest` command-line option for debugging purposes.

- Added `--with-bundled-zlib` configure option.

- Upgraded bundled zlib to version 1.2.8.

- Improved `dev.mk` to be more platform independent.

- Made the test suite work with Clang and gcc-llvm on OS X.

- Various other improvements of the test suite.

### Bug fixes

- Any previous `.stderr` is now removed from the cache when recaching.

- Fixed an issue when handling the `-arch` compiler option with an argument.

- Fixed race condition when creating the initial cache directory.

- Fixed test suite failures when `CC` is a ccache-wrapped compiler.

## Ccache 3.1.12

Release date: 2016-07-12

### Bug fixes

- Fixed a bug where (due to ccache rewriting paths) the compiler could choose incorrect include files if `CCACHE_BASEDIR` is used and the source file path is absolute and is a symlink.

## Ccache 3.1.11

Release date: 2015-03-07

### Bug fixes

- Fixed bug which could result in false cache hits when source code contains `'"'` followed by `" /*"` or `" //"` (with variations).

- Made hash of cached result created with and without `CCACHE_CPP2` different. This makes it possible to rebuild with `CCACHE_CPP2` set without having to clear the cache to get new results.

- Don’t try to reset a nonexistent stats file. This avoids “No such file or directory” messages in the ccache log when the cache directory doesn’t exist.

## Ccache 3.1.10

Release date: 2014-10-19

### New features and enhancements

- Added support for the `-Xclang` compiler option.

- Improved handling of exit code of internally executed processes.

- Zero length object files in the cache are now rejected as invalid.

- Bail out on option `-gsplit-dwarf` (since it produces multiple output files).

- Compiler option `-fdebug-prefix-map` is now ignored (not part of the hash). (The `-fdebug-prefix-map` option may be used in combination with `CCACHE_BASEDIR` to reuse results across different directories.)

- Added note in documentation that `--ccache-skip` currently does not mean “don’t hash the following option”.

- To enable support for precompiled headers (PCH), `CCACHE_SLOPPINESS` now also needs to include the new `pch_defines` sloppiness. This is because ccache can’t detect changes in the source code when only defined macros have been changed.

- Stale files in the internal temporary directory (`<ccache_dir>/tmp`) are now cleaned up if they are older than one hour.

### Bug fixes

- Fixed path canonicalization in `make_relative_path()` when path doesn’t exist.

- Fixed bug in `common_dir_prefix_length()`. This corrects the `CCACHE_BASEDIR` behavior.

- ccache no longer tries to create the cache directory when `CCACHE_DISABLE` is set.

- Fixed bug when reading manifests with a very large number of file info entries.

- Fixed problem with logging of current working directory.

## Ccache 3.1.9

Release date: 2013-01-06

### Bug fixes

- The EAGAIN signal is now handled correctly when emitting cached stderr output. This fixes a problem triggered by large error outputs from the compiler.

- Subdirectories in the cache are no longer created in read-only mode.

- Fixed so that ccache’s log file descriptor is not made available to the compiler.

- Improved error reporting when failing to create temporary stdout/stderr files when executing the compiler.

- Disappearing temporary stdout/stderr files are now handled gracefully.

### Other

- Fixed test suite to work on ecryptfs.

## Ccache 3.1.8

Release date: 2012-08-11

### New features and enhancements

- Made paths to dependency files relative in order to increase cache hits.

- Added work-around to make ccache work with buggy GCC 4.1 when creating a pre-compiled header.

- Clang plugins are now hashed to catch plugin upgrades.

### Bug fixes

- Fixed crash when the current working directory has been removed.

- Fixed crash when stderr is closed.

- Corrected a corner case when parsing backslash escapes in string literals.

- Paths are now correctly canonicalized when computing paths relative to the base directory.

### Other

- Made git version macro work when compiling outside of the source directory.

- Fixed `static_assert` macro definition clash with GCC 4.7.

## Ccache 3.1.7

Release date: 2012-01-08

### Bug fixes

- Non-writable `CCACHE_DIR` is now handled gracefully when `CCACHE_READONLY` is set.

- Made failure to create files (typically due to bad directory permissions) in the cache directory fatal. Previously, such failures were silently and erroneously flagged as “compiler produced stdout”.

- Both the `-specs=file` and `--specs=file` forms are now recognized.

- Added recognition and hashing of GCC plugins specified with `-fplugin=file`.

- `CCACHE_COMPILERCHECK` now also determines how to hash explicit specs files (`-specs=file`).

- Added `CPATH`, `C_INCLUDE_PATH` and similar environment variables to the hash to avoid false cache hits when such variables have changed.

- Corrected log message when unify mode is enabled.

- Reverted the GCC bug compatibility introduced in ccache 3.1.5 for `-MT`/`-MQ` options with concatenated arguments. (The bug is fixed in recent GCC versions.)

### Other

- Corrected license header for `mdfour.c`.

- Improved documentation on how to fix bad object files in the cache.

## Ccache 3.1.6

Release date: 2011-08-21

### New features and enhancements

- Rewrite argument to `--sysroot` if `CCACHE_BASEDIR` is used.

### Bug fixes

- Don’t crash if `getcwd()` fails.

- Fixed alignment of “called for preprocessing” counter.

## Ccache 3.1.5

Release date: 2011-05-29

### New features and enhancements

- Added a new statistics counter named “called for preprocessing”.

- The original command line is now logged to the file specified with `CCACHE_LOGFILE`.

- Improved error logging when system calls fail.

- Added support for rewriting absolute paths in `-F`/`-iframework` GCC options.

- Improved order of statistics counters in `ccache -s` output.

### Bug fixes

- The `-MF`/`-MT`/`-MQ` options with concatenated argument are now handled correctly when they are last on the command line.

- ccache is now bug compatible with GCC for the `-MT`/`-MQ` options with concatenated arguments.

- Fixed a minor memory leak.

- Systems that lack (and don’t need to be linked with) libm are now supported.

## Ccache 3.1.4

Release date: 2011-01-09

### Bug fixes

- Made a work-around for a bug in `gzputc()` in zlib 1.2.5.

- Corrupt manifest files are now removed so that they won’t block direct mode hits.

- ccache now copes with file systems that don’t know about symbolic links.

- The file handle is now correctly closed on write error when trying to create a cache dir tag.

## Ccache 3.1.3

Release date: 2010-11-28

### Bug fixes

- The -MFarg, -MTarg and -MQarg compiler options (i.e, without space between option and argument) are now handled correctly.

### Other

- Portability fixes for HP-UX 11.00 and other less common systems.

## Ccache 3.1.2

Release date: 2010-11-21

### Bug fixes

- Bail out on too hard compiler options `-fdump-*`.

- NULL return values from malloc/calloc of zero bytes are now handled correctly.

- Fixed issue when parsing precompiler output on AIX.

### Other

- Improved documentation on which information is included in the hash sum.

- Made the “too new header file” test case work on file systems with unsynchronized clocks.

- The test suite now also works on systems that lack a /dev/zero.

## Ccache 3.1.1

Release date: 2010-11-07

### Bug fixes

- ccache now falls back to preprocessor mode when a non-regular include file (device, socket, etc) has been detected so that potential hanging due to blocking reads is avoided.

- CRC errors are now detected when decompressing compressed files in the cache.

- Fixed potential object file corruption race on NFS.

- Minor documentation corrections.

- Fixed configure detection of ar.

- ccache development version (set by dev.mk) now works with gits whose `describe` command doesn’t understand `--dirty`.

### Other

- Minor debug log message improvements.

## Ccache 3.1

Release date: 2010-09-16

### New features and enhancements

- Added support for hashing the output of a custom command (e.g. `%compiler% --version`) to identify the compiler instead of stat-ing or hashing the compiler binary. This can improve robustness when the compiler (as seen by ccache) actually isn’t the real compiler but another compiler wrapper.

- Added support for caching compilations that use precompiled headers. (See the manual for important instructions regarding this.)

- Locking of the files containing statistics counters is now done using symlinks instead of POSIX locks. This should make ccache behave a lot better on file systems where POSIX locks are slow or broken (e.g. NFS on some systems).

- Manifest files are now updated without the need of taking locks.

- Updates of statistics counters are now always done in one of the sub-level statistics files. This reduces lock contention, which especially improves performance on slow NFS mounts.

- Reading and writing of statistics counters has been made forward-compatible (unknown counters are retained).

- Files are now read without using `mmap()`. This has two benefits: it’s more robust against file changes during reading and it improves performance on poor systems where `mmap()` doesn’t use the disk cache.

- Added `.cp` and `.CP` as known C++ suffixes.

- Improved logging.

- Added `-install_name` as an option known to take an argument. (This improves statistics when using the Darwin linker.)

### Bug fixes

- Non-fatal error messages are now never printed to stderr but logged instead.

- Fixed a bug affecting failing commands when `--ccache-skip` is used.

- Made `--ccache-skip` work for all options.

- EINTR is now handled correctly.

### Other

- Work on porting ccache to win32 (native), mostly done by Ramiro Polla. The port is not yet finished, but will hopefully be complete in some subsequent release.

- Added a `--nostats` flag to the performance benchmark program.

- Made the performance benchmark program more accurate when measuring cache hits.

- Added a new test framework for unit tests written in C.

- Got rid of `configure-dev`; dev mode is now given by `dev.mk.in` presence.

- Improved documentation on how to combine ccache with other compiler wrappers (like `distcc`).

- New `LICENSE.txt` file with licensing and copyright details about bundled source code.

- New `AUTHORS.txt` file with a list of ccache contributors.

- New `HACKING.txt` file with some notes about ccache code conventions.

## Ccache 3.0.1

Release date: 2010-07-15

### Bug fixes

- The statistics counter “called for link” is now correctly updated when linking with a single object file.

- Fixed a problem with out-of-source builds.

## Ccache 3.0

Release date: 2010-06-20

### General

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

### 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. Because of this, you might as well clear the old cache directory with `ccache --clear` if you want, unless you plan to keep using an older ccache version.

### New features and enhancements

- ccache now has a “direct mode” where it computes a hash of the source code (including all included files) and compiler options without running the preprocessor. By not running the preprocessor, CPU usage is reduced; the speed is somewhere between 1 and 5 times that of ccache running in traditional mode, depending on the circumstances. The 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.

- Support has been added for rewriting absolute paths to relative paths when hashing, in order to increase cache hit rate when building the same source code in different directories even when compiling with `-g` and when using absolute include directory paths. This is done by setting the `CCACHE_BASEDIR` environment variable to an absolute path that specifies which paths to rewrite.

- Object files are now optionally stored compressed in the cache. The runtime cost is negligible, and more files will fit in the ccache directory and in the disk cache. Set `CCACHE_COMPRESS` to enable object file compression. Note that you can’t use compression in combination with the hard link feature.

- 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.

- It is now possible to specify extra files whose contents should be included in the hash sum by setting the `CCACHE_EXTRAFILES` option.

- Added support for Objective-C and Objective-C+\+. The statistics counter “not a C/C++ file” has been renamed to “unsupported source language”.

- Added support for the `-x` compiler option.

- Added support for long command-line options.

- A `CACHEDIR.TAG` file is now created in the cache directory. See https://bford.info/cachedir.

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

- You can relax some checks that ccache does in direct mode by setting `CCACHE_SLOPPINESS`. See the manual for more information.

- `CCACHE_TEMPDIR` no longer needs to be on the same filesystem as `CCACHE_DIR`.

- The default value of `CCACHE_TEMPDIR` has been changed to `$CCACHE_DIR/tmp` to avoid cluttering the top directory.

- Temporary files that later will be moved into the cache are now created in the cache directory they will end up in. This makes ccache more friendly to Linux’s directory layout.

- 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' and cleanup semantics.

- Improved display of cache max size values.

- The following options are no longer hashed in the preprocessor mode: `-imacros`, `-imultilib`, `-iprefix`, `-iquote`, `-isysroot`, `-iwithprefix`, `-iwithprefixbefore`, `-nostdinc`, `-nostdinc++` and `-U`.

### Bug fixes

- Various portability improvements.

- Improved detection of home directory.

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

- Fixed NFS issues.

- Computation of the hash sum has been improved to decrease the risk of hash collisions. For instance, the compiler options `-X -Y` and `-X-Y` previously contributed equally to the hash sum.

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

- Errors when using multiple `-arch` compiler options are now noted as “unsupported compiler option”.

- `-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.

- The compiler options `-Xassembler`, `-b`, `-G` and `-V` are now correctly recognized as taking an argument.

- 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`.

- 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.

- Improved detection of recursive invocation.

- The ccache binary is now not unconditionally stripped when installing.

- Statistics counters are now correctly updated for -E option failures and internal errors.