Refactoring in commit 6b85166920 (ENH: Refactor find_library search
logic, 2008-09-22, v2.8.0~1665) dropped a call to `FileExists` on the
path under the assumption that the presence of a file in a directory
listing means it exists. However, dropping that also dropped a check
that verifies the file is readable. Restore the `FileExists` call to
ensure that we only find readable libraries.
In the same spirit as the REQUIRED keyword on find_package, this will
stop cmake execution with an error on a failed find_program, find_file,
find_path or find_library.
Teach the find_package, find_library, find_program, find_path, and
find_file commands to print debug log messages when enabled by the
`--debug-find` command-line option or `CMAKE_FIND_DEBUG_MODE` variable.
The `FIND_LIBRARY_USE_LIB<arch>_PATHS` global properties ask
`find_library` to look in `lib<arch>` directories automatically before
corresponding `lib` directories. However, if `lib<arch>` is just a
symlink to `lib` (or vice-versa) then we should skip adding the
`lib<arch>` path. Such symlinks typically only exist to satisfy
software that expects the `lib<arch>` path to be available.
Fixes: #16687
Since commit v3.3.0-rc1~430^2 (Teach find_(library|file|path) to get
prefixes from PATH, 2015-02-18) we search in <prefix>/include and
<prefix>/lib directories for prefixes with bin directories in the PATH
environment variable. The motivation was to support MSYS, MinGW and
similar Windows platforms in their default environments automatically.
At the time this behavior was thought to be worthwhile in general.
Suggested-by: Chuck Atkins <chuck.atkins@kitware.com>
The find_package command already knows how to compute installation
prefixes from PATH. Use the same approach to establish prefixes for
find_library, find_file, and find_path to use to look in directories
like "<prefix>/lib[/<arch>]" and "<prefix>/include" for libraries and
headers. This will reduce the amount of configuration end users need to
do to establish a work environment rooted under a specific prefix.
We use cmGlobalGenerator::GetDirectoryContent to avoid repeating
directory listings. However, GetDirectoryContent loads content from
disk at most once. This breaks find_library calls that occur when disk
content has changed since preceding find_library calls.
Teach cmGlobalGenerator::GetDirectoryContent to save the directory
modification time when content is loaded and re-load content if it
changes.
Create a RunCMake.find_library test with a case covering this.
Marc Chevrier