The <LANG>_VISIBILITY_PRESET and VISIBILITY_INLINES_HIDDEN were first
merged in commit v2.8.12~322 (Merge topic 'VISIBILITY_PRESET-property',
2013-06-05) but worked only for shared libraries and executables with
exports. Prior to commit v3.0.0-rc1~581^2 (GenerateExportHeader:
Deprecate add_compiler_export_flags function., 2013-09-02) the
add_compiler_export_flags function was used to add visibility flags to
all targets.
The visibility flags are useful for sources in all target types because
they may be later linked into shared libraries or executables with
exports. Introduce policy CMP0063 to enable them for all target types
while preserving compatibility with existing projects that do not expect
this.
When CMP0003 was first introduced we wanted to link all libraries by
full path. However, some projects had problems on platforms where
find_library would find /usr/lib/libfoo.so when the project really
wanted to link to /usr/lib/<arch>/libfoo.so and had been working by
accident because pre-CMP0003 behavior used -lfoo to link.
We first tried to address that in commit v2.6.0~440 (Teach find_library
to avoid returning library paths in system directories, 2008-01-23) by
returning just "foo" for libraries in implicit link directories. This
caused problems for projects expecting find_library to always return a
full path. We ended up using the solution in commit v2.6.0~366 (...
switch library paths found in implicit link directories to use -l,
2008-01-31). However, the special case for libraries in implicit link
directories has also proven problematic and confusing.
Introduce policy CMP0060 to switch to linking all libraries by full path
even if they are in implicit link directories. Explain in the policy
documentation the factors that led to the original approach and now to
this approach.
Allow directories in the source tree or build tree only if the
install tree is a subdirectory of the source tree or build tree,
as appropriate.
Re-use the test files in the RunCMake.include_directories test
to run in multiple scenarios. Bump the required CMake version
in the test to 3.0 to ensure that the new policy warnings are
emitted correctly.
Set the minimum required version of CMake high enough to avoid the
warning for CMAKE_LEGACY_CYGWIN_WIN32. The warning appears on stderr
and breaks the expected output matching.
Use preprocessor loops and add a unit test for the appropriate
policies. All policies whose value is recorded at target creation
time should be part of this list.
Brad King
Stephen Kelly