CMake 3.27 deprecates compatibility with CMake < 3.5. Update tests that
do not cover older interfaces to avoid the deprecation warning.
Follow the pattern from:
* commit 7b07ccdd2b (Tests/*Only: Update cmake_minimum_required versions,
2020-06-15, v3.19.0-rc1~629^2~1)
* commit 72e7c45e98 (Tests: Bump CMake minimum required in tests to 2.8.12,
2020-12-22, v3.20.0-rc1~224^2)
* commit f6b4db365a (Tests: bump cmake_minimum_required version to 2.8.12,
2021-04-04, v3.21.0-rc1~372^2)
Also remove explicit `cmake_policy` settings made redundant by the
version.
Due to MCST LCC compiler identification is now changed to LCC,
there should be a way for old projects to still identify it as GNU,
as it was before.
This commits adds the policy:
CMP0129: Compiler id for MCST LCC compilers is now LCC, not GNU.
This policy controls such a behavior.
OLD behaivior is to treat LCC as GNU, NEW is to treat is as LCC.
Divert LCC compiler as a new one, instead of treating it as GNU.
Since old times, Elbrus C/C++/Fortran Compiler (LCC) by MCST has been
passing checks for GNU compilers, so it has been identified as GNU.
Now, with intent of seriously upstreaming its support, it has been
added as a separate LCC compiler, and its version displays not a
supported GCC version, but LCC version itself (e.g. LCC 1.25.19 instead
of GNU 7.3.0).
This commit adds its support for detection, and also converts basically
every check like 'is this compiler GNU?' to 'is this compiler GNU or
LCC?'. The only places where this check is untouched, is where it
regards other platforms where LCC is unavailable (primarily non-Linux),
and where it REALLY differs from GNU compiler.
Note: this transition may break software that are already ported to
Elbrus, but hardly relies that LCC will be detected as GNU; still such
software is not known.
Since 3.19, CMake generates a deprecation warning when using a minimum
version less than 2.8.12. This eliminates those warnings generated
during tests, which are typically hidden from the user and developer but
are being generated nonetheless.
* Disable the system include unused variable test in ExportImport when
clang is in MSVC compatible mode.
* Disable CxxDialect testcase when clang is in MSVC compatible mode, as
it doesn't support `typeof`.
* Teach Module.WriteCompilerDetectionHeader to treat clang-cl as MSVC.
* Disable the SystemIncludeDirectories testcase within
IncludeDirectories when clang is in MSVC compatible mode.
* Disable the CMakeOnly.CheckCXXCompilerFlag testcase when clang is in
MSVC compatible mode.
* Treat clang-cl as MSVC in LinkOptions.cmake in the try_run and
try_compile testcases.
Since commit v3.3.0-rc1~397^2 (Check*CompilerFlag: Refactor method used
to pass flags, 2015-02-24) these check modules pass the flags to the
compiler front-end during linking as well as during compilation. This
breaks checks for flags like '-x c++' that are meant only for the
compilation step. Revert the change and add a test covering a
compiler-only flag.
Brad King