A misconfigured compiler may pass extraneous implicit link directories
to its linker. If they are in `CMAKE_<LANG>_IMPLICIT_LINK_DIRECTORIES`,
CMake may generate extra `-L` flags on mixed-language link lines that
break linking. Add an environment variable that users can set to work
around such misconfiguration of their compilers.
For policy-specific tests, use the version before the policy was
introduced. Otherwise, use 3.5 where possible.
Also, remove `cmake_minimum_required()` and `project()` calls from
individual cases where they are handled by `CMakeLists.txt`.
Parse implicit link information for this compiler to support
mixed-language linking. This was missed by commit 85749766df
(LLVMFlang: Add support for LLVM Flang, 2021-07-07, v3.24.0-rc1~86^2).
Also activate mixed-language test cases that would have caught this.
Issue: #22387
The current regular expression is able to match `/usr/lib/<arch>`,
`/usr/usr/lib/<arch>`, `/usr/usr/usr/lib/<arch>`, ... but not
`/lib/<arch>`.
This behavior ends up causing the detected architecture to
be x86_64-pc-linux-gnu when the Clang compiler is installed on
a "non-system" location (like /opt/llvm-13) which, in turn, makes
almost every 'find_library()' fail because the correct
architecture is x86_64-linux-gnu.
This is due to a typo in commit 764606e256 (CMakeDetermineCompilerABI:
Extract lib arch from implicit object file paths, 2021-04-05,
v3.20.1~10^2), which used `+` instead of `?`.
With flags like `-static-libstdc++` or `-static-libgfortran`, the GNU
compiler driver adds `-Bstatic ... -Bdynamic` around its language
runtime library. Convert the libraries in between these to absolute
paths so that mixed-language linking honors the static runtime
libraries.
The NVHPC compiler does not have any implicit link directories that can
be used to detect `CMAKE_LIBRARY_ARCHITECTURE`, but it does have
implicit object files. Extract implicit object file paths from link
lines and check them for the `CMAKE_LIBRARY_ARCHITECTURE` pattern.
Issue: #22024
The change in commit 657fc3a9a7 (CMakeDetermineCompilerABI: Parse
library arch from versioned paths, 2021-02-03, v3.20.0-rc1~40^2) caused
`CMAKE_LIBRARY_ARCHITECTURE` to be populated on non-multiarch platforms
if their compilers happen to use `$arch/$version` library directories.
Revert the use of versioned library paths.
Fixes: #22024
Teach CMake how to extract `CMAKE_<LANG>_LIBRARY_ARCHITECTURE` from
versioned paths such as `/usr/lib/gcc/x86_64-linux-gnu/9`. These kind of
paths are generated by NVHPC compilers.
It is currently presumed that the linker will generate
a space separated line. This is not the case for some
compilers such as IBM XL where it can output space or
comma separated. This is particularly apparent when IBM XL
is used as the host compiler for CUDA as it generates a comma
separated link line.
