`clang-tidy` does not infer driver mode if it is not provided with a
JSON compilation database. This is exactly the way cmake launches it.
Hence clang-tidy will only use the default driver mode. Add an explicit
driver mode argument to avoid this.
Since commit d44c0db0b2 (clang: setup correct configuration in gnu mode,
2019-02-20, v3.15.0-rc1~41^2~5) we support the GNU-like Clang that
targets the MSVC ABI. However, Clang cannot compile with the MSVC
standard library unless it runs in a mode aware of C++14 (since MSVC
itself does not even have a lower mode). When `CMAKE_CXX_STANDARD` is
set to 98 or 11, use C++14 anyway.
Since Clang's default mode is aware of C++14, another option is to not
add any flags for 98 or 11. However, if a future Clang version ever
defaults to a higher C++ standard, setting the standard to 98 or 11
should at least not use a mode higher than 14.
Also revert test updates from commit 4819ff9647 (Tests: fix failures
with gnu mode clang on windows, 2019-03-21, v3.15.0-rc1~41^2~3) that
were meant to work around the standard selection problem.
Fixes: #19496
Use the infrastructure added by commit 646fb1a646 (CompileFeatures:
memoize C++ compilers with full language level support, 2019-03-27) to
avoid using a `try_compile` to check for C++14 feature support when the
running compiler is known to have all features.
Use the infrastructure added by commit 646fb1a646 (CompileFeatures:
memoize C++ compilers with full language level support, 2019-03-27) to
avoid using a `try_compile` to check for C++11 feature support when the
running compiler is known to have all features.
Use the infrastructure added by commit 646fb1a646 (CompileFeatures:
memoize C++ compilers with full language level support, 2019-03-27) to
avoid using a `try_compile` to check for C++98 feature support when the
running compiler is known to have all features.
Apply the optimization from commit v3.10.0-rc1~131^2 (MSVC: Avoid
unnecessary C++ feature detection steps, 2017-09-11) to the case of
Clang simulating a version of MSVC that does not define standards.
Issue: #17274
Android NDK r16b comes with
Android clang version 5.0.300080 (based on LLVM 5.0.300080)
Although it claims version 5, it does not support the `-std=c++17`
or `-std=c++2a` flags that upstream Clang does.
Android NDK r17-beta1 comes with
Android (4639204 based on r316199) clang version 6.0.1
that does have the flags.
Condition all calls to `_record_compiler_features_{c,cxx}` on
`_result EQUAL 0` so that adding new language standards later does
not need to update them. Avoid some duplicate compiler version
checks by conditioning C11 and CXX14 feature recording on the
existence of `CMAKE_{C11,CXX14}_STANDARD_COMPILE_OPTION` (whose
setting already used the version check).
Drop the 'UNIX' condition on Clang compiler features. This enables
use of compile features with MinGW Clang, though additional work may
be needed for clang-cl.
Prior to commit v3.4.0-rc1~71^2 (Project: Determine default language
dialect for the compiler, 2015-09-15) we always guessed the default
language standard dialect based on the compiler version. This was not
reliable so that commit switched to computing the default language
standard dialect while detecting the compiler id.
When a toolchain file uses CMakeForceCompiler to set the compiler id
then the detection does not occur. Therefore commit v3.4.0-rc1~54^2
(Project: Don't require computed default dialect if compiler was forced,
2015-09-22) made the lack of detection an error only if the compiler was
not forced. However, this means that projects using CMakeForceCompiler
no longer even get the guess that we had before so <LANG>_COMPILER does
not work.
Due to the sophistication of CMake's compiler detection logic projects
should be ported away from using CMakeForceCompiler. In the meantime,
restore a guess of the default language standard dialect when the
compiler is forced.
Commit 7235334a (Project: Determine default language dialect for the
compiler., 2015-09-15) introduced a mechanism to determine the default
dialect used for the running compiler. If conditions in
the <CompilerId>-<Lang>.cmake file are such that compile features for
that version of the compiler should be supported, the _DEFAULT_STANDARD
is set to the computed value.
However, the CMakeForceCompiler module allows users to bypass execution of the
compiler by CMake. In that case, do not set the _DEFAULT_STANDARD variable at
all, which effectively disables the compile-features where the module is used.
No compile features have ever been recorded where the module is used so no
functionality is lost.
If no compiler feature information is known for a given compiler
version, do not set a language standard default either. The two
settings must be recorded consistently.
GNU-CXX already has complex logic and sets the _result to 0 before
tests which may set it to something else.
Change the other modules to be consistent with that.
Teach the compiler identification preprocessor tests to report when
Clang simulates MSVC, and what version. If not MSVC, assume GNU.
Teach compiler information modules Clang-(C|CXX) to recognize when Clang
simulates MSVC and skip loading the GNU information.
Teach the Windows-MSVC platform information to recognize when it is
loaded as the simulated compiler and use that version information
instead of the real compiler's (different) version scheme.
Add platform modules Windows-Clang-(C|CXX) and support module
Windows-Clang to load either Windows-MSVC or Windows-GNU and wrap
the corresponding information macros.
This corresponds to the g++ and clang++
option -fvisibility-inlines-hidden on linux. On Windows with MinGW,
this corresponds to -fno-keep-inline-dllexport. That option is
not supported by clang currently.
While Clang presents an almost identical interface to GNU there will be
some differences. Split the compiler information modules to allow
separate rules for Clang. Start by loading the GNU rules but leave a
place to add Clang-specific information.
Map to the platform and compiler information for GNU because the
compilers are command-line compatible for common operations. Later we
can add Clang-specific features as necessary. We honor the preferred
capitalization is "Clang", not the common mis-spelling "CLang".
