diff options
| -rw-r--r-- | docs/markdown/snippets/msvc_cplusplus_define.md | 15 | ||||
| -rw-r--r-- | mesonbuild/compilers/cpp.py | 10 | ||||
| -rw-r--r-- | test cases/windows/18 msvc cplusplus define/main.cpp | 7 | ||||
| -rw-r--r-- | test cases/windows/18 msvc cplusplus define/meson.build | 14 | ||||
| -rw-r--r-- | test cases/windows/3 cpp/meson.build | 2 |
5 files changed, 47 insertions, 1 deletions
diff --git a/docs/markdown/snippets/msvc_cplusplus_define.md b/docs/markdown/snippets/msvc_cplusplus_define.md new file mode 100644 index 0000000..2c5648d --- /dev/null +++ b/docs/markdown/snippets/msvc_cplusplus_define.md @@ -0,0 +1,15 @@ +## MSVC now sets the __cplusplus #define accurately + +MSVC will always return `199711L` for `__cplusplus`, even when a newer c++ +standard is explicitly requested, unless you pass a specific option to the +compiler for MSVC 2017 15.7 and newer. Older versions are unaffected by this. + +Microsoft's stated rationale is that "a lot of existing code appears to depend +on the value of this macro matching 199711L", therefore for compatibility with +such (MSVC-only) code they will require opting in to the standards-conformant +value. + +Meson now always sets the option if it is available, as it is unlikely that +users want the default behavior, and *impossible* to use the default behavior +in cross-platform code (which frequently breaks as soon as the first person +tries to compile using MSVC). diff --git a/mesonbuild/compilers/cpp.py b/mesonbuild/compilers/cpp.py index fe09b6b..4c24767 100644 --- a/mesonbuild/compilers/cpp.py +++ b/mesonbuild/compilers/cpp.py @@ -734,6 +734,16 @@ class VisualStudioCPPCompiler(CPP11AsCPP14Mixin, VisualStudioLikeCPPCompilerMixi del args[i] return args + def get_always_args(self) -> T.List[str]: + args = super().get_always_args() + + # By default, MSVC has a broken __cplusplus define that pretends to be c++98: + # https://docs.microsoft.com/en-us/cpp/build/reference/zc-cplusplus?view=msvc-160 + # Pass the flag to enable a truthful define, if possible. + if version_compare(self.version, '>= 15.7') and '/Zc:__cplusplus' not in args: + return args + ['/Zc:__cplusplus'] + return args + class ClangClCPPCompiler(CPP11AsCPP14Mixin, VisualStudioLikeCPPCompilerMixin, ClangClCompiler, CPPCompiler): id = 'clang-cl' diff --git a/test cases/windows/18 msvc cplusplus define/main.cpp b/test cases/windows/18 msvc cplusplus define/main.cpp new file mode 100644 index 0000000..bc0b1fd --- /dev/null +++ b/test cases/windows/18 msvc cplusplus define/main.cpp @@ -0,0 +1,7 @@ +int main() { +#if __cplusplus == 199711L + return 1; +#else + return 0; +#endif +} diff --git a/test cases/windows/18 msvc cplusplus define/meson.build b/test cases/windows/18 msvc cplusplus define/meson.build new file mode 100644 index 0000000..9b85ff6 --- /dev/null +++ b/test cases/windows/18 msvc cplusplus define/meson.build @@ -0,0 +1,14 @@ +project('msvc __cplusplus', 'cpp', default_options : ['cpp_std=c++14']) + +cpp = meson.get_compiler('cpp') + +if cpp.get_id() != 'msvc' + error('MESON_SKIP_TEST: test is only relevant for msvc') +elif meson.project_version().version_compare('< 15.7') + error('MESON_SKIP_TEST: test is only relevant for msvc versions >= 15.7') +endif + +test( + 'main', + executable('main', 'main.cpp'), +) diff --git a/test cases/windows/3 cpp/meson.build b/test cases/windows/3 cpp/meson.build index 7b8080e..a9e6569 100644 --- a/test cases/windows/3 cpp/meson.build +++ b/test cases/windows/3 cpp/meson.build @@ -1,4 +1,4 @@ -project('wincpp', 'cpp') +project('wincpp', 'cpp', default_options : ['cpp_std=c++14']) exe = executable('prog', 'prog.cpp') test('wincpp', exe) |