Author: Reagan Date: 2024-05-24T23:48:13-04:00 New Revision: 778dbcbbb5c4e462231e812ab463b586555b6a0a
URL: https://github.com/llvm/llvm-project/commit/778dbcbbb5c4e462231e812ab463b586555b6a0a DIFF: https://github.com/llvm/llvm-project/commit/778dbcbbb5c4e462231e812ab463b586555b6a0a.diff LOG: [clang] Add /Zc:__STDC__ flag to clang-cl (#68690) This commit adds the /Zc:\_\_STDC\_\_ argument from MSVC, which defines \_\_STDC_\_. This means, alongside stronger feature parity with MSVC, that things that rely on \_\_STDC\_\_, such as autoconf, can work. Link to MSVC documentation of this flag: https://learn.microsoft.com/en-us/cpp/build/reference/zc-stdc?view=msvc-170 Added: clang/test/Driver/ms-define-stdc.c clang/test/Preprocessor/stdc-ms-extension.cpp Modified: clang/docs/ReleaseNotes.rst clang/include/clang/Basic/LangOptions.def clang/include/clang/Driver/Options.td clang/lib/Driver/ToolChains/Clang.cpp clang/lib/Frontend/InitPreprocessor.cpp Removed: ################################################################################ diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst index e40b236c914d9..d023f53754cb3 100644 --- a/clang/docs/ReleaseNotes.rst +++ b/clang/docs/ReleaseNotes.rst @@ -342,6 +342,10 @@ New Compiler Flags ``__attribute__((section(...)))``. This enables linker GC to collect unused symbols without having to use a per-symbol section. +- ``-fms-define-stdc`` and its clang-cl counterpart ``/Zc:__STDC__``. + Matches MSVC behaviour by defining ``__STDC__`` to ``1`` when + MSVC compatibility mode is used. It has no effect for C++ code. + Deprecated Compiler Flags ------------------------- diff --git a/clang/include/clang/Basic/LangOptions.def b/clang/include/clang/Basic/LangOptions.def index 09eb92d6f10d2..4061451b2150a 100644 --- a/clang/include/clang/Basic/LangOptions.def +++ b/clang/include/clang/Basic/LangOptions.def @@ -300,6 +300,7 @@ LANGOPT(HIPStdParInterposeAlloc, 1, 0, "Replace allocations / deallocations with LANGOPT(OpenACC , 1, 0, "OpenACC Enabled") +LANGOPT(MSVCEnableStdcMacro , 1, 0, "Define __STDC__ with '-fms-compatibility'") LANGOPT(SizedDeallocation , 1, 0, "sized deallocation") LANGOPT(AlignedAllocation , 1, 0, "aligned allocation") LANGOPT(AlignedAllocationUnavailable, 1, 0, "aligned allocation functions are unavailable") diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td index 9a5bffce20460..de2f245fb29f8 100644 --- a/clang/include/clang/Driver/Options.td +++ b/clang/include/clang/Driver/Options.td @@ -2981,6 +2981,10 @@ def fms_compatibility : Flag<["-"], "fms-compatibility">, Group<f_Group>, Visibility<[ClangOption, CC1Option, CLOption]>, HelpText<"Enable full Microsoft Visual C++ compatibility">, MarshallingInfoFlag<LangOpts<"MSVCCompat">>; +def fms_define_stdc : Flag<["-"], "fms-define-stdc">, Group<f_Group>, + Visibility<[ClangOption, CC1Option, CLOption]>, + HelpText<"Define '__STDC__' to '1' in MSVC Compatibility mode">, + MarshallingInfoFlag<LangOpts<"MSVCEnableStdcMacro">>; def fms_extensions : Flag<["-"], "fms-extensions">, Group<f_Group>, Visibility<[ClangOption, CC1Option, CLOption]>, HelpText<"Accept some non-standard constructs supported by the Microsoft compiler">, @@ -8306,6 +8310,9 @@ def _SLASH_vd : CLJoined<"vd">, HelpText<"Control vtordisp placement">, Alias<vtordisp_mode_EQ>; def _SLASH_X : CLFlag<"X">, HelpText<"Do not add %INCLUDE% to include search path">, Alias<nostdlibinc>; +def _SLASH_Zc___STDC__ : CLFlag<"Zc:__STDC__">, + HelpText<"Define __STDC__">, + Alias<fms_define_stdc>; def _SLASH_Zc_sizedDealloc : CLFlag<"Zc:sizedDealloc">, HelpText<"Enable C++14 sized global deallocation functions">, Alias<fsized_deallocation>; diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp index adb1b2ff566cb..97e451cfe2acb 100644 --- a/clang/lib/Driver/ToolChains/Clang.cpp +++ b/clang/lib/Driver/ToolChains/Clang.cpp @@ -7026,8 +7026,12 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA, options::OPT_fms_compatibility, options::OPT_fno_ms_compatibility, (IsWindowsMSVC && Args.hasFlag(options::OPT_fms_extensions, options::OPT_fno_ms_extensions, true))); - if (IsMSVCCompat) + if (IsMSVCCompat) { CmdArgs.push_back("-fms-compatibility"); + if (!types::isCXX(Input.getType()) && + Args.hasArg(options::OPT_fms_define_stdc)) + CmdArgs.push_back("-fms-define-stdc"); + } if (Triple.isWindowsMSVCEnvironment() && !D.IsCLMode() && Args.hasArg(options::OPT_fms_runtime_lib_EQ)) diff --git a/clang/lib/Frontend/InitPreprocessor.cpp b/clang/lib/Frontend/InitPreprocessor.cpp index 68760e00003e0..e8c8a5175f8f4 100644 --- a/clang/lib/Frontend/InitPreprocessor.cpp +++ b/clang/lib/Frontend/InitPreprocessor.cpp @@ -432,7 +432,8 @@ static void InitializeStandardPredefinedMacros(const TargetInfo &TI, // [C++] Whether __STDC__ is predefined and if so, what its value is, // are implementation-defined. // (Removed in C++20.) - if (!LangOpts.MSVCCompat && !LangOpts.TraditionalCPP) + if ((!LangOpts.MSVCCompat || LangOpts.MSVCEnableStdcMacro) && + !LangOpts.TraditionalCPP) Builder.defineMacro("__STDC__"); // -- __STDC_HOSTED__ // The integer literal 1 if the implementation is a hosted diff --git a/clang/test/Driver/ms-define-stdc.c b/clang/test/Driver/ms-define-stdc.c new file mode 100644 index 0000000000000..d5e873d21a76b --- /dev/null +++ b/clang/test/Driver/ms-define-stdc.c @@ -0,0 +1,11 @@ +// Note: %s must be preceded by --, otherwise it may be interpreted as a +// command-line option, e.g. on Mac where %s is commonly under /Users. +// +// Note: see also cl-zc.cpp + +// RUN: %clang_cl /TC /dev/null /E -Xclang -dM /Zc:__STDC__- 2>&1 | FileCheck %s --check-prefix=ZCSTDCIGNORED +// ZCSTDCIGNORED-NOT: #define __STDC__ 1 +// ZCSTDCIGNORED: argument unused during compilation + +// RUN: not %clang -Xclang -fno-ms-define-stdc %s 2>&1 | FileCheck %s --check-prefix="NOARG" +// NOARG: error: unknown argument: '-fno-ms-define-stdc' diff --git a/clang/test/Preprocessor/stdc-ms-extension.cpp b/clang/test/Preprocessor/stdc-ms-extension.cpp new file mode 100644 index 0000000000000..6e9fa6055306e --- /dev/null +++ b/clang/test/Preprocessor/stdc-ms-extension.cpp @@ -0,0 +1,9 @@ +// RUN: %clang_cl /TC /dev/null /E -Xclang -dM 2> /dev/null | FileCheck -match-full-lines %s --check-prefix=NOSTDC +// RUN: %clang_cl /TC /dev/null /E -Xclang -dM /Zc:__STDC__ 2> /dev/null | FileCheck -match-full-lines %s --check-prefix=YESSTDC +// __STDC__ should never be defined in C++ mode with fms-compatibility. +// RUN: %clang_cl /dev/null /E -Xclang -dM 2>&1 | FileCheck %s --check-prefix=NOSTDC +// RUN: %clang_cl /dev/null /E -Xclang -dM /Zc:__STDC__ 2>&1 | FileCheck %s --check-prefix=ZCSTDCIGNORED +// YESSTDC: #define __STDC__ 1 +// NOSTDC-NOT: #define __STDC__ 1 +// ZCSTDCIGNORED-NOT: #define __STDC__ 1 +// ZCSTDCIGNORED: argument unused during compilation _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
