Author: Harald van Dijk Date: 2021-01-25T00:56:45Z New Revision: f4537935dcdbf390c863591cf556e76c3abab9c1
URL: https://github.com/llvm/llvm-project/commit/f4537935dcdbf390c863591cf556e76c3abab9c1 DIFF: https://github.com/llvm/llvm-project/commit/f4537935dcdbf390c863591cf556e76c3abab9c1.diff LOG: Suppress non-conforming GNU paste extension in all standard-conforming modes The GNU token paste extension that removes the comma in , ## __VA_ARGS__ conflicts with C99/C++11's requirements when a variadic macro has no named parameters: according to the standard, an invocation as FOO() gives it a single empty argument, and concatenation of anything with an empty argument is well-defined. For this reason, the GNU extension was already disabled in C99 standard-conforming mode. It was not yet disabled in C++11 standard-conforming mode. The associated comment suggested that GCC keeps this extension enabled in C90/C++03 standard-conforming mode, but it actually does not, so rather than adding a check for C++ language version, this change simply removes the check for C language version. Reviewed By: rsmith Differential Revision: https://reviews.llvm.org/D91913 Added: Modified: clang/lib/Lex/TokenLexer.cpp clang/test/Preprocessor/macro_fn_comma_swallow2.c Removed: ################################################################################ diff --git a/clang/lib/Lex/TokenLexer.cpp b/clang/lib/Lex/TokenLexer.cpp index da5681aaf478..6e962dfa2c34 100644 --- a/clang/lib/Lex/TokenLexer.cpp +++ b/clang/lib/Lex/TokenLexer.cpp @@ -148,12 +148,11 @@ bool TokenLexer::MaybeRemoveCommaBeforeVaArgs( return false; // GCC removes the comma in the expansion of " ... , ## __VA_ARGS__ " if - // __VA_ARGS__ is empty, but not in strict C99 mode where there are no - // named arguments, where it remains. In all other modes, including C99 - // with GNU extensions, it is removed regardless of named arguments. + // __VA_ARGS__ is empty, but not in strict mode where there are no + // named arguments, where it remains. With GNU extensions, it is removed + // regardless of named arguments. // Microsoft also appears to support this extension, unofficially. - if (PP.getLangOpts().C99 && !PP.getLangOpts().GNUMode - && Macro->getNumParams() < 2) + if (!PP.getLangOpts().GNUMode && Macro->getNumParams() < 2) return false; // Is a comma available to be removed? diff --git a/clang/test/Preprocessor/macro_fn_comma_swallow2.c b/clang/test/Preprocessor/macro_fn_comma_swallow2.c index 93ab2b83664a..89ef8c0579c4 100644 --- a/clang/test/Preprocessor/macro_fn_comma_swallow2.c +++ b/clang/test/Preprocessor/macro_fn_comma_swallow2.c @@ -1,9 +1,12 @@ // Test the __VA_ARGS__ comma swallowing extensions of various compiler dialects. // RUN: %clang_cc1 -E %s | FileCheck -check-prefix=GCC -strict-whitespace %s +// RUN: %clang_cc1 -E -std=c90 %s | FileCheck -check-prefix=C99 -strict-whitespace %s // RUN: %clang_cc1 -E -std=c99 %s | FileCheck -check-prefix=C99 -strict-whitespace %s // RUN: %clang_cc1 -E -std=c11 %s | FileCheck -check-prefix=C99 -strict-whitespace %s // RUN: %clang_cc1 -E -x c++ %s | FileCheck -check-prefix=GCC -strict-whitespace %s +// RUN: %clang_cc1 -E -x c++ -std=c++03 %s | FileCheck -check-prefix=C99 -strict-whitespace %s +// RUN: %clang_cc1 -E -x c++ -std=c++11 %s | FileCheck -check-prefix=C99 -strict-whitespace %s // RUN: %clang_cc1 -E -std=gnu99 %s | FileCheck -check-prefix=GCC -strict-whitespace %s // RUN: %clang_cc1 -E -fms-compatibility %s | FileCheck -check-prefix=MS -strict-whitespace %s // RUN: %clang_cc1 -E -DNAMED %s | FileCheck -check-prefix=GCC -strict-whitespace %s _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
