From 5c8c9905c2496a38a17f1b2a180601e790e45db9 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Lubo=C5=A1=20Lu=C5=88=C3=A1k?= Date: Sun, 2 Feb 2020 12:15:40 +0100 Subject: [PATCH] make sure to not warn about unused macros from -D If a PCH is used for compilation, SourceManager::isInMainFile() returns true even for the "" predefines area. Using -D only for the TU compilation may trigger -Wunused-macros for it. It is admitedly a bit fishy to set a macro only for a TU and not for the PCH, but this works fine if the PCH does not use the macro (I couldn't find a statement on this for Clang, but GCC explicitly allows this in the docs). Differential Revision: https://reviews.llvm.org/D73846 --- clang/lib/Lex/PPDirectives.cpp | 4 +++- clang/test/PCH/cli-macro.c | 12 ++++++++++++ 2 files changed, 15 insertions(+), 1 deletion(-) create mode 100644 clang/test/PCH/cli-macro.c diff --git a/clang/lib/Lex/PPDirectives.cpp b/clang/lib/Lex/PPDirectives.cpp index d6b6f56..d8041ae 100644 --- a/clang/lib/Lex/PPDirectives.cpp +++ b/clang/lib/Lex/PPDirectives.cpp @@ -2802,7 +2802,9 @@ void Preprocessor::HandleDefineDirective( // warn-because-unused-macro set. If it gets used it will be removed from set. if (getSourceManager().isInMainFile(MI->getDefinitionLoc()) && !Diags->isIgnored(diag::pp_macro_not_used, MI->getDefinitionLoc()) && - !MacroExpansionInDirectivesOverride) { + !MacroExpansionInDirectivesOverride && + getSourceManager().getFileID(MI->getDefinitionLoc()) != + getPredefinesFileID()) { MI->setIsWarnIfUnused(true); WarnUnusedMacroLocs.insert(MI->getDefinitionLoc()); } diff --git a/clang/test/PCH/cli-macro.c b/clang/test/PCH/cli-macro.c new file mode 100644 index 0000000..bae8cc3 --- /dev/null +++ b/clang/test/PCH/cli-macro.c @@ -0,0 +1,12 @@ +// Test this without pch. +// RUN: %clang_cc1 -Wunused-macros -Dunused=1 -fsyntax-only -verify %s + +// Test with pch. +// RUN: %clang_cc1 -Wunused-macros -emit-pch -o %t %s +// RUN: %clang_cc1 -Wunused-macros -Dunused=1 -include-pch %t -fsyntax-only -verify %s + +// expected-no-diagnostics + +// -Dunused=1 is intentionally not set for the pch. +// There still should be no unused warning for a macro from the command line. + -- 2.7.4