Author: isuckatcs Date: 2025-03-02T19:00:27+01:00 New Revision: 3a11d5a8dfb6c95a5ba0c6b4463e15494005a369
URL: https://github.com/llvm/llvm-project/commit/3a11d5a8dfb6c95a5ba0c6b4463e15494005a369 DIFF: https://github.com/llvm/llvm-project/commit/3a11d5a8dfb6c95a5ba0c6b4463e15494005a369.diff LOG: [clang][diagnostics] add `-Wundef-true` warning option (#128265) New option `-Wundef-true` added and enabled by default to warn when `true` is used in the C preprocessor without being defined before C23. Added: clang/test/Preprocessor/warn-macro-undef-true.c Modified: clang/docs/ReleaseNotes.rst clang/include/clang/Basic/DiagnosticGroups.td clang/include/clang/Basic/DiagnosticLexKinds.td clang/lib/Lex/PPExpressions.cpp Removed: ################################################################################ diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst index c97bbc372fcb7..d2fc1ce07dd79 100644 --- a/clang/docs/ReleaseNotes.rst +++ b/clang/docs/ReleaseNotes.rst @@ -114,6 +114,8 @@ Non-comprehensive list of changes in this release New Compiler Flags ------------------ +- New option ``-Wundef-true`` added and enabled by default to warn when `true` is used in the C preprocessor without being defined before C23. + - New option ``-fprofile-continuous`` added to enable continuous profile syncing to file (#GH124353, `docs <https://clang.llvm.org/docs/UsersManual.html#cmdoption-fprofile-continuous>`_). The feature has `existed <https://clang.llvm.org/docs/SourceBasedCodeCoverage.html#running-the-instrumented-program>`_) for a while and this is just a user facing option. diff --git a/clang/include/clang/Basic/DiagnosticGroups.td b/clang/include/clang/Basic/DiagnosticGroups.td index 77520447b813d..fac80fb4009aa 100644 --- a/clang/include/clang/Basic/DiagnosticGroups.td +++ b/clang/include/clang/Basic/DiagnosticGroups.td @@ -791,6 +791,8 @@ def ReservedIdAsMacroAlias : DiagGroup<"reserved-id-macro", [ReservedIdAsMacro]> def ReservedAttributeIdentifier : DiagGroup<"reserved-attribute-identifier">; def RestrictExpansionMacro : DiagGroup<"restrict-expansion">; def FinalMacro : DiagGroup<"final-macro">; +def UndefinedTrueIdentifier : DiagGroup<"undef-true">; +def UndefinedIdentifier : DiagGroup<"undef", [UndefinedTrueIdentifier]>; // Just silence warnings about -Wstrict-aliasing for now. def : DiagGroup<"strict-aliasing=0">; diff --git a/clang/include/clang/Basic/DiagnosticLexKinds.td b/clang/include/clang/Basic/DiagnosticLexKinds.td index 2b1cc81677b08..8daf3602450f0 100644 --- a/clang/include/clang/Basic/DiagnosticLexKinds.td +++ b/clang/include/clang/Basic/DiagnosticLexKinds.td @@ -392,7 +392,10 @@ def pp_macro_not_used : Warning<"macro is not used">, DefaultIgnore, InGroup<DiagGroup<"unused-macros">>; def warn_pp_undef_identifier : Warning< "%0 is not defined, evaluates to 0">, - InGroup<DiagGroup<"undef">>, DefaultIgnore; + InGroup<UndefinedIdentifier>, DefaultIgnore; +def warn_pp_undef_true_identifier : Warning< + "'true' is not defined, evaluates to 0">, + InGroup<UndefinedTrueIdentifier>; def warn_pp_undef_prefix : Warning< "%0 is not defined, evaluates to 0">, InGroup<DiagGroup<"undef-prefix">>, DefaultIgnore; diff --git a/clang/lib/Lex/PPExpressions.cpp b/clang/lib/Lex/PPExpressions.cpp index a3b1384f0fa1d..b031571907441 100644 --- a/clang/lib/Lex/PPExpressions.cpp +++ b/clang/lib/Lex/PPExpressions.cpp @@ -257,12 +257,14 @@ static bool EvaluateValue(PPValue &Result, Token &PeekTok, DefinedTracker &DT, // preprocessor keywords and it wasn't macro expanded, it turns // into a simple 0 if (ValueLive) { - PP.Diag(PeekTok, diag::warn_pp_undef_identifier) << II; + unsigned DiagID = II->getName() == "true" + ? diag::warn_pp_undef_true_identifier + : diag::warn_pp_undef_identifier; + PP.Diag(PeekTok, DiagID) << II; const DiagnosticsEngine &DiagEngine = PP.getDiagnostics(); // If 'Wundef' is enabled, do not emit 'undef-prefix' diagnostics. - if (DiagEngine.isIgnored(diag::warn_pp_undef_identifier, - PeekTok.getLocation())) { + if (DiagEngine.isIgnored(DiagID, PeekTok.getLocation())) { const std::vector<std::string> UndefPrefixes = DiagEngine.getDiagnosticOptions().UndefPrefixes; const StringRef IdentifierName = II->getName(); diff --git a/clang/test/Preprocessor/warn-macro-undef-true.c b/clang/test/Preprocessor/warn-macro-undef-true.c new file mode 100644 index 0000000000000..9a64d577a96ed --- /dev/null +++ b/clang/test/Preprocessor/warn-macro-undef-true.c @@ -0,0 +1,78 @@ +// RUN: %clang_cc1 %s -Eonly -std=c89 -verify=undef-true +// RUN: %clang_cc1 %s -Eonly -std=c99 -verify=undef-true +// RUN: %clang_cc1 %s -Eonly -std=c11 -verify=undef-true +// RUN: %clang_cc1 %s -Eonly -std=c17 -verify=undef-true +// RUN: %clang_cc1 %s -Eonly -std=c23 -verify=undef-true + +#if __STDC_VERSION__ >= 202311L +/* undef-true-no-diagnostics */ +#endif + +#define FOO true +#if FOO /* #1 */ +#endif +#if __STDC_VERSION__ < 202311L +/* undef-true-warning@#1 {{'true' is not defined, evaluates to 0}} */ +#endif + +#if true /* #2 */ +#endif +#if __STDC_VERSION__ < 202311L +/* undef-true-warning@#2 {{'true' is not defined, evaluates to 0}} */ +#endif + +#if false || true /* #3 */ +#endif +#if __STDC_VERSION__ < 202311L +/* undef-true-warning@#3 {{'true' is not defined, evaluates to 0}} */ +#endif + +#define true 1 + +#define FOO true +#if FOO +#endif + +#if true +#endif + +#if false || true +#endif + +#undef true + +#define FOO true +#if FOO /* #4 */ +#endif +#if __STDC_VERSION__ < 202311L +/* undef-true-warning@#4 {{'true' is not defined, evaluates to 0}} */ +#endif + +#if true /* #5 */ +#endif +#if __STDC_VERSION__ < 202311L +/* undef-true-warning@#5 {{'true' is not defined, evaluates to 0}} */ +#endif + +#if false || true /* #6 */ +#endif +#if __STDC_VERSION__ < 202311L +/* undef-true-warning@#6 {{'true' is not defined, evaluates to 0}} */ +#endif + +#define true true +#if true /* #7 */ +#endif +#if __STDC_VERSION__ < 202311L +/* undef-true-warning@#7 {{'true' is not defined, evaluates to 0}} */ +#endif +#undef true + +/* Test that #pragma-enabled 'Wundef' can override 'Wundef-true' */ +#pragma clang diagnostic warning "-Wundef" +#if true /* #8 */ +#endif +#pragma clang diagnostic ignored "-Wundef" +#if __STDC_VERSION__ < 202311L +/* undef-true-warning@#8 {{'true' is not defined, evaluates to 0}} */ +#endif _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
