diff --git a/clang/include/clang/Basic/DiagnosticGroups.td b/clang/include/clang/Basic/DiagnosticGroups.td --- a/clang/include/clang/Basic/DiagnosticGroups.td +++ b/clang/include/clang/Basic/DiagnosticGroups.td @@ -104,6 +104,8 @@ def FrameAddress : DiagGroup<"frame-address">; def DoublePromotion : DiagGroup<"double-promotion">; def EnumTooLarge : DiagGroup<"enum-too-large">; +def Undefined : DiagGroup<"undef">; +def UndefinedPrefix : DiagGroup<"undef-prefix", [Undefined]>; def UnsupportedNan : DiagGroup<"unsupported-nan">; def UnsupportedAbs : DiagGroup<"unsupported-abs">; def UnsupportedCB : DiagGroup<"unsupported-cb">; diff --git a/clang/include/clang/Basic/DiagnosticLexKinds.td b/clang/include/clang/Basic/DiagnosticLexKinds.td --- a/clang/include/clang/Basic/DiagnosticLexKinds.td +++ b/clang/include/clang/Basic/DiagnosticLexKinds.td @@ -311,7 +311,7 @@ InGroup>; def warn_pp_undef_identifier : Warning< "%0 is not defined, evaluates to 0">, - InGroup>, DefaultIgnore; + InGroup, DefaultIgnore; def warn_pp_ambiguous_macro : Warning< "ambiguous expansion of macro %0">, InGroup; def note_pp_ambiguous_macro_chosen : Note< diff --git a/clang/include/clang/Basic/DiagnosticOptions.h b/clang/include/clang/Basic/DiagnosticOptions.h --- a/clang/include/clang/Basic/DiagnosticOptions.h +++ b/clang/include/clang/Basic/DiagnosticOptions.h @@ -98,6 +98,10 @@ /// prefixes removed. std::vector Warnings; + /// The list of prefixes from -Wundef-prefix=... used to generate warnings + /// for undefined macros. + std::vector UndefPrefixes; + /// The list of -R... options used to alter the diagnostic mappings, with the /// prefixes removed. std::vector Remarks; diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td --- a/clang/include/clang/Driver/Options.td +++ b/clang/include/clang/Driver/Options.td @@ -465,6 +465,14 @@ def Wp_COMMA : CommaJoined<["-"], "Wp,">, HelpText<"Pass the comma separated arguments in to the preprocessor">, MetaVarName<"">, Group; +def Wundef_prefix_EQ : Joined<["-"], "Wundef-prefix=">, Group, + Flags<[CC1Option, CoreOption]>, MetaVarName<"">, + HelpText<"Enable warnings for undefined macros with a prefix in the comma separated list ">; +// Rely on the implementation that a Flag alias for a Joined option is provided a default argument +// of an empty string (""). So we have -Wundef => -Wundef-prefix="" +def Wundef: Flag<["-"], "Wundef">, Group, Flags<[CC1Option, CoreOption]>, + Alias, + HelpText<"Aliased to '-Wundef-prefix=\"\"', enable warnings for undefined macros">; def Wwrite_strings : Flag<["-"], "Wwrite-strings">, Group, Flags<[CC1Option, HelpHidden]>; def Wno_write_strings : Flag<["-"], "Wno-write-strings">, Group, Flags<[CC1Option, HelpHidden]>; def W_Joined : Joined<["-"], "W">, Group, Flags<[CC1Option, CoreOption]>, diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp --- a/clang/lib/Frontend/CompilerInvocation.cpp +++ b/clang/lib/Frontend/CompilerInvocation.cpp @@ -1820,6 +1820,16 @@ } Opts.MessageLength = getLastArgIntValue(Args, OPT_fmessage_length_EQ, 0, Diags); + + for (const auto *A : Args.filtered(OPT_Wundef_prefix_EQ)) { + SmallVector Prefixes; + // Keep empty strings to allow '-Wundef' (aliased to '-Wundef-prefix=""') + // to generate diagnostics for all undefined macros. + StringRef{A->getValue()}.split(Prefixes, ","); + for (const auto &P : Prefixes) + Opts.UndefPrefixes.push_back(P.str()); + } + addDiagnosticArgs(Args, OPT_W_Group, OPT_W_value_Group, Opts.Warnings); addDiagnosticArgs(Args, OPT_R_Group, OPT_R_value_Group, Opts.Remarks); diff --git a/clang/lib/Lex/PPExpressions.cpp b/clang/lib/Lex/PPExpressions.cpp --- a/clang/lib/Lex/PPExpressions.cpp +++ b/clang/lib/Lex/PPExpressions.cpp @@ -251,8 +251,21 @@ // If this identifier isn't 'defined' or one of the special // 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; + if (ValueLive) { + const auto &UndefPrefixes = + PP.getDiagnostics().getDiagnosticOptions().UndefPrefixes; + const auto &IdentifierName = II->getName(); + // Check whether UndefPrefixes is empty for standalone + // "-Werror=undef" to work. + // "-Werror=undef" implies "-Wundef" but does not add an empty + // string to UndefPrefixes as an explicit "-Wundef" does. + if (UndefPrefixes.empty() || + llvm::any_of(UndefPrefixes, + [&IdentifierName](const auto &Prefix) { + return IdentifierName.startswith(Prefix); + })) + PP.Diag(PeekTok, diag::warn_pp_undef_identifier) << II; + } Result.Val = 0; Result.Val.setIsUnsigned(false); // "0" is signed intmax_t 0. Result.setIdentifier(II); diff --git a/clang/test/Preprocessor/warn-macro-undef-prefix.c b/clang/test/Preprocessor/warn-macro-undef-prefix.c new file mode 100644 --- /dev/null +++ b/clang/test/Preprocessor/warn-macro-undef-prefix.c @@ -0,0 +1,23 @@ +// RUN: %clang_cc1 %s -Eonly -Wundef-prefix=A,BC -verify + +extern int x; + +#if A // expected-warning {{'A' is not defined, evaluates to 0}} +#endif + +#if A1 // expected-warning {{'A1' is not defined, evaluates to 0}} +#endif + +#if B // no warning +#endif + +#define BC 0 +#if BC // no warning +#endif + +#undef BC +#if BC // expected-warning {{'BC' is not defined, evaluates to 0}} +#endif + +#if BC1 // expected-warning {{'BC1' is not defined, evaluates to 0}} +#endif diff --git a/clang/test/Preprocessor/warn-macro-undef.c b/clang/test/Preprocessor/warn-macro-undef.c new file mode 100644 --- /dev/null +++ b/clang/test/Preprocessor/warn-macro-undef.c @@ -0,0 +1,17 @@ +// RUN: %clang_cc1 %s -Eonly -Wundef -verify +// RUN: %clang_cc1 %s -Eonly -Wundef -Wundef-prefix=A -verify + +extern int x; + +#if A // expected-warning {{'A' is not defined, evaluates to 0}} +#endif + +#pragma clang diagnostic ignored "-Wundef" + +#if B // no warning +#endif + +#pragma clang diagnostic warning "-Wundef" + +#if B // expected-warning {{'B' is not defined, evaluates to 0}} +#endif