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Add an `-Wundef-prefix=<arg1>,<arg2>...` option, which is similar to
`-Wundef`, but only give warnings for undefined macros with the given
prefixes.
Make `-Wundef` an alias of `-Wundef-prefix=""` so that when the two
options are given together, `-Wundef` takes precedence over
`-Wundef-prefix`, as all strings are prefixed by the empty string.
rdar://55684778
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D80748
Files:
clang/include/clang/Basic/DiagnosticGroups.td
clang/include/clang/Basic/DiagnosticLexKinds.td
clang/include/clang/Basic/DiagnosticOptions.h
clang/include/clang/Driver/Options.td
clang/lib/Frontend/CompilerInvocation.cpp
clang/lib/Lex/PPExpressions.cpp
clang/test/Preprocessor/warn-macro-undef-prefix.c
clang/test/Preprocessor/warn-macro-undef.c
Index: clang/test/Preprocessor/warn-macro-undef.c
===================================================================
--- /dev/null
+++ clang/test/Preprocessor/warn-macro-undef.c
@@ -0,0 +1,10 @@
+// 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
+
+#if B // expected-warning {{'B' is not defined, evaluates to 0}}
+#endif
Index: clang/test/Preprocessor/warn-macro-undef-prefix.c
===================================================================
--- /dev/null
+++ 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
Index: clang/lib/Lex/PPExpressions.cpp
===================================================================
--- clang/lib/Lex/PPExpressions.cpp
+++ 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);
Index: clang/lib/Frontend/CompilerInvocation.cpp
===================================================================
--- clang/lib/Frontend/CompilerInvocation.cpp
+++ 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<StringRef, 2> 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);
Index: clang/include/clang/Driver/Options.td
===================================================================
--- clang/include/clang/Driver/Options.td
+++ clang/include/clang/Driver/Options.td
@@ -465,6 +465,14 @@
def Wp_COMMA : CommaJoined<["-"], "Wp,">,
HelpText<"Pass the comma separated arguments in <arg> to the preprocessor">,
MetaVarName<"<arg>">, Group<Preprocessor_Group>;
+def Wundef_prefix_EQ : Joined<["-"], "Wundef-prefix=">, Group<W_value_Group>,
+ Flags<[CC1Option, CoreOption]>, MetaVarName<"<arg>">,
+ HelpText<"Enable warnings for undefined macros with a prefix in the comma separated list <arg>">;
+// 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<W_Group>, Flags<[CC1Option, CoreOption]>,
+ Alias<Wundef_prefix_EQ>,
+ HelpText<"Aliased to '-Wundef-prefix=\"\"', enable warnings for undefined macros">;
def Wwrite_strings : Flag<["-"], "Wwrite-strings">, Group<W_Group>, Flags<[CC1Option, HelpHidden]>;
def Wno_write_strings : Flag<["-"], "Wno-write-strings">, Group<W_Group>, Flags<[CC1Option, HelpHidden]>;
def W_Joined : Joined<["-"], "W">, Group<W_Group>, Flags<[CC1Option, CoreOption]>,
Index: clang/include/clang/Basic/DiagnosticOptions.h
===================================================================
--- clang/include/clang/Basic/DiagnosticOptions.h
+++ clang/include/clang/Basic/DiagnosticOptions.h
@@ -98,6 +98,10 @@
/// prefixes removed.
std::vector<std::string> Warnings;
+ /// The list of prefixes from -Wundef-prefix=... used to generate warnings
+ /// for undefined macros.
+ std::vector<std::string> UndefPrefixes;
+
/// The list of -R... options used to alter the diagnostic mappings, with the
/// prefixes removed.
std::vector<std::string> Remarks;
Index: clang/include/clang/Basic/DiagnosticLexKinds.td
===================================================================
--- clang/include/clang/Basic/DiagnosticLexKinds.td
+++ clang/include/clang/Basic/DiagnosticLexKinds.td
@@ -311,7 +311,7 @@
InGroup<DiagGroup<"unused-macros">>;
def warn_pp_undef_identifier : Warning<
"%0 is not defined, evaluates to 0">,
- InGroup<DiagGroup<"undef">>, DefaultIgnore;
+ InGroup<Undefined>, DefaultIgnore;
def warn_pp_ambiguous_macro : Warning<
"ambiguous expansion of macro %0">, InGroup<AmbiguousMacro>;
def note_pp_ambiguous_macro_chosen : Note<
Index: clang/include/clang/Basic/DiagnosticGroups.td
===================================================================
--- clang/include/clang/Basic/DiagnosticGroups.td
+++ 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">;
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