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Clang's `-Wvexing-parse` is enabled by default
<https://godbolt.org/z/5Ec4f69sv>. When the vexing statement was _intended_ to
be interpreted as a function that takes zero arguments, the function's
declaration can be rewritten as `T foo(void);` to silence `-Wvexing-parse`.
This workaround seems to upset `clang-tidy`.
Given my own lack of understanding of the corners of C++ parsing, I'm... not
entirely confident that this patch catches everything && has no unintended
side-effects. The bits that `-Wvexing-parse` depends upon are stored within
`DeclaratorChunk::FunctionTypeInfo`s, which seem to only exist during AST
formation, so it's not clear to me how to directly get at that information from
clang-tidy.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D126735
Files:
clang-tools-extra/clang-tidy/modernize/RedundantVoidArgCheck.cpp
clang-tools-extra/test/clang-tidy/checkers/modernize-redundant-void-arg.cpp
Index:
clang-tools-extra/test/clang-tidy/checkers/modernize-redundant-void-arg.cpp
===================================================================
--- clang-tools-extra/test/clang-tidy/checkers/modernize-redundant-void-arg.cpp
+++ clang-tools-extra/test/clang-tidy/checkers/modernize-redundant-void-arg.cpp
@@ -592,3 +592,9 @@
(void)a;
}
#undef return_t
+
+// Explicitly specifying `(void)` is a way to sidestep -Wvexing-parse, so we
+// should not warn about it here.
+void most_vexing_parse() {
+ int foo(void);
+}
Index: clang-tools-extra/clang-tidy/modernize/RedundantVoidArgCheck.cpp
===================================================================
--- clang-tools-extra/clang-tidy/modernize/RedundantVoidArgCheck.cpp
+++ clang-tools-extra/clang-tidy/modernize/RedundantVoidArgCheck.cpp
@@ -109,9 +109,13 @@
}
removeVoidArgumentTokens(Result, SourceRange(Start, End),
"function definition");
- } else
+ } else if (!Function->getLexicalDeclContext()->isFunctionOrMethod()) {
+ // Only do this if our decl context is outside of a function or method;
+ // otherwise, the user may have explicitly written `(void)` to avoid Most
+ // Vexing Parse warnings.
removeVoidArgumentTokens(Result, SourceRange(Start, End),
"function declaration");
+ }
}
bool isMacroIdentifier(const IdentifierTable &Idents, const Token &ProtoToken)
{
Index: clang-tools-extra/test/clang-tidy/checkers/modernize-redundant-void-arg.cpp
===================================================================
--- clang-tools-extra/test/clang-tidy/checkers/modernize-redundant-void-arg.cpp
+++ clang-tools-extra/test/clang-tidy/checkers/modernize-redundant-void-arg.cpp
@@ -592,3 +592,9 @@
(void)a;
}
#undef return_t
+
+// Explicitly specifying `(void)` is a way to sidestep -Wvexing-parse, so we
+// should not warn about it here.
+void most_vexing_parse() {
+ int foo(void);
+}
Index: clang-tools-extra/clang-tidy/modernize/RedundantVoidArgCheck.cpp
===================================================================
--- clang-tools-extra/clang-tidy/modernize/RedundantVoidArgCheck.cpp
+++ clang-tools-extra/clang-tidy/modernize/RedundantVoidArgCheck.cpp
@@ -109,9 +109,13 @@
}
removeVoidArgumentTokens(Result, SourceRange(Start, End),
"function definition");
- } else
+ } else if (!Function->getLexicalDeclContext()->isFunctionOrMethod()) {
+ // Only do this if our decl context is outside of a function or method;
+ // otherwise, the user may have explicitly written `(void)` to avoid Most
+ // Vexing Parse warnings.
removeVoidArgumentTokens(Result, SourceRange(Start, End),
"function declaration");
+ }
}
bool isMacroIdentifier(const IdentifierTable &Idents, const Token &ProtoToken) {
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