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| author | Marek Polacek <polacek@redhat.com> | 2022-11-01 11:49:03 -0400 |
|---|---|---|
| committer | Marek Polacek <polacek@redhat.com> | 2022-11-15 17:44:13 -0500 |
| commit | ed1797ddf8285f59a50d9c883beb97705279d980 (patch) | |
| tree | 45f3b83dded8a3da2c41821a18ce8cdd6604dd05 | |
| parent | c717a92dd89321eeb74aaa3daeb32354ac588d20 (diff) | |
| download | gcc-ed1797ddf8285f59a50d9c883beb97705279d980.zip gcc-ed1797ddf8285f59a50d9c883beb97705279d980.tar.gz gcc-ed1797ddf8285f59a50d9c883beb97705279d980.tar.bz2 | |
c++: Disable -Wignored-qualifiers for template args [PR107492]
It seems wrong to issue a -Wignored-qualifiers warning for code like:
static_assert(!is_same_v<void(*)(), const void(*)()>);
because there the qualifier matters. Likewise in template
specialization:
template<typename T> struct S { };
template<> struct S<void(*)()> { };
template<> struct S<const void(*)()> { }; // OK, not a redefinition
And likewise in other type-id contexts such as trailing-return-type:
auto g() -> const void (*)();
This patch limits the warning to the function declaration context only.
PR c++/107492
gcc/cp/ChangeLog:
* decl.cc (grokdeclarator): Only emit a -Wignored-qualifiers warning
when funcdecl_p.
gcc/testsuite/ChangeLog:
* g++.dg/warn/Wignored-qualifiers3.C: New test.
| -rw-r--r-- | gcc/cp/decl.cc | 6 | ||||
| -rw-r--r-- | gcc/testsuite/g++.dg/warn/Wignored-qualifiers3.C | 24 |
2 files changed, 29 insertions, 1 deletions
diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc index c83fdac..0234919 100644 --- a/gcc/cp/decl.cc +++ b/gcc/cp/decl.cc @@ -13038,7 +13038,11 @@ grokdeclarator (const cp_declarator *declarator, if (type_quals != TYPE_UNQUALIFIED) { - if (SCALAR_TYPE_P (type) || VOID_TYPE_P (type)) + /* It's wrong, for instance, to issue a -Wignored-qualifiers + warning for + static_assert(!is_same_v<void(*)(), const void(*)()>); + because there the qualifier matters. */ + if (funcdecl_p && (SCALAR_TYPE_P (type) || VOID_TYPE_P (type))) warning_at (typespec_loc, OPT_Wignored_qualifiers, "type " "qualifiers ignored on function return type"); /* [dcl.fct] "A volatile-qualified return type is diff --git a/gcc/testsuite/g++.dg/warn/Wignored-qualifiers3.C b/gcc/testsuite/g++.dg/warn/Wignored-qualifiers3.C new file mode 100644 index 0000000..dedb38f --- /dev/null +++ b/gcc/testsuite/g++.dg/warn/Wignored-qualifiers3.C @@ -0,0 +1,24 @@ +// PR c++/107492 +// { dg-do compile { target c++14 } } +// { dg-additional-options "-Wignored-qualifiers" } + +// Here the 'const' matters, so don't warn. +template<typename T> struct S { }; +template<> struct S<void(*)()> { }; +template<> struct S<const void(*)()> { }; // { dg-bogus "ignored" } + +template<typename T, typename U> constexpr bool is_same_v = false; +template<typename T> constexpr bool is_same_v<T, T> = true; + +static_assert( ! is_same_v< void(*)(), const void(*)() >, ""); // { dg-bogus "ignored" } + +// Here the 'const' matters as well -> don't warn. +auto g() -> const void (*)(); // { dg-bogus "ignored" } +auto g() -> const void (*)() { return nullptr; } // { dg-bogus "ignored" } + +// Here as well. +const void (*h)() = static_cast<const void (*)()>(h); // { dg-bogus "ignored" } + +// But let's keep the warning here. +const void f(); // { dg-warning "ignored" } +const void f() { } // { dg-warning "ignored" } |