https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63872
Bug ID: 63872
Summary: -Wunused-local-typedefs warns incorrectly on a typedef
that's referenced from a template
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: thakis at chromium dot org
$ cat test2.cc
typedef char YesType;
struct NoType { YesType dummy[2]; };
template <typename T>
struct ShouldAbortOnSelfReset {
template <typename U>
static NoType Test(const typename U::AllowSelfReset*);
template <typename U>
static YesType Test(...);
static const bool value = sizeof(Test<T>(0)) == sizeof(YesType);
};
template<class T>
struct Foo {
void reset() {
ShouldAbortOnSelfReset<T>::value;
}
};
void f() {
struct NoOpDeleter {
typedef void AllowSelfReset;
inline void operator()(int*) {}
};
Foo<NoOpDeleter> f;
f.reset();
}
$ ~/gcc482prefix/bin/gcc -c test2.cc -std=c++11 -Wall
test2.cc: In function ‘void f()’:
test2.cc:24:18: warning: typedef ‘f()::NoOpDeleter::AllowSelfReset’ locally
defined but not used [-Wunused-local-typedefs]
typedef void AllowSelfReset;
^
test2.cc: In instantiation of ‘void Foo<T>::reset() [with T =
f()::NoOpDeleter]’:
test2.cc:29:11: required from here
Warning on this is very dangerous, since removing the typedef will change the
meaning of the code but it's still going to compile.
This is with 4.8.2, but it also happens in gcc 4.9.
