http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46643
--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> 2010-11-24
18:37:53 UTC ---
It looks as though 4.4 had a problem with templates too, here S<T> is a POD but
there's no warning for foo::bar
template<typename> struct S { };
template<typename T>
class foo {
public:
S<T> bar() __attribute__((warn_unused_result));
int baz() __attribute__((warn_unused_result));
};
template<typename T> inline
S<T> foo<T>::bar() { return S<T>(); }
template<typename T> inline
int foo<T>::baz() { return 0; }
int main(void) {
foo<int> b;
b.bar();
b.baz();
return 0;
}
That seems to be fixed in 4.5 and 4.6
Not quite as simple as non-POD either, here S is a non-POD but there's a
warning:
struct S { S() { } };
template<typename T>
class foo {
public:
S bar() __attribute__((warn_unused_result));
};
template<typename T> inline
S foo<T>::bar() { return S(); }
int main(void) {
foo<int> b;
b.bar();
}
Change the user-declared constructor to a user-declared destructor and the
warning is missing
