https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79001
Bug ID: 79001
Summary: spurious "defined but not used" warning with explicit
instantiation
Product: gcc
Version: 6.3.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: jens.maurer at gmx dot net
Target Milestone: ---
The following testcase gives a "defined but not used" warning for "f", but not
for "g". I agree that "f" cannot be used outside of the translation unit (due
to the use of a type from an anonymous namespace), but neither can "g".
Plus, if someone does use explicit instantiations on a class, it does not seem
helpful to produce "unused function" warnings for functions generated from an
explicit instantiation on a class in the first place, because the class (maybe
from a library) might have a lot more member functions than actually in use in
any given file.
template <class T>
class C {
void f();
void g() { }
};
template<class T>
void C<T>::f() { }
namespace {
struct X { };
}
template class C<X>;
V$ gcc -Wunused-function -c x.cc
x.cc:9:6: warning: ‘void C<T>::f() [with T = {anonymous}::X]’ defined but not
used [-Wunused-function]
void C<T>::f() { }
^~~~
