https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112267
Bug ID: 112267
Summary: "inline function constexpr used but never defined"
warning in SFINAE context
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: falemagn at gmail dot com
Target Milestone: ---
I am expecting no warnings from the following code snippets, especially because
SFINAE is being correctly triggered, and indeed clang doesn't provide one for
the specific case at hand, alas g++ does.
I am left wondering whether this is a bug or a "overreaction". The warning
itself cannot be turned off with a pragma.
#if defined(__clang__)
_Pragma("GCC diagnostic ignored \"-Wundefined-inline\"");
#endif
#define DEFINE_FUNC 0
constexpr bool func()
#if DEFINE_FUNC
{
return true;
}
#else
;
#endif
template <int Dummy = 0, bool = func()>
constexpr bool is_defined(int) {
return true;
}
template <int Dummy = 0>
constexpr bool is_defined(double) {
return false;
}
int a = is_defined(0);
See it working on Compiler Explorer: https://godbolt.org/z/dvTKdGfbv
