https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83417
David Friberg <davveston at gmail dot com> changed:
What |Removed |Added
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CC| |davveston at gmail dot com
--- Comment #3 from David Friberg <davveston at gmail dot com> ---
The same holds for the case of function pointers.
Given the following function:
void f(int) {}
Both examples (A) and (B) below are well-formed, as per [temp.deduct.type]/13
(and for (B): also as per [temp.arg.nontype]/1).
// Example (A)
template <auto>
struct A;
template <typename T, void (*fp)(T)>
struct A<fp> { };
A<f> a{}; // #1: OK
// Example (B)
template <auto>
struct B;
template <typename T, auto (*fp)(T)>
struct B<fp> { };
B<f> b{}; // #2: Rejected (type deduction failure in partial specialization)
Clang accepts both, whereas GCC (trunk/any version I've tried that supports
C++17) rejects example (B), as #2 is resolved to the primary (non-defined)
class template after failing to deduce the dependent 'T' from 'auto (*fp)(T)'
in the partial specialization, given the argument 'f' to the latter (non-type)
template parameter.
