https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97376
Bug ID: 97376
Summary: Function type to function pointer type adjustment for
non-type template paramter does not work when using
decltype(auto)
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: anders.granlund.0 at gmail dot com
Target Milestone: ---
Consider the following program:
#include <iostream>
#include <type_traits>
template<decltype(auto) X>
void f1()
{
}
template<void X()>
void f2()
{
}
void ff()
{
}
int main()
{
f1<ff>();
f2<ff>();
}
When compiling it with -std=c++17 -pedantic-errors it gives a compilation
error complaining that the non-type parameter X of the template f1 has type
void () and that this is not a valid type for a non-type template paramter.
The expected behaviour is that the type of X in f1 should instead be
ajusted to void (*)() . This is what happens in template f2 .
Note that clang gives the expected behaviour (no compilation errors). Compiler
explorer link comparing clang and gcc:
https://godbolt.org/z/PGbrYE
