https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98614
Bug ID: 98614
Summary: Copy ctor/assign cannot be defaulted in specialization
by concept
Product: gcc
Version: 10.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: iDingDong at outlook dot com
Target Milestone: ---
GCC 10.2 rejects the following piece of code:
//---
#include <concepts>
template <typename T> struct A {
A(A<T> const&) = default;
};
template <std::same_as<int> T> struct A<T> {
A(A<T> const&) = default;
};
//---
The error message:
> <source>:8:19: error: 'A<T>::A(const A<T>&)' cannot be defaulted
This can be reproduced by the compiler explorer: https://godbolt.org/z/1v6nPv
I can locally reproduce this with:
> g++ -std=c++20 test.cpp
This error only occurs when trying to default a copy constructor in a partial
specialization involving concept. The workaround is to omit the `<T>` in the
constructor/assignment's argument declarator.
PS: move constructor/assignment seems unaffected.
