Defining constrained member function out of line is rejected

[llvmbot]

Bugzilla Link	48020
Version	trunk
OS	Windows NT
Reporter	LLVM Bugzilla Contributor
CC	@CaseyCarter,@zygoloid

Extended Description

From StackOverflow (https://stackoverflow.com/q/64601583/2069064):

template <typename> concept C = true;

template <typename T>
struct Foo { };

template<typename T>
    requires C<T>
struct Foo<T> {
    static void bar();
};

template<typename T>
    requires C<T>
void Foo<T>::bar() { }

int main() {
    Foo<int>::bar();
}

clang 11 rejects this program with:

<source>:13:10: error: requires clause differs in template redeclaration
requires C<T>
         ^
<source>:3:1: note: previous template declaration is here
template <typename T>
^

[llvmbot]

@llvm/issue-subscribers-clang-frontend

[usx95]

Duplicate of #49620 (more activity).