Clang does not see class member in a 'requires'.

[EdvinVikstrom]

Tested with clang-trunk.
Here's the code:

template<typename T>
class Test {

public:

    static constexpr int val = 16;
    
    constexpr Test()
        requires (val == 16);
};

template<typename T>
constexpr Test<T>::Test() // error: out-of-line definition of 'Test<T>' does not match any declaration in 'Test<T>'
    requires (val == 16) // error: use of undeclared identifier 'val'
{
}

int main()
{
    Test<int> test();
    return 0;
}

I tested with GCC and it gives no errors.
Replacing val == 16 with Test<T>::val == 16 removes the 'undeclared identifier...' error but 'out-of-line...' error remains.
With no template parameters the code compiles if you write Test::val == 16.

[llvmbot]

@llvm/issue-subscribers-clang-frontend

[s2s-k]

I think this code is also part of the problem.

MSVC: https://godbolt.org/z/a5c1bEWdx
GCC: https://godbolt.org/z/xKzxxnj8x
Clang: https://godbolt.org/z/vo1axTdqb

error: out-of-line definition of 'operator[]' from class 'CStore<Type>' without definition

[llvmbot]

@llvm/issue-subscribers-c-20

[ilya-biryukov]

I'm assigning to myself for visibility, even though @luken-google was about to work on this.
(Luke is not part of the LLVM GH Project yet)

[luken-google]

Fix out for review at https://reviews.llvm.org/D132503