Clang requires lambda-capturing constexpr values when creating a named dependent type

[wthrowe]

Code is rejected as C++17 on clang-14.0.0 and current trunk. Godbolt: https://godbolt.org/z/YPq3sza68

template <typename T>
void f() {
    constexpr int x = 1;
    const auto test1 = []() { T y{x}; };  // error: variable 'x' cannot be implicitly captured in a lambda with no capture-default specified
    const auto test2 = []() { T{x}; };  // Accepted
    const auto test3 = []() { int y{x}; };  // Accepted
    const auto test4 = [&x]() { T y{x}; };  // Accepted, warns capture is unnecessary when `f<int>` is intantiated
}

[llvmbot]

@llvm/issue-subscribers-c-17

[llvmbot]

@llvm/issue-subscribers-clang-frontend