Clang ignores a constraint in a partial specialization of a class template

[Dann239]

I'm trying to create a specialization of the Foo class template that only accepts specializations of the Bar class template as a template argument. However, clang ignores my IsBar<T> constraint and accepts int as a template argument.

template<typename>
struct Foo;

template<typename>
struct Bar {};

template<typename T>
concept IsBar = requires (T t) { [] <typename U> (Bar<U>& c) {} (t); };

template<IsBar T>
struct Foo<T> {
    static void test() {}
};

int main() {
    Foo<Bar<int>>::test(); // OK

    // static_assert(!IsBar<int>);

    // the following line compiles
    // unless i uncomment the static_assert:
    Foo<int>::test(); // this should not compile
}

static_assert'ing !IsBar<int> seems to make it correctly reject int

[llvmbot]

@llvm/issue-subscribers-clang-frontend

[usx95]

This looks more specific to lambda in the simple-requirement

template<typename>
struct Foo;

template<typename T>
concept Add = requires(T t) {
    [](T t) { t++; }(t);
};

template<Add T>
struct Foo<T> {
    static void test() {}
};

int main() {
    Foo<int>::test(); // this should not compile
}

Original code as well as the above gives an assertion failure. It tries to evaluate the dependent lambda without instantiating it properly.
https://godbolt.org/z/fWqbj9Poz

[zyn0217]

This should have been fixed by #83997.
I'll close the PR once the patch gets on godbolt.

[zyn0217]

And here it is: https://godbolt.org/z/474vsh8MP
Closing.