CTAD: crashes on clang::Expr::EvaluateAsConstantExpr

[hokein]

clang current crashes on the following code.

template <typename>
constexpr bool C = true;
template<class T1, typename T2>
struct Foo {
  template<class V> requires C<V> // Index of V in the Foo deduction guide is 2
  Foo(V, T1);
};

template<class T3>
using AFoo = Foo<T3, T3>;
AFoo afoo{0, 1};

The index of template parameter occurrence V in the require-clause of the synthesized AFoo deduction guide auto (T3, V) -> Foo<T3, T3>is wrong (2), it should be 1. We miss this case at https://github.com/llvm/llvm-project/blob/main/clang/lib/Sema/SemaTemplate.cpp#L2857-L2858.

[llvmbot]

@llvm/issue-subscribers-clang-frontend

Author: Haojian Wu (hokein)

clang current crashes on the following code.

template <typename>
constexpr bool C = true;
template<class T1, typename T2>
struct Foo {
  template<class V> requires C<V> // Index of V in the Foo deduction guide is 2
  Foo(V, T1);
};

template<class T3>
using AFoo = Foo<T3, T3>;
AFoo afoo{0, 1};

The index of template parameter occurrence V in the require-clause of the synthesized AFoo deduction guide auto (T3, V) -> Foo<T3, T3>is wrong (2), it should be 1. We miss this case at https://github.com/llvm/llvm-project/blob/main/clang/lib/Sema/SemaTemplate.cpp#L2857-L2858.

[shafik]

Confirmed: https://godbolt.org/z/KcfEqd69v