out of line definition should reject template parameter with lambda of unevaluated context

[nickhuang99]

Bugzilla Link	52074
Version	trunk
OS	Linux
CC	@dwblaikie,@zygoloid

Extended Description

The following code should be rejected as no matching declaration found as GCC/MSVC++ does. clang-13 incorrectly passes without considering that two lambda expressions are never considered as equivalent. [temp.over.link#5.sentence-4]

template
struct A{
void spam(decltype([]{}) );
};

template
void A::spam(decltype([]{}))
{}

struct A{
template
void spam(decltype([]{}) );
};

template
void A::spam(decltype([]{}))
{}

Both of above should be rejected as no declaration found.

[llvmbot]

@llvm/issue-subscribers-clang-frontend

[tstellar]

/cherry-pick 3784e8c

[llvmbot]

/branch llvmbot/llvm-project/issue51416

[llvmbot]

/pull-request llvmbot#148