[clang] Designated Initializer + Anonymous Union + Generic Lambda false positive assignment bug

[rfenelus]

This combination of a designated initializers, an anonymous union, and a generic lambda does not compile in Clang but does compile in GCC and MSVC. Replacing the assignment value with an expression that doesn't include a variable seems to work but breaks with variables.

int main(){
	struct Value{
		union{
			double value;
		};
	};

	auto Lambda = [](auto self) -> Value{
		double v  = 0;
		return Value{.value = v};
	};

	Lambda (Lambda);
}

Godbolt

[shafik]

Confirmed, this looks like: #57436

[llvmbot]

@llvm/issue-subscribers-clang-frontend

[Fznamznon]

I think this is fixed by #69712 , online demo - https://godbolt.org/z/bT1s85dfe .