Alias template with unevaluated non-generic lambda with constexpr if statements complains about mismatched returns when used in a dependent context

[MitalAshok]

Maybe related to #58872

https://godbolt.org/z/dGT5Y8s9v

template<bool B>
using choose = decltype([] {
  if constexpr (B) {
    return 0;
  } else {
    return 0u;
  }
}());

static_assert(__is_same(choose<true>, int));
static_assert(__is_same(choose<false>, unsigned));

template<bool B>
choose<B> dependent;

<source>:6:5: error: return type 'unsigned int' must match previous return type 'int' when lambda expression has unspecified explicit return type
    6 |     return 0u;
      |     ^
<source>:2:28: note: while substituting into a lambda expression here
    2 | using choose = decltype([] {
      |                            ^
<source>:14:1: note: in instantiation of template type alias 'choose' requested here
   14 | choose<B> dependent;
      | ^

GCC and MSVC (after __is_same->std::is_same_v) are able to compile this.

It's fine when B isn't dependent. It's also fine if choose<B> is replaced with decltype([]{ ... }()).

[llvmbot]

@llvm/issue-subscribers-clang-frontend

Author: Mital Ashok (MitalAshok)

Maybe related to #58872

https://godbolt.org/z/dGT5Y8s9v

template<bool B>
using choose = decltype([] {
  if constexpr (B) {
    return 0;
  } else {
    return 0u;
  }
}());

static_assert(__is_same(choose<true>, int));
static_assert(__is_same(choose<false>, unsigned));

template<bool B>
choose<B> dependent;

<source>:6:5: error: return type 'unsigned int' must match previous return type 'int' when lambda expression has unspecified explicit return type
    6 |     return 0u;
      |     ^
<source>:2:28: note: while substituting into a lambda expression here
    2 | using choose = decltype([] {
      |                            ^
<source>:14:1: note: in instantiation of template type alias 'choose' requested here
   14 | choose<B> dependent;
      | ^

GCC and MSVC (after __is_same->std::is_same_v) are able to compile this.

It's fine when B isn't dependent. It's also fine if choose<B> is replaced with decltype([]{ ... }()).