[C++23] "no return statement in constexpr function" no longer an error with P2448

[MitalAshok]

These:

constexpr int f() {}
static_assert(__is_same(decltype([] constexpr -> int {}()), int));
consteval int g() {}
static_assert(__is_same(decltype([] consteval -> int {}()), int));

Should compile in C++23. It probably still should have a warning diagnostic (the -Wreturn-type "non-void {function|lambda} does not return a value" should be issued for f and g at least), but it shouldn't be an error (https://wg21.link/P2448R2#pnum_24)

Currently, these issue the diagnostic error: no return statement in constexpr/consteval function/lambda

Also #63617 does not apply to C++23

See also: #77753

[llvmbot]

@llvm/issue-subscribers-clang-frontend

Author: Mital Ashok (MitalAshok)

These:

constexpr int f() {}
static_assert(__is_same(decltype([] constexpr -> int {}()), int));
consteval int g() {}
static_assert(__is_same(decltype([] consteval -> int {}()), int));

Should compile in C++23. It probably still should have a warning diagnostic (the -Wreturn-type "non-void {function|lambda} does not return a value" should be issued for f and g at least), but it shouldn't be an error (<https://wg21.link/P2448R2#pnum_24>)

Currently, these issue the diagnostic error: no return statement in constexpr/consteval function/lambda

Also #63617 does not apply to C++23

See also: #77753