[Bug c++/108238] returns_nonnull attribute with auto return type fails to compile

[pinskia at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108238

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |diagnostic

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
alloc_align, alloc_size, assume_aligned, malloc attributes have a similar
issue.
const and pure does too.

```
[[gnu::const]]
auto f(){}

[[gnu::const]]
void f1(){}
```

warn_unused_result has a similar issue too:
```
[[gnu::warn_unused_result]]
auto f(){}

[[gnu::warn_unused_result]]
void f1(){}
```

There might be others too.