aaron.ballman added a comment.
In D133289#4489883 <https://reviews.llvm.org/D133289#4489883>, @aaron.ballman
wrote:
> - `_Atomic auto x = 12;` is now something we should be accepting and deduce
> as an `_Atomic int`
The committee is discussing this again on the reflectors. Thus far, almost
everyone reads the standard the same way as GCC did with their implementation,
which matches what I suggest above. However, there are folks who are claiming
we should not be able to deduce the derived type because `_Atomic` forms an
entirely new type and thus isn't actually a qualifier (and there are some words
in the standard that could maybe be read as supporting that). The most
conservative approach is to reject using `_Atomic auto` for right now so users
don't build a reliance on it. Eventually WG14 will make a decision and we can
relax that diagnostic then if we need to. Sorry for the confusion on this topic!
================
Comment at: clang/test/Sema/c2x-auto.c:119
+ return x;
+}
----------------
aaron.ballman wrote:
> Some additional test cases to consider:
> ```
> _Complex auto i = 12.0; // Should be rejected because _Complex is a type
> specifier; however,
> // when auto becomes a type specifier, this should be
> accepted. GCC
> // rejects but if we end up accepting, I won't be sad
> -- we'll need an
> // extension warning in that case though.
>
> void foo(void) {
> extern void foo(int a, int array[({ auto x = 12; x;})]); // This is a use
> of `auto` within function prototype
> // scope, but
> should still be accepted.
> }
> ```
The suggested comment I have isn't fully correct. It should be rejected because
_Complex is a type specifier, but when auto becomes a type specifier, I think
_Complex perhaps should still not deduce. Consider this analogous case (which
could be a fun test case as well):
```
signed auto a = 1L;
```
`signed` is a type specifier as well, and this is not accepted in C++ (so we
don't want to accept it in C either).
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D133289/new/
https://reviews.llvm.org/D133289
_______________________________________________
cfe-commits mailing list
cfe-commits@lists.llvm.org
https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
