[Bug c++/101498] New: gcc accepts template code with 'auto' as subtype

[fchelnokov at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101498

            Bug ID: 101498
           Summary: gcc accepts template code with 'auto' as subtype
           Product: gcc
           Version: 11.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: fchelnokov at gmail dot com
  Target Milestone: ---

The code as follows:
```
template <typename T> struct S;
void foo(S<auto>);

```
is ill-formed and must be rejected, but gcc accepts it:
https://gcc.godbolt.org/z/bMof1xsEa