[Bug c++/102933] New: Can't use CTAD in template argument

[johelegp at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102933

            Bug ID: 102933
           Summary: Can't use CTAD in template argument
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Keywords: rejects-valid
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: johelegp at gmail dot com
                CC: johelegp at gmail dot com
  Target Milestone: ---

See https://godbolt.org/z/P8xq8h9M1.

```C++
template<class T> struct X { T t; };
template<X> void f();
template<class T> void g() {
  f<X{T{0}}>();
}
int main() {
  g<int>();
}
```

```
<source>: In function 'void g()':
<source>:7:5: error: invalid use of 'X<...auto...>' in template argument
    7 |   f<X{T{0}}>();
      |     ^
Compiler returned: 1
```