[Bug c++/125211] New: [13/14/15/16/17 Regression] ICE with an anonumous union in a generic lambda defined as part of a templated variable

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=125211

            Bug ID: 125211
           Summary: [13/14/15/16/17 Regression] ICE with an anonumous
                    union in a generic lambda defined as part of a
                    templated variable
           Product: gcc
           Version: 16.0
            Status: UNCONFIRMED
          Keywords: c++-lambda, ice-on-valid-code
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: pinskia at gcc dot gnu.org
  Target Milestone: ---

testcase:
```
template <typename T>
auto f = [](auto... args) {
  union {
    char c;
  };
  c = 'a';
};

void g() { f<void>(); }
```

Forwarded from
https://discourse.llvm.org/t/collection-of-minimal-clang-frontend-assertion-failure-test-cases/90735/6.

This was actually the only testcase of this suite which ICEs with GCC too.

This used to work with GCC 7.5.0.