[Bug c++/120531] [13/14/15/16 Regression] ICE Seg fault in gimplify_expr with enum with an invalid underlying type since version 13.1

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120531

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
The enum type looks like it was not "laid out".



This fixes the ICE but I am not 100% sure if it is the correct fix:
```
[apinski@xeond2 gcc]$ git diff
diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc
index 9a20ed62738..5d8af6dd8f8 100644
--- a/gcc/cp/decl.cc
+++ b/gcc/cp/decl.cc
@@ -17736,6 +17736,7 @@ start_enum (tree name, tree enumtype, tree
underlying_type,
        {
          error ("underlying type %qT of %qT must be an integral type",
                 underlying_type, enumtype);
+         copy_type_enum (enumtype, integer_type_node);
          ENUM_UNDERLYING_TYPE (enumtype) = integer_type_node;
        }
     }

```