https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103339
Bug ID: 103339
Summary: [modules] ICE in exporting module on use of outside
specialization
Product: gcc
Version: 12.0
Status: UNCONFIRMED
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/onW6h5vej.
mod.cpp:
```C++
export module mod;
export template<class T> struct trait { };
export template<class> concept C = true;
template<class T> concept has_trait = C<trait<T>>;
```
test.cpp:
```C++
import mod;
template<C T> struct trait<T> { };
```
Output:
```
test.cpp:2:31: internal compiler error: in import_entity_index, at
cp/module.cc:3953
2 | template<C T> struct trait<T> { };
| ^
0x206aac9 internal_error(char const*, ...)
???:0
0x7d92db fancy_abort(char const*, int, char const*)
???:0
0x966072 module_may_redeclare(tree_node*)
???:0
0xaab517 begin_class_definition(tree_node*)
???:0
0xa0b065 c_parse_file()
???:0
0xb931d2 c_common_parse_file()
???:0
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <https://gcc.gnu.org/bugs/> for instructions.
```
Workaround:
```diff
-template<class T> concept has_trait = C<trait<T>>;
+template<class T> concept has_trait = C<trait<std::type_identity_t<T>>>;
```
As per the logic in https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99631#c1, this
isn't marked with any of the ice-* keywords.
