https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116552
Bug ID: 116552
Summary: [ABI] Incorrect mangling for CTAD placeholder
referencing template template parameter
Product: gcc
Version: 14.2.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: mizvekov at gmail dot com
Target Milestone: ---
For a test case like:
```C++
template <template <class> class TemplateTemplateParam>
void create_unique()
requires (TemplateTemplateParam{0}, true) {}
template <class Fn> struct A {
constexpr A(Fn) {};
};
template void create_unique<A>();
```
https://compiler-explorer.com/z/9446so8fh
The template parameter name ends up appearing in the mangling for
create_unique:
_Z13create_uniqueI1AEvvQcmtl21TemplateTemplateParamLi0EELb1E(
Normally in these cases we would use the template-prefix production, which
includes a special case for mangling template parameters based on their index.
Following the discussion in
https://github.com/itanium-cxx-abi/cxx-abi/issues/109, it seems like consensus
on the template-prefix production was reached.
Reference to clang PR dealing with this issue:
https://github.com/llvm/llvm-project/pull/106335
