https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115078
Bug ID: 115078
Summary: ICE with invalid partial specialization of
template<auto>
Product: gcc
Version: 7.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: 420 at zerberste dot es
Target Milestone: ---
Consider the following code snippet:
```cpp
template <auto... V>
struct Proxy; // 1
template <typename... Ts, Ts... Ptr>
struct Proxy<Ptr...> {}; // 2
struct Bare {
int alt_0;
};
template struct Proxy<&Bare::alt_0>;
```
https://gcc.godbolt.org/z/46GEhfYGc
The partial specialization 2) is not more specialized than the primary template
1). Instead of emitting a helpful error, current versions of GCC crash with
><source>:5:8: internal compiler error: in unify, at cp/pt.cc:24728
> 5 | struct Proxy<Ptr...> {};
> | ^~~~~~~~~~~~~
>0x26861cc internal_error(char const*, ...)
> ???:0
>0xa5aaaf fancy_abort(char const*, int, char const*)
> ???:0
>0xcbc865 maybe_process_partial_specialization(tree_node*)
> ???:0
>0xc634da c_parse_file()
> ???:0
>0xdb8d09 c_common_parse_file()
> ???:0
>Please submit a full bug report, with preprocessed source (by using
>-freport-bug).
>Please include the complete backtrace with any bug report.
>See <https://gcc.gnu.org/bugs/> for instructions.
>Compiler returned: 1
The earliest version of GCC I was able to get to crash with this is GCC 7.2 in
C++17 mode.
This might be related to https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84822
