https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117035
Bug ID: 117035
Summary: ICE in unify, at cp/pt.cc:25410, when specifying
lambda expression template argument in partial
specialization
Product: gcc
Version: 14.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: guyutongxue at 163 dot com
Target Milestone: ---
```
template <int, auto = [] {}>
struct Foo {};
template <int N>
struct Foo<N> {};
constexpr auto oops = Foo<0>{};
```
causes GCC ICE in all versions from 9.1 to current trunk (15.0).
Clang and MSVC compiles, while EDG rejects this code. Godbolt:
https://godbolt.org/z/xWToxf39b
GCC 14.2.0 output:
<source>:7:30: internal compiler error: in unify, at cp/pt.cc:25410
7 | constexpr auto oops = Foo<0>{};
| ^
0x2031cbc internal_error(char const*, ...)
???:0
0x77895f fancy_abort(char const*, int, char const*)
???:0
0x928a6d most_specialized_partial_spec(tree_node*, int, bool)
???:0
0x94c21e instantiate_class_template(tree_node*)
???:0
0x98936b complete_type(tree_node*)
???:0
0x95f4d9 finish_compound_literal(tree_node*, tree_node*, int, fcl_t)
???:0
0x90ee14 c_parse_file()
???:0
0xa0d1b9 c_common_parse_file()
???:0
