https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103341
Bug ID: 103341
Summary: ICE type of variable instantiation constrained on
template parameter
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/68GYeKqK4.
```C++
template<class, class> struct is_same { };
template<class T, class U> concept same_as = is_same<T, U>::value;
template<class T> inline constexpr same_as<T> auto trait_v{1};
using _ [[maybe_unused]] = decltype(trait_v<int>);
```
Output:
```
<source>: In instantiation of 'constexpr const auto [requires
::same_as<<placeholder>, T>] trait_v<int>':
<source>:4:37: required from here
<source>:3:52: internal compiler error: tree check: accessed elt 1 of
'tree_vec' with 0 elts in hash, at cp/constraint.cc:2503
3 | template<class T> inline constexpr same_as<T> auto trait_v{1};
| ^~~~~~~
0x206d4e9 internal_error(char const*, ...)
???:0
0x6da40c tree_vec_elt_check_failed(int, int, char const*, int, char const*)
???:0
0x85fca0 sat_hasher::hash(sat_entry*)
???:0
0x85aed7 satisfaction_cache::satisfaction_cache(tree_node*, tree_node*,
sat_info)
???:0
0x85f01a constraints_satisfied_p(tree_node*, tree_node*)
???:0
0xa3384b do_auto_deduction(tree_node*, tree_node*, tree_node*, int,
auto_deduction_context, tree_node*, int)
???:0
0x8d2c1d cp_finish_decl(tree_node*, tree_node*, bool, tree_node*, int)
???:0
0xa46987 instantiate_decl(tree_node*, bool, bool)
???:0
0x8e7c9e maybe_instantiate_decl(tree_node*)
???:0
0x8e9760 mark_used(tree_node*, int)
???:0
0xabe557 finish_id_expression(tree_node*, tree_node*, tree_node*, cp_id_kind*,
bool, bool, bool*, bool, bool, bool, bool, char const**, unsigned int)
???:0
0xa0cc65 c_parse_file()
???:0
0xb94bf2 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.
Compiler returned: 1
```
