https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120291
Bug ID: 120291
Summary: internal compiler error: in tsubst_pack_expansion, at
cp/pt.cc:13941 with -std=c++20
Product: gcc
Version: 16.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: mario.rodriguezb1 at um dot es
Target Milestone: ---
It ICEs in invalid this invalid code:
```
#include <iostream>
template<int x> decltype(auto) f() {
return [](auto... args) mutable requires requires {
A<args...};
}{
[](auto... ){
A<1> a;
}(...);
};
}
int main() {
f<0>()(A<0>{});
}
```
Stack dump
```
<source>:3:9: internal compiler error: in tsubst_pack_expansion, at
cp/pt.cc:13941
3 | return [](auto... args) mutable requires requires {
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
4 | A<args...};
| ~~~~~~~~~~
0x2943505 diagnostic_context::diagnostic_impl(rich_location*,
diagnostic_metadata const*, diagnostic_option_id, char const*, __va_list_tag
(*) [1], diagnostic_t)
???:0
0x2961276 internal_error(char const*, ...)
???:0
0xad8a2c fancy_abort(char const*, int, char const*)
???:0
0xd3430b tsubst(tree_node*, tree_node*, int, tree_node*)
???:0
0xd4f780 tsubst_lambda_expr(tree_node*, tree_node*, int, tree_node*)
???:0
0xd2772d instantiate_decl(tree_node*, bool, bool)
???:0
0xbe0833 maybe_instantiate_decl(tree_node*)
???:0
0xbe2527 mark_used(tree_node*, int)
???:0
0xb1020e build_new_function_call(tree_node*, vec<tree_node*, va_gc,
vl_embed>**, int)
???:0
0xd7dc7c finish_call_expr(tree_node*, vec<tree_node*, va_gc, vl_embed>**, bool,
bool, int)
???:0
0xcfcda3 c_parse_file()
???:0
0xe5f7c9 c_common_parse_file()
???:0
```
To quickly reproduce with -std=c++20:
https://godbolt.org/z/73r594779
