https://gcc.gnu.org/bugzilla/show_bug.cgi?id=125306
Bug ID: 125306
Summary: ICE when optimizing generic lambda returning nested
lambda with dependent parameter pack
Product: gcc
Version: 17.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: s.kimura.h41104 at gmail dot com
Target Milestone: ---
Compiler Explorer: https://godbolt.org/z/js5oecq4P
Reproducer:
```
void foo() {
auto L = [](auto A, auto... As) {
return [](decltype(bar)... As, decltype(A) a) { return 42; };
};
auto M = L.operator()<bool, float>(false, 3.14);
M(1.23, "abc");
}
```
Backtrace:
<source>: In function 'void foo()':
<source>:6:4: internal compiler error: in fold_convert_loc, at
fold-const.cc:2672
6 | M(1.23, "abc");
| ~^~~~~~~~~~~~~
0x29c0f58 diagnostics::context::diagnostic_impl(rich_location*,
diagnostics::metadata const*, diagnostics::option_id, char const*,
__va_list_tag (*) [1], diagnostics::kind)
???:0
0x29b5b9b internal_error(char const*, ...)
???:0
0xb2f732 fancy_abort(char const*, int, char const*)
???:0
0xbed2ee cp_fold_convert(tree_node*, tree_node*)
???:0
0xb9d24c cxx_eval_constant_expression(constexpr_ctx const*, tree_node*,
value_cat, bool*, bool*, tree_node**)
???:0
0xbb6349 maybe_constant_value(tree_node*, tree_node*, mce_value)
???:0
0x19187bc walk_tree_1(tree_node**, tree_node* (*)(tree_node**, int*, void*),
void*, hash_set<tree_node*, false, default_hash_traits<tree_node*> >*,
tree_node* (*)(tree_node**, int*, tree_node* (*)(tree_node**, int*, void*),
void*, hash_set<tree_node*, false, default_hash_traits<tree_node*> >*))
???:0
0x1919026 walk_tree_1(tree_node**, tree_node* (*)(tree_node**, int*, void*),
void*, hash_set<tree_node*, false, default_hash_traits<tree_node*> >*,
tree_node* (*)(tree_node**, int*, tree_node* (*)(tree_node**, int*, void*),
void*, hash_set<tree_node*, false, default_hash_traits<tree_node*> >*))
???:0
0xbdfec3 cp_fold_function(tree_node*)
???:0
0xc36987 finish_function(bool)
???:0
0xd82603 c_parse_file()
???:0
0xf10ea9 c_common_parse_file()
???:0
This seems a crash on invalid and goes back to gcc-11:
https://godbolt.org/z/K7bo8jfGE
