[Bug c++/91525] ICE (Segmentation Fault) on a bool conversion operator with concepts

[gcc-bugs at marehr dot dialup.fu-berlin.de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91525

--- Comment #3 from gcc-bugs at marehr dot dialup.fu-berlin.de ---
On gcc-10 I get now the following stacktrace:

```
g++-git -std=c++17 -fconcepts -c ice.cpp
main.cpp: In function ‘std::string e()’:
main.cpp:46:16: internal compiler error: Segmentation fault
   46 |   std::cout << o;
      |                ^
0xc5b15f crash_signal
        /home/marehr/Packages/gcc-git/src/gcc/gcc/toplev.c:328
0x645182 compare_ics
        /home/marehr/Packages/gcc-git/src/gcc/gcc/cp/call.c:10538
0x648c84 joust
        /home/marehr/Packages/gcc-git/src/gcc/gcc/cp/call.c:11191
0x649cbc tourney
        /home/marehr/Packages/gcc-git/src/gcc/gcc/cp/call.c:11630
0x649fd1 build_user_type_conversion_1
        /home/marehr/Packages/gcc-git/src/gcc/gcc/cp/call.c:4165
0x64b435 implicit_conversion
        /home/marehr/Packages/gcc-git/src/gcc/gcc/cp/call.c:2053
0x64baf0 good_conversion(tree_node*, tree_node*, tree_node*, int, int)
        /home/marehr/Packages/gcc-git/src/gcc/gcc/cp/call.c:2093
0x77183e check_non_deducible_conversion
        /home/marehr/Packages/gcc-git/src/gcc/gcc/cp/pt.c:21173
0x77183e check_non_deducible_conversions
        /home/marehr/Packages/gcc-git/src/gcc/gcc/cp/pt.c:20645
0x77183e fn_type_unification(tree_node*, tree_node*, tree_node*, tree_node*
const*, unsigned int, tree_node*, unification_kind_t, int, conversion**, bool,
bool)
        /home/marehr/Packages/gcc-git/src/gcc/gcc/cp/pt.c:20947
0x64e879 add_template_candidate_real
        /home/marehr/Packages/gcc-git/src/gcc/gcc/cp/call.c:3394
0x64f046 add_template_candidate
        /home/marehr/Packages/gcc-git/src/gcc/gcc/cp/call.c:3479
0x64f046 add_candidates
        /home/marehr/Packages/gcc-git/src/gcc/gcc/cp/call.c:5805
0x64f612 add_candidates
        /home/marehr/Packages/gcc-git/src/gcc/gcc/cp/call.c:5720
0x64f612 add_operator_candidates
        /home/marehr/Packages/gcc-git/src/gcc/gcc/cp/call.c:5909
0x6545eb build_new_op_1
        /home/marehr/Packages/gcc-git/src/gcc/gcc/cp/call.c:6132
0x6551ed build_new_op(op_location_t const&, tree_code, int, tree_node*,
tree_node*, tree_node*, tree_node**, int)
        /home/marehr/Packages/gcc-git/src/gcc/gcc/cp/call.c:6520
0x7a563a build_x_binary_op(op_location_t const&, tree_code, tree_node*,
tree_code, tree_node*, tree_code, tree_node**, int)
        /home/marehr/Packages/gcc-git/src/gcc/gcc/cp/typeck.c:4245
0x70c7ad cp_parser_binary_expression
        /home/marehr/Packages/gcc-git/src/gcc/gcc/cp/parser.c:9650
0x70d575 cp_parser_assignment_expression
        /home/marehr/Packages/gcc-git/src/gcc/gcc/cp/parser.c:9785
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <https://bugs.archlinux.org/> for instructions
```