Comment 2 for bug 1915640

I think this is a duplicate of 99071, which hadn't been done when Mattias tested.

However, I am getting a different ICE:
devvm1702:235>./xg++ -B./ -nostdinc++ -I../x86_64-pc-linux-gnu/libstdc++-v3/include/x86_64-pc-linux-gnu -I../x86_64-pc-linux-gnu/libstdc++-v3/include -I../../..//src/libstdc++-v3/libsupc++ -I../../../src/libstdc++-v3/include/backward -I../../../src/libstdc++-v3/testsuite/util -std=c++20 -fmodules-ts -x c++-system-header iostream
devvm1702:236>./xg++ -B./ -nostdinc++ -I../x86_64-pc-linux-gnu/libstdc++-v3/include/x86_64-pc-linux-gnu -I../x86_64-pc-linux-gnu/libstdc++-v3/include -I../../..//src/libstdc++-v3/libsupc++ -I../../../src/libstdc++-v3/include/backward -I../../../src/libstdc++-v3/testsuite/util -std=c++20 -fmodules-ts -x c++-system-header utility
devvm1702:237>./xg++ -B./ -nostdinc++ -I../x86_64-pc-linux-gnu/libstdc++-v3/include/x86_64-pc-linux-gnu -I../x86_64-pc-linux-gnu/libstdc++-v3/include -I../../..//src/libstdc++-v3/libsupc++ -I../../../src/libstdc++-v3/include/backward -I../../../src/libstdc++-v3/testsuite/util -std=c++20 -fmodules-ts -x c++-system-header algorithm
../x86_64-pc-linux-gnu/libstdc++-v3/include/algorithm: internal compiler error: in make_dependency, at cp/module.cc:12514
0xd06a9a depset::hash::make_dependency(tree_node*, depset::entity_kind)
 ../../../src/gcc/cp/module.cc:12514
0xd07ae1 depset::hash::add_dependency(tree_node*, depset::entity_kind)
 ../../../src/gcc/cp/module.cc:12712
0xcf24e0 trees_out::decl_node(tree_node*, walk_kind)
 ../../../src/gcc/cp/module.cc:8605
0xcf4a73 trees_out::tree_node(tree_node*)
 ../../../src/gcc/cp/module.cc:9168
0xce2700 trees_out::vec_chained_decls(tree_node*)
 ../../../src/gcc/cp/module.cc:4981
0xd02052 trees_out::write_class_def(tree_node*)
 ../../../src/gcc/cp/module.cc:11737

which does appear to be new.