https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61602
tbsaunde at gcc dot gnu.org changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |tbsaunde at gcc dot gnu.org --- Comment #4 from tbsaunde at gcc dot gnu.org --- So, during the single use pass we have 3 variables in symtab a, b and d. a->ref_list.referring is empty so the map doesn't contain an entry for a. So single_use_map is only { b-> main, d -> main } and we assert because single_use_map.get(a) returns NULL. However I'm not sure if the problem is the assert being incorrect or if a.ref_list.referring should contain main.