https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120051
--- Comment #5 from Christoph Reiter <reiter.christoph at gmail dot com> --- Thanks for working on this. I applied the gcc patch and can confirm that the original example no longer crashes. I found another crasher though and reduced it to: $ cat test.c // gcc -O1 -gcodeview -c test2.c typedef union a b; int c(b *) {} $ gcc -O1 -gcodeview -c test2.c test2.c:3:1: internal compiler error: Segmentation fault 3 | int c(b *) {} | ^~~