https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105732
--- Comment #4 from Loren Osborn <linux_dr at yahoo dot com> --- (*Comment lost in submit collision*) Just a couple last notes: 1) Go here first: https://godbolt.org/z/bsenoqdjv. (Easy to reproduce bug in a simple link.) 2) I filed this bug against 11.3.0, as that is when the regression appeared, but Compiler Explorer seems to show that this is still a current bug on trunk Regarding Andrew Pinski's shortening of the code sample, I mostly left the comments there for context. (I actually found this bug by accident: This code was never intended to run against GCC >= 8. Due to a bug in my code, I found this bug.) This is chopped down from a ~460 line header file already. I hope that helps!
