[Bug tree-optimization/92860] [8/9/10/11 regression] Global flags affected by -O settings are clobbered by optimize attribute

[dcb314 at hotmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92860

--- Comment #27 from David Binderman <dcb314 at hotmail dot com> ---
(In reply to Martin Liška from comment #25)
> Yes, it's definitely related.
> Please attach -E file and a command line.

Problem stills exists in the g++ compiler dated 20200623, but anything 
I do to reduce the problem makes it go away ;-<

Confirmation sought that the stack backtrace I provided shows
that the problem is a bug in the pre-processor. 

If so, -E isn't going to help.