[Bug tree-optimization/106922] [12/13 Regression] Bogus uninitialized warning on boost::optional<<std::vector<std::string>>>, missed FRE

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106922

--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
The rev. in question shows changes in what PRE does.  Before the change
disabling PRE also leads to the diagnostic so there's a missed optimization
there.  I see less fully redundant values discovered.

I'm trying to reduce a testcase.