[Bug libstdc++/110167] New: excessive compile time when optimizing std::to_array

[nightstrike at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110167

            Bug ID: 110167
           Summary: excessive compile time when optimizing std::to_array
           Product: gcc
           Version: 13.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: nightstrike at gmail dot com
  Target Milestone: ---

#include <array>
int f[262144]; auto g(void) { return std::to_array(f); }

(Thanks to Andrew for help reducing!)

Baseline run:

$ time g++ test.cc -std=gnu++20 -O0 -c
real    0m17.274s
user    0m16.806s
sys     0m0.119s


at -O1, 2, 3, or fast, it takes too long to ever finish.  I killed it after 15
minutes.

For the curious, that array size is 512*512.  I didn't bisect to see where it
starts to blow up.