Peter Eisentraut <peter.eisentraut@2ndquadrant.com> writes:
> I tried it on Debian stable with gcc 6.3.0 and couldn't reproduce it.
> cc (Debian 6.3.0-18+deb9u1) 6.3.0 20170516
Oh ... *that's* interesting. Are we sure this is the version in use
on coverage.postgresql.org?
Also, I just finished searching in vain for any plausibly-matching
bug at https://gcc.gnu.org/bugzilla/. I did find a few reports
suggesting that gcov could misbehave with nondefault build options
such as LTO. And "gcov -a" has also had issues. So maybe we ought
to have a look at exactly what coverage.postgresql.org's build
recipe is.
regards, tom lane