Re: [PG19] ILIKE index scan misses rows with a libc UTF-8 collation on macOS

Thanks Fujii and Chao for testing.

> Given that this issue has only been confirmed on macOS so far, does it
> make sense to add the extra checks only for macOS, like this:

I would keep it on all platforms. ILIKE compares with towlower() on
every platform, so this check is what it needs everywhere. Where the C
library is consistent it changes nothing. I went over every code point
with glibc 2.39 and musl 1.2.5, and the new checks add no character
there. It only runs at plan time.

> Then, I would suggest adding a regression test so that CI can help
> check whether the problem exists on other platforms.

Done in 0002.

0001 is unchanged.

Thanks,
Shihao