I haven't tested yet but +1 for the feature. I guess the API didn't exist at the time collation support was added.
Good to hear.
This conversion makes sense, to keep the user experience the same across platforms. Nitpick on the comment: why ANSI? I think we can call "en_NZ" a POSIX locale identifier[1], and I think we can call "en-NZ" a BCP 47 language tag.
POSIX also works for me.
When would the full set of locales not be installed on a Windows system, and why does this need Visual Studio? Wondering if this test will work with some of the frankenstein/cross toolchains tool chains (not objecting if it doesn't and could be skipped, just trying to understand the comment).
What I meant to say is that to run the test, you need a database that has successfully run pg_import_system_collations. This would be also possible in Mingw for _WIN32_WINNT> = 0x0600, but the current value in src\include\port\win32.h is _WIN32_WINNT = 0x0501 when compiling with Mingw.
