Re: [PG19] psql backslash commands fail with translated messages and a non UTF-8 client encoding

Hi,

Looks like we agree on the three-way rule, with the API Tom suggested.

v3 attached, done the way Tom suggested. addQueryComment() uses the
translation only if it is plain ASCII, or if gettext's output
encoding, client_encoding and server_encoding are known to match.
Otherwise it uses the English label.

> Matching all three encodings may not be sufficient, since, e.g.,
> OUTPUT_CHARSET can also affect the locale encoding?

Yes. psql never calls bind_textdomain_codeset(), so OUTPUT_CHARSET is
the only override. With all three UTF8 and OUTPUT_CHARSET=EUC-JP,
19rc1 fails with invalid byte sequence. v3 uses English whenever
OUTPUT_CHARSET is set.

> I'm also not sure whether matching all three is sufficient on Windows.

I can’t test there. psql and libintl work out the code page in different
ways on
Windows, and I could not convince myself they always agree. So on Windows
v3 uses the English label whenever the translation is not plain ASCII.

We may lose a little since the CJK code pages map to SJIS, GBK, BIG5
and UHC, which can never be server_encoding.

Thanks,
Shihao