In french locale this only occurs for case insensitive sorting. In "C" locale, it always occur.

Snark: what is your locale?

Please show the output of the "locale" command.

The issue is in go_string_cmp_ignorecase. It should call g_utf8_collate instead of strcmp. Of course, we should call g_utf8_collate_key at some point.

Created attachment 171826 [details] [review]
Proposed patch.

Do we really need to store the string case insensitive version? If yes, the patch is not what we want.

$ locale
LANG=fr_FR.UTF-8
LC_CTYPE="fr_FR.UTF-8"
LC_NUMERIC="fr_FR.UTF-8"
LC_TIME="fr_FR.UTF-8"
LC_COLLATE="fr_FR.UTF-8"
LC_MONETARY="fr_FR.UTF-8"
LC_MESSAGES="fr_FR.UTF-8"
LC_PAPER="fr_FR.UTF-8"
LC_NAME="fr_FR.UTF-8"
LC_ADDRESS="fr_FR.UTF-8"
LC_TELEPHONE="fr_FR.UTF-8"
LC_MEASUREMENT="fr_FR.UTF-8"
LC_IDENTIFICATION="fr_FR.UTF-8"
LC_ALL=

Created attachment 171843 [details] [review]
Enhanced patch.

Review of attachment 171843 [details] [review]:

Close.

GO_STRING_HAS_CASEFOLDED_COLLATE is the same as GO_STRING_HAS_CASEFOLD.  I don't think that
will work.

Then go_string_get_casefold is going to have clear 
GO_STRING_HAS_CASEFOLDED_COLLATE being it will overwrite the string.

This code is getting a tad complicated.

Created attachment 171845 [details] [review]
fixed patch

Created attachment 171848 [details] [review]
new revised patch

This problem has been fixed in our software repository. The fix will go into the next software release. Thank you for your bug report.