bug#40226: sort: expected sort order when -c in use

[Richard Ipsum]

Hi,

I'm trying to understand something and thought it would be good to ask
here.

I get different results for a case-insensitive sort using -c. My
understanding is that -f should lead to lower case characters with upper
case equivalents being converted to their upper case equivalents. This
doesn't seem to be happening for the C locale though.

% echo -e "aaaa\nAAAA" | LC_COLLATE=en_GB.UTF-8 sort -c -f -
% echo -e "aaaa\nAAAA" | LC_COLLATE=en_US.UTF-8 sort -c -f -
% echo -e "aaaa\nAAAA" | LC_COLLATE=C sort -c -f -
sort: -:2: disorder: AAAA

Is this considered a bug or an expected difference between the locales?

Thanks,
Richard