bug#21816: elisp-mode-tests fails on a case-preserving filesystem

[Stephen Leake]

Alexis <flexibeast@gmail.com> writes:

> Stephen Leake <stephen_leake@stephe-leake.org> writes:
>
>> I did not try a non-ASCII file name; I'm not sure how to construct
>> one that has a non-ASCII casing issue.
>
> Perhaps use German Eszett / sharp S / Unicode LATIN SMALL LETTER SHARP
> S? The words 'Strasse' and 'Straße' are equivalent, , but typically the
> latter is up-cased to 'STRASSE', rather than 'STRAẞE'

Windows 8.1 lets me create:

"c:/tmp/STRAẞE.text" ;; LATIN CAPITAL LETTER SHARP S
"c:/tmp/Straße.text" ;; LATIN SMALL LETTER SHARP S
"c:/tmp/Strasse.text"

The font I'm using on Windows has no glyph for LATIN CAPITAL LETTER
SHARP S; on Debian, it's the same glyph as LATIN SMALL LETTER SHARP S,
which is confusing in this context.

file-truename follows Windows:

(file-truename "c:/tmp/Straẞe.text");; CAPITAL
"c:/tmp/STRAẞE.text";; CAPITAL

(file-truename "c:/tmp/Straße.text");; SMALL
"c:/tmp/Straße.text";; SMALL

(file-truename "c:/tmp/Strasse.text")
"c:/tmp/Strasse.text"

As do upcase, downcase:
(upcase "Straße.text") ;; SMALL
"STRAßE.TEXT" ;; SMALL

(downcase "Straẞe.text") ;; CAPITAL
"straẞe.text" ;; CAPITAL

I think changing CAPITAL ẞ to "SS" is not strictly a "casing" issue? But
perhaps it should be considered for a canonical file name on a
case-insensitive system?

Perhaps Windows has simply not yet implemented this recent addition to
Unicode? In which case, we need a better example to test with.

Debian testing (a few months old) running in VMWare under Windows 8.1
shows the same behavior. But Debian is case-sensitive, so that's not an
issue here, I think. The upcase/downcase is wrong, but I'm guessing
that's due to the CAPITAL being a recent addition to Unicode. 

-- 
-- Stephe