Re: [v2 PATCH] expand: Always quote caret when using fnmatch

[Stephane Chazelas <stephane@chazelas.org>]

2022-02-21 17:06:13 +0000, Harald van Dijk:
[...]
> > If you want to escape ^ to always be treated as a literal when calling
> > fnmatch(), you have to spell it something like [[=^=]...], not [\^...]
> > (that is, since \^ inside [] does NOT treat the \ as an escape
> > character, but as yet another literal character as part of the brakcet
> > group, you instead have to resort to calling out the literal character
> > ^ via alternative spellings such as by a collation equivalent).
> 
> This is correct for regular expressions, unspecified for shell patterns in
> general after bug 1234 was resolved, and always incorrect for fnmatch()
> after bug 1190 was resolved. In fnmatch(), backslash has to work even inside
> bracket expressions. Whether it had to may not previously have been clear in
> the standard, but it has been made clear now and that is also how it works
> in glibc. That part of the patch is not a problem.
[...]

Thanks, and sorry about that. I was actually the one raising bug
1234 and misremembered the outcome.

case $var in ([\!x])

is specified, but:

pattern='[\!x]'
case $var in ($pattern)

is not indeed, so, the behaviour  of:

sh -c 'case "\\" in ($1) echo match; esac' sh '[\^x]'

is unspecified, so even though that patch changes the behaviour
in this instance, it's still not a conformance bug.

-- 
Stephane