pkg/59895: bash-completion-2.17.0 started to error out `bash: warning: setlocale: LC_COLLATE: cannot change locale (en_US.UTF-8)`

["leot%NetBSD.org@localhost via gnats" <gnats-admin%NetBSD.org@localhost>]

>Number:         59895
>Category:       pkg
>Synopsis:       bash-completion-2.17.0 started to erroring out `bash: warning: setlocale: LC_COLLATE: cannot change locale (en_US.UTF-8)`
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    pkg-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Jan 06 22:55:00 +0000 2026
>Originator:     Leonardo Taccari
>Release:        NetBSD 10.1_STABLE
>Organization:
The NetBSD Foundation
>Environment:
System: NetBSD pinebookpro 10.1_STABLE NetBSD 10.1_STABLE (GENERIC64) #0: Fri Dec 26 12:53:23 UTC 2025 mkrepro%mkrepro.NetBSD.org@localhost:/usr/src/sys/arch/evbarm/compile/GENERIC64 evbarm
Architecture: aarch64
Machine: evbarm
>Description:
	When using shells/bash-completion and having set LANG="en_US.UTF-8"
	trying to complete possible globs spams the terminal with:

	 bash: warning: setlocale: LC_COLLATE: cannot change locale (en_US.UTF-8)

	This seems a problem introduced with bash-completion-2.17.0.
	Previous bash-completion-2.11 did not had such problem.

	The completions are usable but this is pretty annoying.
>How-To-Repeat:
	A simple reproducer that directly calls problematic function:

	 $ export LANG=en_US.UTF-8 # or assume that it is present in ~/.profile
	 [...]
         $ _comp_expand_glob files '/tmp/reproducer-*'
         bash: warning: setlocale: LC_COLLATE: cannot change locale (en_US.UTF-8)
	
	Interactively this can be reproduced via e.g.

	 man m<tab>
	
	So, by typing "man m" and the tab character to complete.
>Fix:
	Yes, please!

	_comp_expand_glob() function of share/bash-completion/bash_completion
	now have:

	 # To canonicalize the sorting order of the generated paths, we set
	 # LC_COLLATE=C and unset LC_ALL while preserving LC_CTYPE.
	 local LC_COLLATE=C LC_CTYPE=${LC_ALL:-${LC_CTYPE:-${LANG-}}} LC_ALL=
	
	NetBSD setlocale(3) says under RETURN VALUES:

	     Currently, setlocale() returns NULL and fails to change the locale when
	     LC_COLLATE is modified independently of other values.
	
	...and under CAVEATS:

	     LC_COLLATE is unimplemented (but does not make sense for many languages).

	Probably this can be due that.

	Getting rid of "LC_COLLATE=C" on that local remove that warnings.
	Maybe we should conditionalize that for [[ $OSTYPE != *netbsd* ]] so
	that such local is not set on NetBSD.