[PATCH v2 0/2] mergetool-lib: Don't use deprecated variable to detect GNOME

To list merge tool candidates we used to use a private GNOME env variable ( GNOME_DESKTOP_SESSION_ID) that has been deprecated for long time ago and removed as part of GNOME 3.30.0 release [1].

So replace this using XDG_CURRENT_DESKTOP instead, and cleanup the code to avoid duplication and supporting KDE's kdiff3 better.

[1] https://gitlab.gnome.org/GNOME/gnome-session/-/commit/00e0e6226371d53f65

Marco Trevisan (Treviño) (2):
  mergetool-lib: use $XDG_CURRENT_DESKTOP to check GNOME
  mergetool-lib: give kdiff3 priority in KDE environments

 git-mergetool--lib.sh | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

base-commit: 85b4e0a6dc8407de6f69808d9ee6debdf167ced3
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-693%2F3v1n0%2Fdesktop-envs-fixes-v2
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-693/3v1n0/desktop-envs-fixes-v2
Pull-Request: https://github.com/gitgitgadget/git/pull/693

Range-diff vs v1:

 1:  66a026ae67 ! 1:  26b25b0d65 mergetool-lib: use $XDG_CURRENT_DESKTOP to check GNOME
     @@ Commit message
          variable (GNOME_DESKTOP_SESSION_ID) that has been deprecated for long time ago
          and removed as part of GNOME 3.30.0 release [1].
      
     -    So, git should instead check the XDG_CURRENT_DESKTOP env variable, that
     -    is supported by all the desktop environments.
     +    So, git should instead primarily check the XDG_CURRENT_DESKTOP env variable,
     +    that is now supported by all the desktop environments.
      
          Since the variable is actually a colon-separated list of names that the current
     -    desktop is known as, we need to go through all the values to ensure
     -    we're using GNOME.
     +    desktop is known as, we need to check if the value is set if we're using GNOME.
      
          [1] https://gitlab.gnome.org/GNOME/gnome-session/-/commit/00e0e6226371d53f65
      
     @@ git-mergetool--lib.sh: run_merge_cmd () {
       }
       
      +is_desktop () {
     -+	IFS=':'
     -+	for desktop in ${XDG_CURRENT_DESKTOP}
     -+	do
     -+		if test "$desktop" = "$1"
     -+		then
     -+			return 0
     -+		fi
     -+	done
     -+
     -+	return 1
     ++	case ":$XDG_CURRENT_DESKTOP:" in
     ++	*:$1:*)
     ++		return 0
     ++		;;
     ++	*)
     ++		return 1
     ++		;;
     ++	esac
      +}
      +
       list_merge_tool_candidates () {
     @@ git-mergetool--lib.sh: list_merge_tool_candidates () {
       	if test -n "$DISPLAY"
       	then
      -		if test -n "$GNOME_DESKTOP_SESSION_ID"
     -+		if is_desktop "GNOME"
     ++		if is_desktop "GNOME" || test -n "$GNOME_DESKTOP_SESSION_ID"
       		then
       			tools="meld opendiff kdiff3 tkdiff xxdiff $tools"
       		else
 2:  fc0d2b103e < -:  ---------- mergetool-lib: keep a list of cross desktop merge tools
 3:  37090d2322 ! 2:  c18a5edf50 mergetool-lib: give kdiff3 prioirty in KDE environments
     @@ Metadata
      Author: Marco Trevisan (Treviño) <mail@3v1n0.net>
      
       ## Commit message ##
     -    mergetool-lib: give kdiff3 prioirty in KDE environments
     +    mergetool-lib: give kdiff3 priority in KDE environments
      
          Signed-off-by: Marco Trevisan (Treviño) <mail@3v1n0.net>
      
       ## git-mergetool--lib.sh ##
      @@ git-mergetool--lib.sh: list_merge_tool_candidates () {
     - 	fi
     - 	if test -n "$DISPLAY"
     - 	then
     --		cross_desktop_tools="opendiff kdiff3 tkdiff xxdiff"
     -+		cross_desktop_tools="opendiff tkdiff xxdiff"
     - 		if is_desktop "GNOME"
     + 		if is_desktop "GNOME" || test -n "$GNOME_DESKTOP_SESSION_ID"
       		then
     --			tools="meld $cross_desktop_tools $tools"
     -+			tools="meld $cross_desktop_tools kdiff3 $tools"
     -+		elif is_desktop "KDE"
     + 			tools="meld opendiff kdiff3 tkdiff xxdiff $tools"
     ++		elif is_desktop "KDE" || test x"$KDE_FULL_SESSION" = x"true"
      +		then
     -+			tools="kdiff3 $cross_desktop_tools meld $tools"
     ++			tools="kdiff3 opendiff tkdiff xxdiff meld $tools"
       		else
     --			tools="$cross_desktop_tools meld $tools"
     -+			tools="$cross_desktop_tools kdiff3 meld $tools"
     + 			tools="opendiff kdiff3 tkdiff xxdiff meld $tools"
       		fi
     - 		tools="$tools gvimdiff diffuse diffmerge ecmerge"
     - 		tools="$tools p4merge araxis bc codecompare"