[PATCH 0/4] Documentation: Auto-generate merge tool lists

@@ -32,17 +32,10 @@ check_unchanged () {
 	fi
 }
 
-valid_tool_config () {
-	if test -n "$(get_merge_tool_cmd "$1")"
-	then
-		return 0
-	else
-		return 1
-	fi
-}
-
 valid_tool () {
-	setup_tool "$1" || valid_tool_config "$1"
+	setup_tool "$1" && return 0
+	cmd=$(get_merge_tool_cmd "$1")
+	test -n "$cmd"
 }
 
 setup_tool () {

@@ -96,14 +89,13 @@ setup_tool () {
 }
 
 get_merge_tool_cmd () {
-	# Prints the custom command for a merge tool
 	merge_tool="$1"
 	if diff_mode
 	then
-		echo "$(git config difftool.$merge_tool.cmd ||
-			git config mergetool.$merge_tool.cmd)"
+		git config "difftool.$merge_tool.cmd" ||
+		git config "mergetool.$merge_tool.cmd"
 	else
-		echo "$(git config mergetool.$merge_tool.cmd)"
+		git config "mergetool.$merge_tool.cmd"
 	fi
 }
 

@@ -114,7 +106,7 @@ run_merge_tool () {
 	GIT_PREFIX=${GIT_PREFIX:-.}
 	export GIT_PREFIX
 
-	merge_tool_path="$(get_merge_tool_path "$1")" || exit
+	merge_tool_path=$(get_merge_tool_path "$1") || exit
 	base_present="$2"
 	status=0
 

@@ -145,7 +137,7 @@ run_merge_tool () {
 
 # Run a either a configured or built-in diff tool
 run_diff_cmd () {
-	merge_tool_cmd="$(get_merge_tool_cmd "$1")"
+	merge_tool_cmd=$(get_merge_tool_cmd "$1")
 	if test -n "$merge_tool_cmd"
 	then
 		( eval $merge_tool_cmd )

@@ -158,11 +150,11 @@ run_diff_cmd () {
 
 # Run a either a configured or built-in merge tool
 run_merge_cmd () {
-	merge_tool_cmd="$(get_merge_tool_cmd "$1")"
+	merge_tool_cmd=$(get_merge_tool_cmd "$1")
 	if test -n "$merge_tool_cmd"
 	then
-		trust_exit_code="$(git config --bool \
-			mergetool."$1".trustExitCode || echo false)"
+		trust_exit_code=$(git config --bool \
+			"mergetool.$1.trustExitCode" || echo false)
 		if test "$trust_exit_code" = "false"
 		then
 			touch "$BACKUP"

@@ -253,7 +245,7 @@ guess_merge_tool () {
 	# Loop over each candidate and stop when a valid merge tool is found.
 	for i in $tools
 	do
-		merge_tool_path="$(translate_merge_tool_path "$i")"
+		merge_tool_path=$(translate_merge_tool_path "$i")
 		if type "$merge_tool_path" >/dev/null 2>&1
 		then
 			echo "$i"

@@ -300,9 +292,9 @@ get_merge_tool_path () {
 	fi
 	if test -z "$merge_tool_path"
 	then
-		merge_tool_path="$(translate_merge_tool_path "$merge_tool")"
+		merge_tool_path=$(translate_merge_tool_path "$merge_tool")
 	fi
-	if test -z "$(get_merge_tool_cmd "$merge_tool")" &&
+	if test -z $(get_merge_tool_cmd "$merge_tool") &&
 		! type "$merge_tool_path" >/dev/null 2>&1
 	then
 		echo >&2 "The $TOOL_MODE tool $merge_tool is not available as"\

@@ -314,11 +306,11 @@ get_merge_tool_path () {
 
 get_merge_tool () {
 	# Check if a merge tool has been configured
-	merge_tool="$(get_configured_merge_tool)"
+	merge_tool=$(get_configured_merge_tool)
 	# Try to guess an appropriate merge tool if no tool has been set.
 	if test -z "$merge_tool"
 	then
-		merge_tool="$(guess_merge_tool)" || exit
+		merge_tool=$(guess_merge_tool) || exit
 	fi
 	echo "$merge_tool"
 }

@@ -240,7 +240,14 @@ show_tool_help () {
 
 guess_merge_tool () {
 	list_merge_tool_candidates
-	echo >&2 "merge tool candidates: $tools"
+	msg="\
+
+This message is displayed because '$TOOL_MODE.tool' is not configured.
+See 'git ${TOOL_MODE}tool --tool-help' or 'git help config' for more details.
+'git ${TOOL_MODE}tool' will now attempt to use one of the following tools:
+$tools
+"
+	printf "$msg" >&2
 
 	# Loop over each candidate and stop when a valid merge tool is found.
 	for i in $tools

@@ -9,4 +9,5 @@ gitman.info
 howto-index.txt
 doc.dep
 cmds-*.txt
+mergetools-*.txt
 manpage-base-url.xsl

@@ -226,13 +226,27 @@ cmd-list.made: cmd-list.perl ../command-list.txt $(MAN1_TXT)
 	$(PERL_PATH) ./cmd-list.perl ../command-list.txt $(QUIET_STDERR) && \
 	date >$@
 
+mergetools_txt = mergetools-diff.txt mergetools-merge.txt
+
+$(mergetools_txt): mergetools-list.made
+
+mergetools-list.made: ../git-mergetool--lib.sh $(wildcard ../mergetools/*)
+	$(QUIET_GEN)$(RM) $@ && \
+	$(SHELL_PATH) -c 'MERGE_TOOLS_DIR=../mergetools && \
+		. ../git-mergetool--lib.sh && \
+		filter_tools can_diff "* "' > mergetools-diff.txt && \
+	$(SHELL_PATH) -c 'MERGE_TOOLS_DIR=../mergetools && \
+		. ../git-mergetool--lib.sh && \
+		filter_tools can_merge "* "' > mergetools-merge.txt && \
+	date > $@
+
 clean:
 	$(RM) *.xml *.xml+ *.html *.html+ *.1 *.5 *.7
 	$(RM) *.texi *.texi+ *.texi++ git.info gitman.info
 	$(RM) *.pdf
 	$(RM) howto-index.txt howto/*.html doc.dep
 	$(RM) technical/api-*.html technical/api-index.txt
-	$(RM) $(cmds_txt) *.made
+	$(RM) $(cmds_txt) $(mergetools_txt) *.made
 	$(RM) manpage-base-url.xsl
 
 $(MAN_HTML): %.html : %.txt

@@ -132,9 +132,10 @@ diff.<driver>.cachetextconv::
 	conversion outputs.  See linkgit:gitattributes[5] for details.
 
 diff.tool::
-	The diff tool to be used by linkgit:git-difftool[1].  This
-	option overrides `merge.tool`, and has the same valid built-in
-	values as `merge.tool` minus "tortoisemerge" and plus
-	"kompare".  Any other value is treated as a custom diff tool,
-	and there must be a corresponding `difftool.<tool>.cmd`
-	option.
+	Controls which diff tool is used by linkgit:git-difftool[1].
+	This variable overrides the value configured in `merge.tool`.
+	The list below shows the valid built-in values.
+	Any other value is treated as a custom diff tool and requires
+	that a corresponding difftool.<tool>.cmd variable is defined.
+
+include::mergetools-diff.txt[]

@@ -52,12 +52,12 @@ merge.stat::
 	at the end of the merge.  True by default.
 
 merge.tool::
-	Controls which merge resolution program is used by
-	linkgit:git-mergetool[1].  Valid built-in values are: "araxis",
-	"bc3", "diffuse", "ecmerge", "emerge", "gvimdiff", "kdiff3", "meld",
-	"opendiff", "p4merge", "tkdiff", "tortoisemerge", "vimdiff"
-	and "xxdiff".  Any other value is treated is custom merge tool
-	and there must be a corresponding mergetool.<tool>.cmd option.
+	Controls which merge tool is used by linkgit:git-mergetool[1].
+	The list below shows the valid built-in values.
+	Any other value is treated as a custom merge tool and requires
+	that a corresponding mergetool.<tool>.cmd variable is defined.
+
+include::mergetools-merge.txt[]
 
 merge.verbosity::
 	Controls the amount of output shown by the recursive merge

@@ -1,5 +1,6 @@
 #!/bin/sh
 # git-mergetool--lib is a library for common merge tool functions
+test -z "$MERGE_TOOLS_DIR" &&
 MERGE_TOOLS_DIR=$(git --exec-path)/mergetools
 
 mode_ok () {

@@ -2,6 +2,33 @@
 # git-mergetool--lib is a library for common merge tool functions
 MERGE_TOOLS_DIR=$(git --exec-path)/mergetools
 
+mode_ok () {
+	diff_mode && can_diff ||
+	merge_mode && can_merge
+}
+
+is_available () {
+	merge_tool_path=$(translate_merge_tool_path "$1") &&
+	type "$merge_tool_path" >/dev/null 2>&1
+}
+
+filter_tools () {
+	filter="$1"
+	prefix="$2"
+	(
+		cd "$MERGE_TOOLS_DIR" &&
+		for i in *
+		do
+			echo "$i"
+		done
+	) | sort | while read tool
+	do
+		setup_tool "$tool" 2>/dev/null &&
+		(eval "$filter" "$tool") &&
+		printf "$prefix$tool\n"
+	done
+}
+
 diff_mode() {
 	test "$TOOL_MODE" = diff
 }

@@ -199,27 +226,13 @@ list_merge_tool_candidates () {
 }
 
 show_tool_help () {
-	unavailable= available= LF='
-'
-	for i in "$MERGE_TOOLS_DIR"/*
-	do
-		tool=$(basename "$i")
-		setup_tool "$tool" 2>/dev/null || continue
-
-		merge_tool_path=$(translate_merge_tool_path "$tool")
-		if type "$merge_tool_path" >/dev/null 2>&1
-		then
-			available="$available$tool$LF"
-		else
-			unavailable="$unavailable$tool$LF"
-		fi
-	done
-
 	cmd_name=${TOOL_MODE}tool
+	available=$(filter_tools 'mode_ok && is_available' '\t\t')
+	unavailable=$(filter_tools 'mode_ok && ! is_available' '\t\t')
 	if test -n "$available"
 	then
 		echo "'git $cmd_name --tool=<tool>' may be set to one of the following:"
-		echo "$available" | sort | sed -e 's/^/	/'
+		printf "$available"
 	else
 		echo "No suitable tool for 'git $cmd_name --tool=<tool>' found."
 	fi

@@ -227,7 +240,7 @@ show_tool_help () {
 	then
 		echo
 		echo 'The following tools are valid, but not currently available:'
-		echo "$unavailable" | sort | sed -e 's/^/	/'
+		printf "$unavailable"
 	fi
 	if test -n "$unavailable$available"
 	then

@@ -250,17 +263,12 @@ $tools
 	printf "$msg" >&2
 
 	# Loop over each candidate and stop when a valid merge tool is found.
-	for i in $tools
+	for tool in $tools
 	do
-		merge_tool_path=$(translate_merge_tool_path "$i")
-		if type "$merge_tool_path" >/dev/null 2>&1
-		then
-			echo "$i"
-			return 0
-		fi
+		is_available "$tool" && echo "$tool" && return 0
 	done
 
-	echo >&2 "No known merge resolution program available."
+	echo >&2 "No known ${TOOL_MODE} tool is available."
 	return 1
 }