Documentation: extract script to generate a list of mergetools

We include the list of available mergetools into our manpages. Extract
the script that performs this logic such that we can reuse it in other
build systems.

While at it, refactor the Makefile targets such that we don't create
"mergetools-list.made" anymore. It shouldn't be necessary, as we can
instead have other targets depend on "mergetools-{diff,merge}.txt"
directly.

Signed-off-by: Patrick Steinhardt <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: pks-t

Documentation/Makefile

@@ -282,11 +282,13 @@ ifneq ($(filter-out lint-docs clean,$(MAKECMDGOALS)),)
 -include ../GIT-VERSION-FILE
 endif
 
+mergetools_txt = mergetools-diff.txt mergetools-merge.txt
+
 #
 # Determine "include::" file references in asciidoc files.
 #
 docdep_prereqs = \
-	mergetools-list.made $(mergetools_txt) \
+	$(mergetools_txt) \
 	cmd-list.made $(cmds_txt)
 
 doc.dep : $(docdep_prereqs) $(DOC_DEP_TXT) build-docdep.perl
@@ -315,19 +317,11 @@ cmd-list.made: cmd-list.perl ../command-list.txt $(MAN1_TXT)
 	$(QUIET_GEN)$(PERL_PATH) ./cmd-list.perl .. . $(cmds_txt) && \
 	date >$@
 
-mergetools_txt = mergetools-diff.txt mergetools-merge.txt
-
-$(mergetools_txt): mergetools-list.made
-
-mergetools-list.made: ../git-mergetool--lib.sh $(wildcard ../mergetools/*)
-	$(QUIET_GEN) \
-	$(SHELL_PATH) -c 'MERGE_TOOLS_DIR=../mergetools && TOOL_MODE=diff && \
-		. ../git-mergetool--lib.sh && \
-		show_tool_names can_diff' | sed -e "s/\([a-z0-9]*\)/\`\1\`;;/" >mergetools-diff.txt && \
-	$(SHELL_PATH) -c 'MERGE_TOOLS_DIR=../mergetools && TOOL_MODE=merge && \
-		. ../git-mergetool--lib.sh && \
-		show_tool_names can_merge' | sed -e "s/\([a-z0-9]*\)/\`\1\`;;/" >mergetools-merge.txt && \
-	date >$@
+mergetools-%.txt: generate-mergetool-list.sh ../git-mergetool--lib.sh $(wildcard ../mergetools/*)
+mergetools-diff.txt:
+	$(QUIET_GEN)$(SHELL_PATH) ./generate-mergetool-list.sh .. diff $@
+mergetools-merge.txt:
+	$(QUIET_GEN)$(SHELL_PATH) ./generate-mergetool-list.sh .. merge $@
 
 TRACK_ASCIIDOCFLAGS = $(subst ','\'',$(ASCIIDOC_COMMON):$(ASCIIDOC_HTML):$(ASCIIDOC_DOCBOOK))
 

Documentation/generate-mergetool-list.sh

@@ -0,0 +1,17 @@
+#!/bin/sh
+
+if test "$#" -ne 3
+then
+	echo >&2 "USAGE: $0 <SOURCE_DIR> <MODE> <OUTPUT>"
+	exit 1
+fi
+
+SOURCE_DIR="$1"
+TOOL_MODE="$2"
+OUTPUT="$3"
+MERGE_TOOLS_DIR="$SOURCE_DIR/mergetools"
+
+(
+	. "$SOURCE_DIR"/git-mergetool--lib.sh &&
+	show_tool_names can_$TOOL_MODE
+) | sed -e "s/\([a-z0-9]*\)/\`\1\`;;/" >"$OUTPUT"