git-gui: honor TCLTK_PATH in git-gui--askpass

Since its introduction in 8c76212 (git-gui: Add a simple implementation
of SSH_ASKPASS., 2008-10-15), git-gui--askpass has been calling whatever
wish interpreter is in the path, unlike git-gui.

Correct that by turning it into a script that would be processed at build
time.

Signed-off-by: Carlo Marcelo Arenas Belón <carenas@gmail.com>
Signed-off-by: Johannes Sixt <j6t@kdbg.org>

.gitignore

@@ -4,4 +4,5 @@ git-gui.tcl
 GIT-GUI-BUILD-OPTIONS
 GIT-VERSION-FILE
 git-gui
+git-gui--askpass
 lib/tclIndex

Makefile

@@ -173,10 +173,13 @@ GIT-GUI-BUILD-OPTIONS: FORCE
 	@if grep -q '^[A-Z][A-Z_]*=@.*@$$' $@+; then echo "Unsubstituted build options in $@" >&2 && exit 1; fi
 	@if cmp $@+ $@ >/dev/null 2>&1; then $(RM) $@+; else mv $@+ $@; fi
 
+git-gui--askpass: git-gui--askpass.sh GIT-GUI-BUILD-OPTIONS generate-script.sh
+	$(QUIET_GEN)$(SHELL_PATH) generate-script.sh $@ $< ./GIT-GUI-BUILD-OPTIONS
+
 ifdef GITGUI_WINDOWS_WRAPPER
 all:: git-gui
 endif
-all:: $(GITGUI_MAIN) lib/tclIndex $(ALL_MSGFILES)
+all:: $(GITGUI_MAIN) git-gui--askpass lib/tclIndex $(ALL_MSGFILES)
 
 install: all
 	$(QUIET)$(INSTALL_D0)'$(DESTDIR_SQ)$(gitexecdir_SQ)' $(INSTALL_D1)
@@ -215,7 +218,7 @@ dist-version: GIT-VERSION-FILE
 	@sed 's|^GITGUI_VERSION=||' <GIT-VERSION-FILE  >$(TARDIR)/version
 
 clean::
-	$(RM_RF) $(GITGUI_MAIN) lib/tclIndex po/*.msg $(PO_TEMPLATE)
+	$(RM_RF) $(GITGUI_MAIN) git-gui--askpass lib/tclIndex po/*.msg $(PO_TEMPLATE)
 	$(RM_RF) GIT-VERSION-FILE GIT-GUI-BUILD-OPTIONS
 ifdef GITGUI_WINDOWS_WRAPPER
 	$(RM_RF) git-gui

generate-script.sh

@@ -0,0 +1,22 @@
+#!/bin/sh
+
+set -e
+
+if test $# -ne 3
+then
+	echo >&2 "USAGE: $0 <OUTPUT> <INPUT> <GIT-GUI-BUILD-OPTIONS>"
+	exit 1
+fi
+
+OUTPUT="$1"
+INPUT="$2"
+BUILD_OPTIONS="$3"
+
+. "$BUILD_OPTIONS"
+
+sed \
+	-e "1s|#!.*/sh|#!$SHELL_PATH|" \
+	-e "1,3s|^exec wish|exec '$TCLTK_PATH'|" \
+	"$INPUT" >"$OUTPUT"
+
+chmod a+x "$OUTPUT"

meson.build

@@ -38,14 +38,6 @@ version_file = custom_target(
   build_always_stale: true,
 )
 
-configure_file(
-  input: 'git-gui--askpass',
-  output: 'git-gui--askpass',
-  copy: true,
-  install: true,
-  install_dir: get_option('libexecdir') / 'git-core',
-)
-
 gitgui_main = 'git-gui'
 gitgui_main_install_dir = get_option('libexecdir') / 'git-core'
 
@@ -61,6 +53,20 @@ if target_machine.system() == 'windows'
   )
 endif
 
+custom_target(
+  output: 'git-gui--askpass',
+  input: 'git-gui--askpass.sh',
+  command: [
+    shell,
+    meson.current_source_dir() / 'generate-script.sh',
+    '@OUTPUT@',
+    '@INPUT@',
+    meson.current_build_dir() / 'GIT-GUI-BUILD-OPTIONS',
+  ],
+  install: true,
+  install_dir: get_option('libexecdir') / 'git-core',
+)
+
 custom_target(
   input: 'git-gui.sh',
   output: gitgui_main,