Merge branch 'jk/diff-no-index-initialize'

"git diff --no-index" may still want to access Git goodies like
--ext-diff and --textconv, but so far these have been ignored,
which has been corrected.

* jk/diff-no-index-initialize:
  diff: reuse diff setup for --no-index case

builtin/diff.c

@@ -338,21 +338,23 @@ int cmd_diff(int argc, const char **argv, const char *prefix)
 		       "--no-index" : "[--no-index]");
 
 	}
-	if (no_index)
-		/* If this is a no-index diff, just run it and exit there. */
-		diff_no_index(the_repository, &rev, argc, argv);
-
-	/* Otherwise, we are doing the usual "git" diff */
-	rev.diffopt.skip_stat_unmatch = !!diff_auto_refresh_index;
 
-	/* Scale to real terminal size and respect statGraphWidth config */
+	/* Set up defaults that will apply to both no-index and regular diffs. */
 	rev.diffopt.stat_width = -1;
 	rev.diffopt.stat_graph_width = -1;
-
-	/* Default to let external and textconv be used */
 	rev.diffopt.flags.allow_external = 1;
 	rev.diffopt.flags.allow_textconv = 1;
 
+	/* If this is a no-index diff, just run it and exit there. */
+	if (no_index)
+		diff_no_index(&rev, argc, argv);
+
+	/*
+	 * Otherwise, we are doing the usual "git" diff; set up any
+	 * further defaults that apply to regular diffs.
+	 */
+	rev.diffopt.skip_stat_unmatch = !!diff_auto_refresh_index;
+
 	/*
 	 * Default to intent-to-add entries invisible in the
 	 * index. This makes them show up as new files in diff-files

diff-no-index.c

@@ -233,20 +233,14 @@ static void fixup_paths(const char **path, struct strbuf *replacement)
 	}
 }
 
-void diff_no_index(struct repository *r,
-		   struct rev_info *revs,
+void diff_no_index(struct rev_info *revs,
 		   int argc, const char **argv)
 {
 	int i;
 	const char *paths[2];
 	struct strbuf replacement = STRBUF_INIT;
 	const char *prefix = revs->prefix;
 
-	/*
-	 * FIXME: --no-index should not look at index and we should be
-	 * able to pass NULL repo. Maybe later.
-	 */
-	repo_diff_setup(r, &revs->diffopt);
 	for (i = 1; i < argc - 2; ) {
 		int j;
 		if (!strcmp(argv[i], "--no-index"))

diff.h

@@ -438,7 +438,7 @@ int diff_flush_patch_id(struct diff_options *, struct object_id *, int);
 
 int diff_result_code(struct diff_options *, int);
 
-void diff_no_index(struct repository *, struct rev_info *, int, const char **);
+void diff_no_index(struct rev_info *, int, const char **);
 
 int index_differs_from(struct repository *r, const char *def,
 		       const struct diff_flags *flags,

t/t4053-diff-no-index.sh

@@ -137,4 +137,12 @@ test_expect_success 'diff --no-index from repo subdir with absolute paths' '
 	test_cmp expect actual
 '
 
+test_expect_success 'diff --no-index allows external diff' '
+	test_expect_code 1 \
+		env GIT_EXTERNAL_DIFF="echo external ;:" \
+		git diff --no-index non/git/a non/git/b >actual &&
+	echo external >expect &&
+	test_cmp expect actual
+'
+
 test_done