Merge branch 'ar/diff-args-osx-precompose' into maint

Many commands normalize command line arguments from NFD to NFC
variant of UTF-8 on OSX, but commands in the "diff" family did
not, causing "git diff $path" to complain that no such path is
known to Git.  They have been taught to do the normalization.

* ar/diff-args-osx-precompose:
  diff: run arguments through precompose_argv

builtin/diff-files.c

@@ -24,6 +24,7 @@ int cmd_diff_files(int argc, const char **argv, const char *prefix)
 	gitmodules_config();
 	git_config(git_diff_basic_config, NULL); /* no "diff" UI options */
 	rev.abbrev = 0;
+	precompose_argv(argc, argv);
 
 	argc = setup_revisions(argc, argv, &rev, NULL);
 	while (1 < argc && argv[1][0] == '-') {

builtin/diff-index.c

@@ -21,6 +21,7 @@ int cmd_diff_index(int argc, const char **argv, const char *prefix)
 	gitmodules_config();
 	git_config(git_diff_basic_config, NULL); /* no "diff" UI options */
 	rev.abbrev = 0;
+	precompose_argv(argc, argv);
 
 	argc = setup_revisions(argc, argv, &rev, NULL);
 	for (i = 1; i < argc; i++) {

builtin/diff-tree.c

@@ -114,6 +114,8 @@ int cmd_diff_tree(int argc, const char **argv, const char *prefix)
 	opt->disable_stdin = 1;
 	memset(&s_r_opt, 0, sizeof(s_r_opt));
 	s_r_opt.tweak = diff_tree_tweak_rev;
+
+	precompose_argv(argc, argv);
 	argc = setup_revisions(argc, argv, opt, &s_r_opt);
 
 	while (--argc > 0) {

builtin/diff.c

@@ -319,6 +319,7 @@ int cmd_diff(int argc, const char **argv, const char *prefix)
 	if (!no_index)
 		gitmodules_config();
 	git_config(git_diff_ui_config, NULL);
+	precompose_argv(argc, argv);
 
 	init_revisions(&rev, prefix);
 

t/t3910-mac-os-precompose.sh

@@ -49,12 +49,54 @@ test_expect_success "setup" '
 test_expect_success "setup case mac" '
 	git checkout -b mac_os
 '
+# This will test nfd2nfc in git diff
+test_expect_success "git diff f.Adiar" '
+	touch f.$Adiarnfc &&
+	git add f.$Adiarnfc &&
+	echo f.Adiarnfc >f.$Adiarnfc &&
+	git diff f.$Adiarnfd >expect &&
+	git diff f.$Adiarnfc >actual &&
+	test_cmp expect actual &&
+	git reset HEAD f.Adiarnfc &&
+	rm f.$Adiarnfc expect actual
+'
+# This will test nfd2nfc in git diff-files
+test_expect_success "git diff-files f.Adiar" '
+	touch f.$Adiarnfc &&
+	git add f.$Adiarnfc &&
+	echo f.Adiarnfc >f.$Adiarnfc &&
+	git diff-files f.$Adiarnfd >expect &&
+	git diff-files f.$Adiarnfc >actual &&
+	test_cmp expect actual &&
+	git reset HEAD f.Adiarnfc &&
+	rm f.$Adiarnfc expect actual
+'
+# This will test nfd2nfc in git diff-index
+test_expect_success "git diff-index f.Adiar" '
+	touch f.$Adiarnfc &&
+	git add f.$Adiarnfc &&
+	echo f.Adiarnfc >f.$Adiarnfc &&
+	git diff-index HEAD f.$Adiarnfd >expect &&
+	git diff-index HEAD f.$Adiarnfc >actual &&
+	test_cmp expect actual &&
+	git reset HEAD f.Adiarnfc &&
+	rm f.$Adiarnfc expect actual
+'
 # This will test nfd2nfc in readdir()
 test_expect_success "add file Adiarnfc" '
 	echo f.Adiarnfc >f.$Adiarnfc &&
 	git add f.$Adiarnfc &&
 	git commit -m "add f.$Adiarnfc"
 '
+# This will test nfd2nfc in git diff-tree
+test_expect_success "git diff-tree f.Adiar" '
+	echo f.Adiarnfc >>f.$Adiarnfc &&
+	git diff-tree HEAD f.$Adiarnfd >expect &&
+	git diff-tree HEAD f.$Adiarnfc >actual &&
+	test_cmp expect actual &&
+	git checkout f.$Adiarnfc &&
+	rm expect actual
+'
 # This will test nfd2nfc in git stage()
 test_expect_success "stage file d.Adiarnfd/f.Adiarnfd" '
 	mkdir d.$Adiarnfd &&