Use correct grammar in diffstat summary line

"git diff --stat" and "git apply --stat" now learn to print the line
"%d files changed, %d insertions(+), %d deletions(-)" in singular form
whenever applicable. "0 insertions" and "0 deletions" are also omitted
unless they are both zero.

This matches how versions of "diffstat" that are not prehistoric produced
their output, and also makes this line translatable.

[jc: with help from Thomas Dickey in archaeology of "diffstat"]
[jc: squashed Jonathan's updates to illustrations in tutorials and a test]

Signed-off-by: Nguyễn Thái Ngọc Duy <[email protected]>
Signed-off-by: Jonathan Nieder <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: pclouds

Documentation/gitcore-tutorial.txt

@@ -1004,7 +1004,7 @@ Updating from ae3a2da... to a80b4aa....
 Fast-forward (no commit created; -m option ignored)
  example |    1 +
  hello   |    1 +
- 2 files changed, 2 insertions(+), 0 deletions(-)
+ 2 files changed, 2 insertions(+)
 ----------------
 
 Because your branch did not contain anything more than what had

Documentation/gittutorial-2.txt

@@ -34,12 +34,12 @@ $ echo 'hello world' > file.txt
 $ git add .
 $ git commit -a -m "initial commit"
 [master (root-commit) 54196cc] initial commit
- 1 files changed, 1 insertions(+), 0 deletions(-)
+ 1 file changed, 1 insertion(+)
  create mode 100644 file.txt
 $ echo 'hello world!' >file.txt
 $ git commit -a -m "add emphasis"
 [master c4d59f3] add emphasis
- 1 files changed, 1 insertions(+), 1 deletions(-)
+ 1 file changed, 1 insertion(+), 1 deletion(-)
 ------------------------------------------------
 
 What are the 7 digits of hex that git responded to the commit with?

builtin/apply.c

@@ -14,6 +14,7 @@
 #include "builtin.h"
 #include "string-list.h"
 #include "dir.h"
+#include "diff.h"
 #include "parse-options.h"
 
 /*
@@ -3241,7 +3242,7 @@ static void stat_patch_list(struct patch *patch)
 		show_stats(patch);
 	}
 
-	printf(" %d files changed, %d insertions(+), %d deletions(-)\n", files, adds, dels);
+	print_stat_summary(stdout, files, adds, dels);
 }
 
 static void numstat_patch_list(struct patch *patch)

diff.c

@@ -1322,6 +1322,55 @@ static void fill_print_name(struct diffstat_file *file)
 	file->print_name = pname;
 }
 
+int print_stat_summary(FILE *fp, int files, int insertions, int deletions)
+{
+	struct strbuf sb = STRBUF_INIT;
+	int ret;
+
+	if (!files) {
+		assert(insertions == 0 && deletions == 0);
+		return fputs(_(" 0 files changed\n"), fp);
+	}
+
+	strbuf_addf(&sb,
+		    Q_(" %d file changed", " %d files changed", files),
+		    files);
+
+	/*
+	 * For binary diff, the caller may want to print "x files
+	 * changed" with insertions == 0 && deletions == 0.
+	 *
+	 * Not omitting "0 insertions(+), 0 deletions(-)" in this case
+	 * is probably less confusing (i.e skip over "2 files changed
+	 * but nothing about added/removed lines? Is this a bug in Git?").
+	 */
+	if (insertions || deletions == 0) {
+		/*
+		 * TRANSLATORS: "+" in (+) is a line addition marker;
+		 * do not translate it.
+		 */
+		strbuf_addf(&sb,
+			    Q_(", %d insertion(+)", ", %d insertions(+)",
+			       insertions),
+			    insertions);
+	}
+
+	if (deletions || insertions == 0) {
+		/*
+		 * TRANSLATORS: "-" in (-) is a line removal marker;
+		 * do not translate it.
+		 */
+		strbuf_addf(&sb,
+			    Q_(", %d deletion(-)", ", %d deletions(-)",
+			       deletions),
+			    deletions);
+	}
+	strbuf_addch(&sb, '\n');
+	ret = fputs(sb.buf, fp);
+	strbuf_release(&sb);
+	return ret;
+}
+
 static void show_stats(struct diffstat_t *data, struct diff_options *options)
 {
 	int i, len, add, del, adds = 0, dels = 0;
@@ -1475,9 +1524,7 @@ static void show_stats(struct diffstat_t *data, struct diff_options *options)
 		extra_shown = 1;
 	}
 	fprintf(options->file, "%s", line_prefix);
-	fprintf(options->file,
-	       " %d files changed, %d insertions(+), %d deletions(-)\n",
-	       total_files, adds, dels);
+	print_stat_summary(options->file, total_files, adds, dels);
 }
 
 static void show_shortstats(struct diffstat_t *data, struct diff_options *options)
@@ -1507,8 +1554,7 @@ static void show_shortstats(struct diffstat_t *data, struct diff_options *option
 				options->output_prefix_data);
 		fprintf(options->file, "%s", msg->buf);
 	}
-	fprintf(options->file, " %d files changed, %d insertions(+), %d deletions(-)\n",
-	       total_files, adds, dels);
+	print_stat_summary(options->file, total_files, adds, dels);
 }
 
 static void show_numstat(struct diffstat_t *data, struct diff_options *options)

diff.h

@@ -324,4 +324,7 @@ extern struct userdiff_driver *get_textconv(struct diff_filespec *one);
 
 extern int parse_rename_score(const char **cp_p);
 
+extern int print_stat_summary(FILE *fp, int files,
+			      int insertions, int deletions);
+
 #endif /* DIFF_H */

t/t1200-tutorial.sh

@@ -156,7 +156,7 @@ Updating VARIABLE..VARIABLE
 FASTFORWARD (no commit created; -m option ignored)
  example |    1 +
  hello   |    1 +
- 2 files changed, 2 insertions(+), 0 deletions(-)
+ 2 files changed, 2 insertions(+)
 EOF
 
 test_expect_success 'git resolve' '

t/t3300-funny-names.sh

@@ -167,7 +167,7 @@ test_expect_success TABS_IN_FILENAMES 'git diff-tree delete with-funny' \
 test_expect_success TABS_IN_FILENAMES 'setup expect' '
 cat >expected <<\EOF
  "tabs\t,\" (dq) and spaces"
- 1 files changed, 0 insertions(+), 0 deletions(-)
+ 1 file changed, 0 insertions(+), 0 deletions(-)
 EOF
 '
 

t/t3508-cherry-pick-many-commits.sh

@@ -38,13 +38,13 @@ test_expect_success 'cherry-pick first..fourth works' '
 	cat <<-\EOF >expected &&
 	[master OBJID] second
 	 Author: A U Thor <[email protected]>
-	 1 files changed, 1 insertions(+), 0 deletions(-)
+	 1 file changed, 1 insertion(+)
 	[master OBJID] third
 	 Author: A U Thor <[email protected]>
-	 1 files changed, 1 insertions(+), 0 deletions(-)
+	 1 file changed, 1 insertion(+)
 	[master OBJID] fourth
 	 Author: A U Thor <[email protected]>
-	 1 files changed, 1 insertions(+), 0 deletions(-)
+	 1 file changed, 1 insertion(+)
 	EOF
 
 	git checkout -f master &&
@@ -64,15 +64,15 @@ test_expect_success 'cherry-pick --strategy resolve first..fourth works' '
 	Trying simple merge.
 	[master OBJID] second
 	 Author: A U Thor <[email protected]>
-	 1 files changed, 1 insertions(+), 0 deletions(-)
+	 1 file changed, 1 insertion(+)
 	Trying simple merge.
 	[master OBJID] third
 	 Author: A U Thor <[email protected]>
-	 1 files changed, 1 insertions(+), 0 deletions(-)
+	 1 file changed, 1 insertion(+)
 	Trying simple merge.
 	[master OBJID] fourth
 	 Author: A U Thor <[email protected]>
-	 1 files changed, 1 insertions(+), 0 deletions(-)
+	 1 file changed, 1 insertion(+)
 	EOF
 
 	git checkout -f master &&

t/t3903-stash.sh

@@ -444,7 +444,7 @@ test_expect_success 'stash show - stashes on stack, stash-like argument' '
 	git reset --hard &&
 	cat >expected <<-EOF &&
 	 file |    1 +
-	 1 files changed, 1 insertions(+), 0 deletions(-)
+	 1 file changed, 1 insertion(+)
 	EOF
 	git stash show ${STASH_ID} >actual &&
 	test_cmp expected actual
@@ -482,7 +482,7 @@ test_expect_success 'stash show - no stashes on stack, stash-like argument' '
 	git reset --hard &&
 	cat >expected <<-EOF &&
 	 file |    1 +
-	 1 files changed, 1 insertions(+), 0 deletions(-)
+	 1 file changed, 1 insertion(+)
 	EOF
 	git stash show ${STASH_ID} >actual &&
 	test_cmp expected actual

t/t4013/diff.diff-tree_--cc_--patch-with-stat_--summary_master

@@ -2,7 +2,7 @@ $ git diff-tree --cc --patch-with-stat --summary master
 59d314ad6f356dd08601a4cd5e530381da3e3c64
  dir/sub |    2 ++
  file0   |    3 +++
- 2 files changed, 5 insertions(+), 0 deletions(-)
+ 2 files changed, 5 insertions(+)
 
 diff --cc dir/sub
 index cead32e,7289e35..992913c