diff: handle --no-abbrev in no-index casejb/diff-no-index-no-abbrev

There are two different places where the --no-abbrev option is parsed,
and two different places where SHA-1s are abbreviated. We normally parse
--no-abbrev with setup_revisions(), but in the no-index case, "git diff"
calls diff_opt_parse() directly, and diff_opt_parse() didn't handle
--no-abbrev until now. (It did handle --abbrev, however.) We normally
abbreviate SHA-1s with find_unique_abbrev(), but commit 4f03666 ("diff:
handle sha1 abbreviations outside of repository, 2016-10-20) recently
introduced a special case when you run "git diff" outside of a
repository.

setup_revisions() does also call diff_opt_parse(), but not for --abbrev
or --no-abbrev, which it handles itself. setup_revisions() sets
rev_info->abbrev, and later copies that to diff_options->abbrev. It
handles --no-abbrev by setting abbrev to zero. (This change doesn't
touch that.)

Setting abbrev to zero was broken in the outside-of-a-repository special
case, which until now resulted in a truly zero-length SHA-1, rather than
taking zero to mean do not abbreviate. The only way to trigger this bug,
however, was by running "git diff --raw" without either the --abbrev or
--no-abbrev options, because 1) without --raw it doesn't respect abbrev
(which is bizarre, but has been that way forever), 2) we silently clamp
--abbrev=0 to MINIMUM_ABBREV, and 3) --no-abbrev wasn't handled until
now.

The outside-of-a-repository case is one of three no-index cases. The
other two are when one of the files you're comparing is outside of the
repository you're in, and the --no-index option.

Signed-off-by: Jack Bates <jack@nottheoilrig.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

8 files changed, 39 insertions, 1 deletions

diff --git a/diff.c b/diff.c
index ec8728362d..84dba60c40 100644
--- a/diff.c
+++ b/diff.c
@@ -3106,7 +3106,8 @@ static const char *diff_abbrev_oid(const struct object_id *oid, int abbrev)
 			abbrev = FALLBACK_DEFAULT_ABBREV;
 		if (abbrev > GIT_SHA1_HEXSZ)
 			die("BUG: oid abbreviation out of range: %d", abbrev);
-		hex[abbrev] = '\0';
+		if (abbrev)
+			hex[abbrev] = '\0';
 		return hex;
 	}
 }
@@ -3364,6 +3365,7 @@ void diff_setup(struct diff_options *options)
 
 	options->file = stdout;
 
+	options->abbrev = DEFAULT_ABBREV;
 	options->line_termination = '\n';
 	options->break_opt = -1;
 	options->rename_limit = -1;
@@ -4024,6 +4026,8 @@ int diff_opt_parse(struct diff_options *options,
 			    offending, optarg);
 		return argcount;
 	}
+	else if (!strcmp(arg, "--no-abbrev"))
+		options->abbrev = 0;
 	else if (!strcmp(arg, "--abbrev"))
 		options->abbrev = DEFAULT_ABBREV;
 	else if (skip_prefix(arg, "--abbrev=", &arg)) {
diff --git a/t/t4013-diff-various.sh b/t/t4013-diff-various.sh
index 566817e2ef..d09acfe48e 100755
--- a/t/t4013-diff-various.sh
+++ b/t/t4013-diff-various.sh
@@ -311,6 +311,13 @@ diff --line-prefix=abc master master^ side
 diff --dirstat master~1 master~2
 diff --dirstat initial rearrange
 diff --dirstat-by-file initial rearrange
+# No-index --abbrev and --no-abbrev
+diff --raw initial
+diff --raw --abbrev=4 initial
+diff --raw --no-abbrev initial
+diff --no-index --raw dir2 dir
+diff --no-index --raw --abbrev=4 dir2 dir
+diff --no-index --raw --no-abbrev dir2 dir
 EOF
 
 test_expect_success 'log -S requires an argument' '
diff --git a/t/t4013/diff.diff_--no-index_--raw_--abbrev=4_dir2_dir b/t/t4013/diff.diff_--no-index_--raw_--abbrev=4_dir2_dir
new file mode 100644
index 0000000000..a71b38a833
--- /dev/null
+++ b/t/t4013/diff.diff_--no-index_--raw_--abbrev=4_dir2_dir
@@ -0,0 +1,3 @@
+$ git diff --no-index --raw --abbrev=4 dir2 dir
+:000000 100644 0000... 0000... A	dir/sub
+$
diff --git a/t/t4013/diff.diff_--no-index_--raw_--no-abbrev_dir2_dir b/t/t4013/diff.diff_--no-index_--raw_--no-abbrev_dir2_dir
new file mode 100644
index 0000000000..e0f00977c8
--- /dev/null
+++ b/t/t4013/diff.diff_--no-index_--raw_--no-abbrev_dir2_dir
@@ -0,0 +1,3 @@
+$ git diff --no-index --raw --no-abbrev dir2 dir
+:000000 100644 0000000000000000000000000000000000000000 0000000000000000000000000000000000000000 A	dir/sub
+$
diff --git a/t/t4013/diff.diff_--no-index_--raw_dir2_dir b/t/t4013/diff.diff_--no-index_--raw_dir2_dir
new file mode 100644
index 0000000000..3cb4ee7a9a
--- /dev/null
+++ b/t/t4013/diff.diff_--no-index_--raw_dir2_dir
@@ -0,0 +1,3 @@
+$ git diff --no-index --raw dir2 dir
+:000000 100644 0000000... 0000000... A	dir/sub
+$
diff --git a/t/t4013/diff.diff_--raw_--abbrev=4_initial b/t/t4013/diff.diff_--raw_--abbrev=4_initial
new file mode 100644
index 0000000000..c3641db31d
--- /dev/null
+++ b/t/t4013/diff.diff_--raw_--abbrev=4_initial
@@ -0,0 +1,6 @@
+$ git diff --raw --abbrev=4 initial
+:100644 100644 35d2... 9929... M	dir/sub
+:100644 100644 01e7... 10a8... M	file0
+:000000 100644 0000... b1e6... A	file1
+:100644 000000 01e7... 0000... D	file2
+$
diff --git a/t/t4013/diff.diff_--raw_--no-abbrev_initial b/t/t4013/diff.diff_--raw_--no-abbrev_initial
new file mode 100644
index 0000000000..c87a1258e3
--- /dev/null
+++ b/t/t4013/diff.diff_--raw_--no-abbrev_initial
@@ -0,0 +1,6 @@
+$ git diff --raw --no-abbrev initial
+:100644 100644 35d242ba79ae89ac695e26b3d4c27a8e6f028f9e 992913c5aa0a5476d10c49ed0f21fc0c6d1aedf3 M	dir/sub
+:100644 100644 01e79c32a8c99c557f0757da7cb6d65b3414466d 10a8a9f3657f91a156b9f0184ed79a20adef9f7f M	file0
+:000000 100644 0000000000000000000000000000000000000000 b1e67221afe8461efd244b487afca22d46b95eb8 A	file1
+:100644 000000 01e79c32a8c99c557f0757da7cb6d65b3414466d 0000000000000000000000000000000000000000 D	file2
+$
diff --git a/t/t4013/diff.diff_--raw_initial b/t/t4013/diff.diff_--raw_initial
new file mode 100644
index 0000000000..a3e978040d
--- /dev/null
+++ b/t/t4013/diff.diff_--raw_initial
@@ -0,0 +1,6 @@
+$ git diff --raw initial
+:100644 100644 35d242b... 992913c... M	dir/sub
+:100644 100644 01e79c3... 10a8a9f... M	file0
+:000000 100644 0000000... b1e6722... A	file1
+:100644 000000 01e79c3... 0000000... D	file2
+$