range-diff: fix regression in passing along diff options

In 73a834e9e2 ("range-diff: relieve callers of low-level configuration
burden", 2018-07-22) we broke passing down options like --no-patch,
--stat etc.

Fix that regression, and add a test asserting the pre-73a834e9e2
behavior for some of these diff options.

As noted in a change leading up to this ("range-diff doc: add a
section about output stability", 2018-11-07) the output is not meant
to be stable. So this regression test will likely need to be tweaked
once we get a "proper" --stat option.

See
https://public-inbox.org/git/nycvar.QRO.7.76.6.1811071202480.39@tvgsbejvaqbjf.bet/
for a further explanation of the regression. The fix here is not the
same as in Johannes's on-list patch, for reasons that'll be explained
in a follow-up commit.

The quoting of "EOF" here mirrors that of an earlier test. Perhaps
that should be fixed, but let's leave that up to a later cleanup
change.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

range-diff.c

@@ -433,7 +433,7 @@ int show_range_diff(const char *range1, const char *range2,
 		struct strbuf indent = STRBUF_INIT;
 
 		memcpy(&opts, diffopt, sizeof(opts));
-		opts.output_format = DIFF_FORMAT_PATCH;
+		opts.output_format |= DIFF_FORMAT_PATCH;
 		opts.flags.suppress_diff_headers = 1;
 		opts.flags.dual_color_diffed_diffs = dual_color;
 		opts.output_prefix = output_prefix_cb;

t/t3206-range-diff.sh

@@ -122,6 +122,59 @@ test_expect_success 'changed commit' '
 	test_cmp expected actual
 '
 
+test_expect_success 'changed commit with --no-patch diff option' '
+	git range-diff --no-color --no-patch topic...changed >actual &&
+	cat >expected <<-EOF &&
+	1:  4de457d = 1:  a4b3333 s/5/A/
+	2:  fccce22 = 2:  f51d370 s/4/A/
+	3:  147e64e ! 3:  0559556 s/11/B/
+	4:  a63e992 ! 4:  d966c5c s/12/B/
+	EOF
+	test_cmp expected actual
+'
+
+test_expect_success 'changed commit with --stat diff option' '
+	four_spaces="    " &&
+	git range-diff --no-color --stat topic...changed >actual &&
+	cat >expected <<-EOF &&
+	1:  4de457d = 1:  a4b3333 s/5/A/
+	     a => b | 0
+	     1 file changed, 0 insertions(+), 0 deletions(-)
+	$four_spaces
+	2:  fccce22 = 2:  f51d370 s/4/A/
+	     a => b | 0
+	     1 file changed, 0 insertions(+), 0 deletions(-)
+	$four_spaces
+	3:  147e64e ! 3:  0559556 s/11/B/
+	     a => b | 0
+	     1 file changed, 0 insertions(+), 0 deletions(-)
+	$four_spaces
+	    @@ -10,7 +10,7 @@
+	      9
+	      10
+	     -11
+	    -+B
+	    ++BB
+	      12
+	      13
+	      14
+	4:  a63e992 ! 4:  d966c5c s/12/B/
+	     a => b | 0
+	     1 file changed, 0 insertions(+), 0 deletions(-)
+	$four_spaces
+	    @@ -8,7 +8,7 @@
+	     @@
+	      9
+	      10
+	    - B
+	    + BB
+	     -12
+	     +B
+	      13
+	EOF
+	test_cmp expected actual
+'
+
 test_expect_success 'changed message' '
 	git range-diff --no-color topic...changed-message >actual &&
 	sed s/Z/\ /g >expected <<-EOF &&