Merge branch 'ab/range-diff-no-patch'

The "--no-patch" option, which can be used to get a high-level
overview without the actual line-by-line patch difference shown, of
the "range-diff" command was earlier broken, which has been
corrected.

* ab/range-diff-no-patch:
  range-diff: make diff option behavior (e.g. --stat) consistent
  range-diff: fix regression in passing along diff options
  range-diff doc: add a section about output stability

3 files changed, 49 insertions, 1 deletions

diff --git a/Documentation/git-range-diff.txt b/Documentation/git-range-diff.txt
index f693930fdb..8a6ea2c6c5 100644
--- a/Documentation/git-range-diff.txt
+++ b/Documentation/git-range-diff.txt
@@ -78,6 +78,23 @@ between patches", i.e. to compare the author, commit message and diff of
 corresponding old/new commits. There is currently no means to tweak the
 diff options passed to `git log` when generating those patches.
 
+OUTPUT STABILITY
+----------------
+
+The output of the `range-diff` command is subject to change. It is
+intended to be human-readable porcelain output, not something that can
+be used across versions of Git to get a textually stable `range-diff`
+(as opposed to something like the `--stable` option to
+linkgit:git-patch-id[1]). There's also no equivalent of
+linkgit:git-apply[1] for `range-diff`, the output is not intended to
+be machine-readable.
+
+This is particularly true when passing in diff options. Currently some
+options like `--stat` can, as an emergent effect, produce output
+that's quite useless in the context of `range-diff`. Future versions
+of `range-diff` may learn to interpret such options in a manner
+specific to `range-diff` (e.g. for `--stat` producing human-readable
+output which summarizes how the diffstat changed).
 
 CONFIGURATION
 -------------
diff --git a/range-diff.c b/range-diff.c
index 3958720f00..767af8c5bb 100644
--- a/range-diff.c
+++ b/range-diff.c
@@ -461,7 +461,8 @@ 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;
+		if (!opts.output_format)
+			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;
diff --git a/t/t3206-range-diff.sh b/t/t3206-range-diff.sh
index 6aae364171..e497c1358f 100755
--- a/t/t3206-range-diff.sh
+++ b/t/t3206-range-diff.sh
@@ -122,6 +122,36 @@ 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' '
+	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(-)
+	2:  fccce22 = 2:  f51d370 s/4/A/
+	     a => b | 0
+	     1 file changed, 0 insertions(+), 0 deletions(-)
+	3:  147e64e ! 3:  0559556 s/11/B/
+	     a => b | 0
+	     1 file changed, 0 insertions(+), 0 deletions(-)
+	4:  a63e992 ! 4:  d966c5c s/12/B/
+	     a => b | 0
+	     1 file changed, 0 insertions(+), 0 deletions(-)
+	EOF
+	test_cmp expected actual
+'
+
 test_expect_success 'changed commit with sm config' '
 	git range-diff --no-color --submodule=log topic...changed >actual &&
 	cat >expected <<-EOF &&