Merge branch 'mh/diff-indent-heuristic'

Output from "git diff" can be made easier to read by selecting
which lines are common and which lines are added/deleted
intelligently when the lines before and after the changed section
are the same.  A command line option is added to help with the
experiment to find a good heuristics.

* mh/diff-indent-heuristic:
  blame: honor the diff heuristic options and config
  parse-options: add parse_opt_unknown_cb()
  diff: improve positioning of add/delete blocks in diffs
  xdl_change_compact(): introduce the concept of a change group
  recs_match(): take two xrecord_t pointers as arguments
  is_blank_line(): take a single xrecord_t as argument
  xdl_change_compact(): only use heuristic if group can't be matched
  xdl_change_compact(): fix compaction heuristic to adjust ixo

1 files changed, 216 insertions, 0 deletions

diff --git a/t/t4061-diff-indent.sh b/t/t4061-diff-indent.sh
new file mode 100755
index 000000000..556450609
--- /dev/null
+++ b/t/t4061-diff-indent.sh
@@ -0,0 +1,216 @@
+#!/bin/sh
+
+test_description='Test diff indent heuristic.
+
+'
+. ./test-lib.sh
+. "$TEST_DIRECTORY"/diff-lib.sh
+
+# Compare two diff outputs. Ignore "index" lines, because we don't
+# care about SHA-1s or file modes.
+compare_diff () {
+	sed -e "/^index /d" <"$1" >.tmp-1
+	sed -e "/^index /d" <"$2" >.tmp-2
+	test_cmp .tmp-1 .tmp-2 && rm -f .tmp-1 .tmp-2
+}
+
+# Compare blame output using the expectation for a diff as reference.
+# Only look for the lines coming from non-boundary commits.
+compare_blame () {
+	sed -n -e "1,4d" -e "s/^\+//p" <"$1" >.tmp-1
+	sed -ne "s/^[^^][^)]*) *//p" <"$2" >.tmp-2
+	test_cmp .tmp-1 .tmp-2 && rm -f .tmp-1 .tmp-2
+}
+
+test_expect_success 'prepare' '
+	cat <<-\EOF >spaces.txt &&
+	1
+	2
+	a
+
+	b
+	3
+	4
+	EOF
+
+	cat <<-\EOF >functions.c &&
+	1
+	2
+	/* function */
+	foo() {
+	    foo
+	}
+
+	3
+	4
+	EOF
+
+	git add spaces.txt functions.c &&
+	test_tick &&
+	git commit -m initial &&
+	git branch old &&
+
+	cat <<-\EOF >spaces.txt &&
+	1
+	2
+	a
+
+	b
+	a
+
+	b
+	3
+	4
+	EOF
+
+	cat <<-\EOF >functions.c &&
+	1
+	2
+	/* function */
+	bar() {
+	    foo
+	}
+
+	/* function */
+	foo() {
+	    foo
+	}
+
+	3
+	4
+	EOF
+
+	git add spaces.txt functions.c &&
+	test_tick &&
+	git commit -m initial &&
+	git branch new &&
+
+	tr "_" " " <<-\EOF >spaces-expect &&
+	diff --git a/spaces.txt b/spaces.txt
+	--- a/spaces.txt
+	+++ b/spaces.txt
+	@@ -3,5 +3,8 @@
+	 a
+	_
+	 b
+	+a
+	+
+	+b
+	 3
+	 4
+	EOF
+
+	tr "_" " " <<-\EOF >spaces-compacted-expect &&
+	diff --git a/spaces.txt b/spaces.txt
+	--- a/spaces.txt
+	+++ b/spaces.txt
+	@@ -2,6 +2,9 @@
+	 2
+	 a
+	_
+	+b
+	+a
+	+
+	 b
+	 3
+	 4
+	EOF
+
+	tr "_" " " <<-\EOF >functions-expect &&
+	diff --git a/functions.c b/functions.c
+	--- a/functions.c
+	+++ b/functions.c
+	@@ -1,6 +1,11 @@
+	 1
+	 2
+	 /* function */
+	+bar() {
+	+    foo
+	+}
+	+
+	+/* function */
+	 foo() {
+	     foo
+	 }
+	EOF
+
+	tr "_" " " <<-\EOF >functions-compacted-expect
+	diff --git a/functions.c b/functions.c
+	--- a/functions.c
+	+++ b/functions.c
+	@@ -1,5 +1,10 @@
+	 1
+	 2
+	+/* function */
+	+bar() {
+	+    foo
+	+}
+	+
+	 /* function */
+	 foo() {
+	     foo
+	EOF
+'
+
+test_expect_success 'diff: ugly spaces' '
+	git diff old new -- spaces.txt >out &&
+	compare_diff spaces-expect out
+'
+
+test_expect_success 'diff: nice spaces with --indent-heuristic' '
+	git diff --indent-heuristic old new -- spaces.txt >out-compacted &&
+	compare_diff spaces-compacted-expect out-compacted
+'
+
+test_expect_success 'diff: nice spaces with diff.indentHeuristic' '
+	git -c diff.indentHeuristic=true diff old new -- spaces.txt >out-compacted2 &&
+	compare_diff spaces-compacted-expect out-compacted2
+'
+
+test_expect_success 'diff: --no-indent-heuristic overrides config' '
+	git -c diff.indentHeuristic=true diff --no-indent-heuristic old new -- spaces.txt >out2 &&
+	compare_diff spaces-expect out2
+'
+
+test_expect_success 'diff: --indent-heuristic with --patience' '
+	git diff --indent-heuristic --patience old new -- spaces.txt >out-compacted3 &&
+	compare_diff spaces-compacted-expect out-compacted3
+'
+
+test_expect_success 'diff: --indent-heuristic with --histogram' '
+	git diff --indent-heuristic --histogram old new -- spaces.txt >out-compacted4 &&
+	compare_diff spaces-compacted-expect out-compacted4
+'
+
+test_expect_success 'diff: ugly functions' '
+	git diff old new -- functions.c >out &&
+	compare_diff functions-expect out
+'
+
+test_expect_success 'diff: nice functions with --indent-heuristic' '
+	git diff --indent-heuristic old new -- functions.c >out-compacted &&
+	compare_diff functions-compacted-expect out-compacted
+'
+
+test_expect_success 'blame: ugly spaces' '
+	git blame old..new -- spaces.txt >out-blame &&
+	compare_blame spaces-expect out-blame
+'
+
+test_expect_success 'blame: nice spaces with --indent-heuristic' '
+	git blame --indent-heuristic old..new -- spaces.txt >out-blame-compacted &&
+	compare_blame spaces-compacted-expect out-blame-compacted
+'
+
+test_expect_success 'blame: nice spaces with diff.indentHeuristic' '
+	git -c diff.indentHeuristic=true blame old..new -- spaces.txt >out-blame-compacted2 &&
+	compare_blame spaces-compacted-expect out-blame-compacted2
+'
+
+test_expect_success 'blame: --no-indent-heuristic overrides config' '
+	git -c diff.indentHeuristic=true blame --no-indent-heuristic old..new -- spaces.txt >out-blame2 &&
+	git blame old..new -- spaces.txt >out-blame &&
+	compare_blame spaces-expect out-blame2
+'
+
+test_done