Merge branch 'dl/diff-merge-base'

"git diff A...B" learned "git diff --merge-base A B", which is a
longer short-hand to say the same thing.

* dl/diff-merge-base:
  contrib/completion: complete `git diff --merge-base`
  builtin/diff-tree: learn --merge-base
  builtin/diff-index: learn --merge-base
  t4068: add --merge-base tests
  diff-lib: define diff_get_merge_base()
  diff-lib: accept option flags in run_diff_index()
  contrib/completion: extract common diff/difftool options
  git-diff.txt: backtick quote command text
  git-diff-index.txt: make --cached description a proper sentence
  t4068: remove unnecessary >tmp

2 files changed, 193 insertions, 91 deletions

diff --git a/t/t4068-diff-symmetric-merge-base.sh b/t/t4068-diff-symmetric-merge-base.sh
new file mode 100755
index 0000000000..03487cc945
--- /dev/null
+++ b/t/t4068-diff-symmetric-merge-base.sh
@@ -0,0 +1,193 @@
+#!/bin/sh
+
+test_description='behavior of diff with symmetric-diff setups and --merge-base'
+
+. ./test-lib.sh
+
+# build these situations:
+#  - normal merge with one merge base (br1...b2r);
+#  - criss-cross merge ie 2 merge bases (br1...master);
+#  - disjoint subgraph (orphan branch, br3...master).
+#
+#     B---E   <-- master
+#    / \ /
+#   A   X
+#    \ / \
+#     C---D--G   <-- br1
+#      \    /
+#       ---F   <-- br2
+#
+#  H  <-- br3
+#
+# We put files into a few commits so that we can verify the
+# output as well.
+
+test_expect_success setup '
+	git commit --allow-empty -m A &&
+	echo b >b &&
+	git add b &&
+	git commit -m B &&
+	git checkout -b br1 HEAD^ &&
+	echo c >c &&
+	git add c &&
+	git commit -m C &&
+	git tag commit-C &&
+	git merge -m D master &&
+	git tag commit-D &&
+	git checkout master &&
+	git merge -m E commit-C &&
+	git checkout -b br2 commit-C &&
+	echo f >f &&
+	git add f &&
+	git commit -m F &&
+	git checkout br1 &&
+	git merge -m G br2 &&
+	git checkout --orphan br3 &&
+	git commit -m H
+'
+
+test_expect_success 'diff with one merge base' '
+	git diff commit-D...br1 >tmp &&
+	tail -n 1 tmp >actual &&
+	echo +f >expect &&
+	test_cmp expect actual
+'
+
+# The output (in tmp) can have +b or +c depending
+# on which merge base (commit B or C) is picked.
+# It should have one of those two, which comes out
+# to seven lines.
+test_expect_success 'diff with two merge bases' '
+	git diff br1...master >tmp 2>err &&
+	test_line_count = 7 tmp &&
+	test_line_count = 1 err
+'
+
+test_expect_success 'diff with no merge bases' '
+	test_must_fail git diff br2...br3 2>err &&
+	test_i18ngrep "fatal: br2...br3: no merge base" err
+'
+
+test_expect_success 'diff with too many symmetric differences' '
+	test_must_fail git diff br1...master br2...br3 2>err &&
+	test_i18ngrep "usage" err
+'
+
+test_expect_success 'diff with symmetric difference and extraneous arg' '
+	test_must_fail git diff master br1...master 2>err &&
+	test_i18ngrep "usage" err
+'
+
+test_expect_success 'diff with two ranges' '
+	test_must_fail git diff master br1..master br2..br3 2>err &&
+	test_i18ngrep "usage" err
+'
+
+test_expect_success 'diff with ranges and extra arg' '
+	test_must_fail git diff master br1..master commit-D 2>err &&
+	test_i18ngrep "usage" err
+'
+
+test_expect_success 'diff --merge-base with no commits' '
+	test_must_fail git diff --merge-base
+'
+
+test_expect_success 'diff --merge-base with three commits' '
+	test_must_fail git diff --merge-base br1 br2 master 2>err &&
+	test_i18ngrep "usage" err
+'
+
+for cmd in diff-index diff
+do
+	test_expect_success "$cmd --merge-base with one commit" '
+		git checkout master &&
+		git $cmd commit-C >expect &&
+		git $cmd --merge-base br2 >actual &&
+		test_cmp expect actual
+	'
+
+	test_expect_success "$cmd --merge-base with one commit and unstaged changes" '
+		git checkout master &&
+		test_when_finished git reset --hard &&
+		echo unstaged >>c &&
+		git $cmd commit-C >expect &&
+		git $cmd --merge-base br2 >actual &&
+		test_cmp expect actual
+	'
+
+	test_expect_success "$cmd --merge-base with one commit and staged and unstaged changes" '
+		git checkout master &&
+		test_when_finished git reset --hard &&
+		echo staged >>c &&
+		git add c &&
+		echo unstaged >>c &&
+		git $cmd commit-C >expect &&
+		git $cmd --merge-base br2 >actual &&
+		test_cmp expect actual
+	'
+
+	test_expect_success "$cmd --merge-base --cached with one commit and staged and unstaged changes" '
+		git checkout master &&
+		test_when_finished git reset --hard &&
+		echo staged >>c &&
+		git add c &&
+		echo unstaged >>c &&
+		git $cmd --cached commit-C >expect &&
+		git $cmd --cached --merge-base br2 >actual &&
+		test_cmp expect actual
+	'
+
+	test_expect_success "$cmd --merge-base with non-commit" '
+		git checkout master &&
+		test_must_fail git $cmd --merge-base master^{tree} 2>err &&
+		test_i18ngrep "fatal: --merge-base only works with commits" err
+	'
+
+	test_expect_success "$cmd --merge-base with no merge bases and one commit" '
+		git checkout master &&
+		test_must_fail git $cmd --merge-base br3 2>err &&
+		test_i18ngrep "fatal: no merge base found" err
+	'
+
+	test_expect_success "$cmd --merge-base with multiple merge bases and one commit" '
+		git checkout master &&
+		test_must_fail git $cmd --merge-base br1 2>err &&
+		test_i18ngrep "fatal: multiple merge bases found" err
+	'
+done
+
+for cmd in diff-tree diff
+do
+	test_expect_success "$cmd --merge-base with two commits" '
+		git $cmd commit-C master >expect &&
+		git $cmd --merge-base br2 master >actual &&
+		test_cmp expect actual
+	'
+
+	test_expect_success "$cmd --merge-base commit and non-commit" '
+		test_must_fail git $cmd --merge-base br2 master^{tree} 2>err &&
+		test_i18ngrep "fatal: --merge-base only works with commits" err
+	'
+
+	test_expect_success "$cmd --merge-base with no merge bases and two commits" '
+		test_must_fail git $cmd --merge-base br2 br3 2>err &&
+		test_i18ngrep "fatal: no merge base found" err
+	'
+
+	test_expect_success "$cmd --merge-base with multiple merge bases and two commits" '
+		test_must_fail git $cmd --merge-base master br1 2>err &&
+		test_i18ngrep "fatal: multiple merge bases found" err
+	'
+done
+
+test_expect_success 'diff-tree --merge-base with one commit' '
+	test_must_fail git diff-tree --merge-base master 2>err &&
+	test_i18ngrep "fatal: --merge-base only works with two commits" err
+'
+
+test_expect_success 'diff --merge-base with range' '
+	test_must_fail git diff --merge-base br2..br3 2>err &&
+	test_i18ngrep "fatal: --merge-base does not work with ranges" err
+'
+
+test_done
diff --git a/t/t4068-diff-symmetric.sh b/t/t4068-diff-symmetric.sh
deleted file mode 100755
index 31d17a5af0..0000000000
--- a/t/t4068-diff-symmetric.sh
+++ /dev/null
@@ -1,91 +0,0 @@
-#!/bin/sh
-
-test_description='behavior of diff with symmetric-diff setups'
-
-. ./test-lib.sh
-
-# build these situations:
-#  - normal merge with one merge base (br1...b2r);
-#  - criss-cross merge ie 2 merge bases (br1...master);
-#  - disjoint subgraph (orphan branch, br3...master).
-#
-#     B---E   <-- master
-#    / \ /
-#   A   X
-#    \ / \
-#     C---D--G   <-- br1
-#      \    /
-#       ---F   <-- br2
-#
-#  H  <-- br3
-#
-# We put files into a few commits so that we can verify the
-# output as well.
-
-test_expect_success setup '
-	git commit --allow-empty -m A &&
-	echo b >b &&
-	git add b &&
-	git commit -m B &&
-	git checkout -b br1 HEAD^ &&
-	echo c >c &&
-	git add c &&
-	git commit -m C &&
-	git tag commit-C &&
-	git merge -m D master &&
-	git tag commit-D &&
-	git checkout master &&
-	git merge -m E commit-C &&
-	git checkout -b br2 commit-C &&
-	echo f >f &&
-	git add f &&
-	git commit -m F &&
-	git checkout br1 &&
-	git merge -m G br2 &&
-	git checkout --orphan br3 &&
-	git commit -m H
-'
-
-test_expect_success 'diff with one merge base' '
-	git diff commit-D...br1 >tmp &&
-	tail -n 1 tmp >actual &&
-	echo +f >expect &&
-	test_cmp expect actual
-'
-
-# The output (in tmp) can have +b or +c depending
-# on which merge base (commit B or C) is picked.
-# It should have one of those two, which comes out
-# to seven lines.
-test_expect_success 'diff with two merge bases' '
-	git diff br1...master >tmp 2>err &&
-	test_line_count = 7 tmp &&
-	test_line_count = 1 err
-'
-
-test_expect_success 'diff with no merge bases' '
-	test_must_fail git diff br2...br3 >tmp 2>err &&
-	test_i18ngrep "fatal: br2...br3: no merge base" err
-'
-
-test_expect_success 'diff with too many symmetric differences' '
-	test_must_fail git diff br1...master br2...br3 >tmp 2>err &&
-	test_i18ngrep "usage" err
-'
-
-test_expect_success 'diff with symmetric difference and extraneous arg' '
-	test_must_fail git diff master br1...master >tmp 2>err &&
-	test_i18ngrep "usage" err
-'
-
-test_expect_success 'diff with two ranges' '
-	test_must_fail git diff master br1..master br2..br3 >tmp 2>err &&
-	test_i18ngrep "usage" err
-'
-
-test_expect_success 'diff with ranges and extra arg' '
-	test_must_fail git diff master br1..master commit-D >tmp 2>err &&
-	test_i18ngrep "usage" err
-'
-
-test_done