[PATCH v2 5/5] diff: activate diff.renames by default

[Matthieu Moy <Matthieu.Moy@imag.fr>]

Rename detection is a very convenient feature, and new users shouldn't
have to dig in the documentation to benefit from it.

Potential objections to activating rename detection are that it
sometimes fail, and it is sometimes slow. But rename detection is
already activated by default in several cases like "git status" and "git
merge", so activating diff.renames does not fundamentally change the
situation. When the rename detection fails, it now fails consistently
between "git diff" and "git status".

This setting does not affect plumbing commands, hence well-written
scripts will not be affected.

Signed-off-by: Matthieu Moy <Matthieu.Moy@imag.fr>
---
 Documentation/diff-config.txt | 2 +-
 builtin/commit.c              | 1 +
 builtin/diff.c                | 1 +
 builtin/log.c                 | 1 +
 builtin/merge.c               | 1 +
 diff.c                        | 5 +++++
 diff.h                        | 1 +
 t/t4001-diff-rename.sh        | 2 +-
 t/t4013-diff-various.sh       | 2 ++
 t/t4014-format-patch.sh       | 4 ++--
 t/t4047-diff-dirstat.sh       | 3 ++-
 t/t4202-log.sh                | 8 ++++----
 12 files changed, 22 insertions(+), 9 deletions(-)

diff --git a/Documentation/diff-config.txt b/Documentation/diff-config.txt
index 40e5de9..69389ae 100644
--- a/Documentation/diff-config.txt
+++ b/Documentation/diff-config.txt
@@ -111,7 +111,7 @@ diff.renames::
 	Whether and how Git detects renames.  If set to "false",
 	rename detection is disabled. If set to "true", basic rename
 	detection is enable.  If set to "copies" or "copy", Git will
-	detect copies, as well.  Defaults to false.  Note that this
+	detect copies, as well.  Defaults to true.  Note that this
 	affects only 'git diff' Porcelain like linkgit:git-diff[1] and
 	linkgit:git-log[1], and not lower level commands such as
 	linkgit:git-diff-files[1].
diff --git a/builtin/commit.c b/builtin/commit.c
index b3bd2d4..109742e 100644
--- a/builtin/commit.c
+++ b/builtin/commit.c
@@ -186,6 +186,7 @@ static void status_init_config(struct wt_status *s, config_fn_t fn)
 	gitmodules_config();
 	git_config(fn, s);
 	determine_whence(s);
+	init_diff_ui_defaults();
 	s->hints = advice_status_hints; /* must come after git_config() */
 }
 
diff --git a/builtin/diff.c b/builtin/diff.c
index 52c98a9..343c6b8 100644
--- a/builtin/diff.c
+++ b/builtin/diff.c
@@ -318,6 +318,7 @@ int cmd_diff(int argc, const char **argv, const char *prefix)
 
 	if (!no_index)
 		gitmodules_config();
+	init_diff_ui_defaults();
 	git_config(git_diff_ui_config, NULL);
 
 	init_revisions(&rev, prefix);
diff --git a/builtin/log.c b/builtin/log.c
index 7f96c64..c05a5f6 100644
--- a/builtin/log.c
+++ b/builtin/log.c
@@ -103,6 +103,7 @@ static int log_line_range_callback(const struct option *option, const char *arg,
 static void init_log_defaults()
 {
 	init_grep_defaults();
+	init_diff_ui_defaults();
 }
 
 static void cmd_log_init_defaults(struct rev_info *rev)
diff --git a/builtin/merge.c b/builtin/merge.c
index b98a348..4cb4f6a 100644
--- a/builtin/merge.c
+++ b/builtin/merge.c
@@ -1187,6 +1187,7 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 	else
 		head_commit = lookup_commit_or_die(head_sha1, "HEAD");
 
+	init_diff_ui_defaults();
 	git_config(git_merge_config, NULL);
 
 	if (branch_mergeoptions)
diff --git a/diff.c b/diff.c
index 2136b69..b4dea07 100644
--- a/diff.c
+++ b/diff.c
@@ -168,6 +168,11 @@ long parse_algorithm_value(const char *value)
  * never be affected by the setting of diff.renames
  * the user happens to have in the configuration file.
  */
+void init_diff_ui_defaults(void)
+{
+	diff_detect_rename_default = 1;
+}
+
 int git_diff_ui_config(const char *var, const char *value, void *cb)
 {
 	if (!strcmp(var, "diff.color") || !strcmp(var, "color.diff")) {
diff --git a/diff.h b/diff.h
index 70b2d70..0a3ce86 100644
--- a/diff.h
+++ b/diff.h
@@ -266,6 +266,7 @@ extern int parse_long_opt(const char *opt, const char **argv,
 			 const char **optarg);
 
 extern int git_diff_basic_config(const char *var, const char *value, void *cb);
+extern void init_diff_ui_defaults(void);
 extern int git_diff_ui_config(const char *var, const char *value, void *cb);
 extern void diff_setup(struct diff_options *);
 extern int diff_opt_parse(struct diff_options *, const char **, int, const char *);
diff --git a/t/t4001-diff-rename.sh b/t/t4001-diff-rename.sh
index f5239b5..c7e58b6 100755
--- a/t/t4001-diff-rename.sh
+++ b/t/t4001-diff-rename.sh
@@ -124,7 +124,7 @@ test_expect_success 'test diff.renames=false' '
 
 test_expect_success 'test diff.renames unset' '
 	git diff --cached $tree >current &&
-	compare_diff_patch current no-rename
+	compare_diff_patch current expected
 '
 
 test_expect_success 'favour same basenames over different ones' '
diff --git a/t/t4013-diff-various.sh b/t/t4013-diff-various.sh
index 6ec6072..94ef500 100755
--- a/t/t4013-diff-various.sh
+++ b/t/t4013-diff-various.sh
@@ -90,6 +90,8 @@ test_expect_success setup '
 	git commit -m "Rearranged lines in dir/sub" &&
 	git checkout master &&
 
+	git config diff.renames false &&
+
 	git show-branch
 '
 
diff --git a/t/t4014-format-patch.sh b/t/t4014-format-patch.sh
index 3b99434..eed2981 100755
--- a/t/t4014-format-patch.sh
+++ b/t/t4014-format-patch.sh
@@ -549,7 +549,7 @@ test_expect_success 'cover-letter inherits diff options' '
 
 	git mv file foo &&
 	git commit -m foo &&
-	git format-patch --cover-letter -1 &&
+	git format-patch --no-renames --cover-letter -1 &&
 	check_patch 0000-cover-letter.patch &&
 	! grep "file => foo .* 0 *\$" 0000-cover-letter.patch &&
 	git format-patch --cover-letter -1 -M &&
@@ -703,7 +703,7 @@ test_expect_success 'options no longer allowed for format-patch' '
 
 test_expect_success 'format-patch --numstat should produce a patch' '
 	git format-patch --numstat --stdout master..side > output &&
-	test 6 = $(grep "^diff --git a/" output | wc -l)'
+	test 5 = $(grep "^diff --git a/" output | wc -l)'
 
 test_expect_success 'format-patch -- <path>' '
 	git format-patch master..side -- file 2>error &&
diff --git a/t/t4047-diff-dirstat.sh b/t/t4047-diff-dirstat.sh
index 3b8b792..447a8ff 100755
--- a/t/t4047-diff-dirstat.sh
+++ b/t/t4047-diff-dirstat.sh
@@ -248,7 +248,8 @@ EOF
 	git rm -r src/move/unchanged &&
 	git rm -r src/move/changed &&
 	git rm -r src/move/rearranged &&
-	git commit -m "changes"
+	git commit -m "changes" &&
+	git config diff.renames false
 '
 
 cat <<EOF >expect_diff_stat
diff --git a/t/t4202-log.sh b/t/t4202-log.sh
index cb82eb7..128ba93 100755
--- a/t/t4202-log.sh
+++ b/t/t4202-log.sh
@@ -101,8 +101,8 @@ test_expect_success 'oneline' '
 
 test_expect_success 'diff-filter=A' '
 
-	git log --pretty="format:%s" --diff-filter=A HEAD > actual &&
-	git log --pretty="format:%s" --diff-filter A HEAD > actual-separate &&
+	git log --no-renames --pretty="format:%s" --diff-filter=A HEAD > actual &&
+	git log --no-renames --pretty="format:%s" --diff-filter A HEAD > actual-separate &&
 	printf "fifth\nfourth\nthird\ninitial" > expect &&
 	test_cmp expect actual &&
 	test_cmp expect actual-separate
@@ -119,7 +119,7 @@ test_expect_success 'diff-filter=M' '
 
 test_expect_success 'diff-filter=D' '
 
-	actual=$(git log --pretty="format:%s" --diff-filter=D HEAD) &&
+	actual=$(git log --no-renames --pretty="format:%s" --diff-filter=D HEAD) &&
 	expect=$(echo sixth ; echo third) &&
 	verbose test "$actual" = "$expect"
 
@@ -848,7 +848,7 @@ sanitize_output () {
 }
 
 test_expect_success 'log --graph with diff and stats' '
-	git log --graph --pretty=short --stat -p >actual &&
+	git log --no-renames --graph --pretty=short --stat -p >actual &&
 	sanitize_output >actual.sanitized <actual &&
 	test_i18ncmp expect actual.sanitized
 '
-- 
2.7.2.334.g35ed2ae.dirty