Merge branch 'by/log-follow'

* by/log-follow:
  tests: rename duplicate t4205
  Make git log --follow find copies among unmodified files.
  Make diffcore_std only can run once before a diff_flush
  Add a macro DIFF_QUEUE_CLEAR.

8 files changed, 82 insertions, 18 deletions

diff --git a/Documentation/git-log.txt b/Documentation/git-log.txt
index 57aa57467..a2d55f974 100644
--- a/Documentation/git-log.txt
+++ b/Documentation/git-log.txt
@@ -57,7 +57,7 @@ include::diff-options.txt[]
 	commits, and doesn't limit diff for those commits.
 
 --follow::
-	Continue listing the history of a file beyond renames.
+	Continue listing the history of a file beyond renames/copies.
 
 --log-size::
 	Before the log message print out its size in bytes. Intended
diff --git a/diff.c b/diff.c
index 502b30167..494f5601e 100644
--- a/diff.c
+++ b/diff.c
@@ -2600,6 +2600,7 @@ static void run_checkdiff(struct diff_filepair *p, struct diff_options *o)
 void diff_setup(struct diff_options *options)
 {
 	memset(options, 0, sizeof(*options));
+	memset(&diff_queued_diff, 0, sizeof(diff_queued_diff));
 
 	options->file = stdout;
 
@@ -3541,8 +3542,7 @@ int diff_flush_patch_id(struct diff_options *options, unsigned char *sha1)
 		diff_free_filepair(q->queue[i]);
 
 	free(q->queue);
-	q->queue = NULL;
-	q->nr = q->alloc = 0;
+	DIFF_QUEUE_CLEAR(q);
 
 	return result;
 }
@@ -3670,8 +3670,7 @@ void diff_flush(struct diff_options *options)
 		diff_free_filepair(q->queue[i]);
 free_queue:
 	free(q->queue);
-	q->queue = NULL;
-	q->nr = q->alloc = 0;
+	DIFF_QUEUE_CLEAR(q);
 	if (options->close_file)
 		fclose(options->file);
 
@@ -3693,8 +3692,7 @@ static void diffcore_apply_filter(const char *filter)
 	int i;
 	struct diff_queue_struct *q = &diff_queued_diff;
 	struct diff_queue_struct outq;
-	outq.queue = NULL;
-	outq.nr = outq.alloc = 0;
+	DIFF_QUEUE_CLEAR(&outq);
 
 	if (!filter)
 		return;
@@ -3762,8 +3760,7 @@ static void diffcore_skip_stat_unmatch(struct diff_options *diffopt)
 	int i;
 	struct diff_queue_struct *q = &diff_queued_diff;
 	struct diff_queue_struct outq;
-	outq.queue = NULL;
-	outq.nr = outq.alloc = 0;
+	DIFF_QUEUE_CLEAR(&outq);
 
 	for (i = 0; i < q->nr; i++) {
 		struct diff_filepair *p = q->queue[i];
@@ -3824,6 +3821,12 @@ void diffcore_fix_diff_index(struct diff_options *options)
 
 void diffcore_std(struct diff_options *options)
 {
+	/* We never run this function more than one time, because the
+	 * rename/copy detection logic can only run once.
+	 */
+	if (diff_queued_diff.run)
+		return;
+
 	if (options->skip_stat_unmatch)
 		diffcore_skip_stat_unmatch(options);
 	if (options->break_opt != -1)
@@ -3843,6 +3846,8 @@ void diffcore_std(struct diff_options *options)
 		DIFF_OPT_SET(options, HAS_CHANGES);
 	else
 		DIFF_OPT_CLR(options, HAS_CHANGES);
+
+	diff_queued_diff.run = 1;
 }
 
 int diff_result_code(struct diff_options *opt, int status)
diff --git a/diffcore-break.c b/diffcore-break.c
index 3a7b60a03..44f8678d2 100644
--- a/diffcore-break.c
+++ b/diffcore-break.c
@@ -162,8 +162,7 @@ void diffcore_break(int break_score)
 	if (!merge_score)
 		merge_score = DEFAULT_MERGE_SCORE;
 
-	outq.nr = outq.alloc = 0;
-	outq.queue = NULL;
+	DIFF_QUEUE_CLEAR(&outq);
 
 	for (i = 0; i < q->nr; i++) {
 		struct diff_filepair *p = q->queue[i];
@@ -256,8 +255,7 @@ void diffcore_merge_broken(void)
 	struct diff_queue_struct outq;
 	int i, j;
 
-	outq.nr = outq.alloc = 0;
-	outq.queue = NULL;
+	DIFF_QUEUE_CLEAR(&outq);
 
 	for (i = 0; i < q->nr; i++) {
 		struct diff_filepair *p = q->queue[i];
diff --git a/diffcore-pickaxe.c b/diffcore-pickaxe.c
index d0ef83970..929de15aa 100644
--- a/diffcore-pickaxe.c
+++ b/diffcore-pickaxe.c
@@ -55,8 +55,7 @@ void diffcore_pickaxe(const char *needle, int opts)
 	int i, has_changes;
 	regex_t regex, *regexp = NULL;
 	struct diff_queue_struct outq;
-	outq.queue = NULL;
-	outq.nr = outq.alloc = 0;
+	DIFF_QUEUE_CLEAR(&outq);
 
 	if (opts & DIFF_PICKAXE_REGEX) {
 		int err;
diff --git a/diffcore-rename.c b/diffcore-rename.c
index d6fd3cacd..df41be56d 100644
--- a/diffcore-rename.c
+++ b/diffcore-rename.c
@@ -569,8 +569,7 @@ void diffcore_rename(struct diff_options *options)
 	/* At this point, we have found some renames and copies and they
 	 * are recorded in rename_dst.  The original list is still in *q.
 	 */
-	outq.queue = NULL;
-	outq.nr = outq.alloc = 0;
+	DIFF_QUEUE_CLEAR(&outq);
 	for (i = 0; i < q->nr; i++) {
 		struct diff_filepair *p = q->queue[i];
 		struct diff_filepair *pair_to_free = NULL;
diff --git a/diffcore.h b/diffcore.h
index fcd00bf27..491bea0b4 100644
--- a/diffcore.h
+++ b/diffcore.h
@@ -91,7 +91,14 @@ struct diff_queue_struct {
 	struct diff_filepair **queue;
 	int alloc;
 	int nr;
+	int run;
 };
+#define DIFF_QUEUE_CLEAR(q) \
+	do { \
+		(q)->queue = NULL; \
+		(q)->nr = (q)->alloc = 0; \
+		(q)->run = 0; \
+	} while(0);
 
 extern struct diff_queue_struct diff_queued_diff;
 extern struct diff_filepair *diff_queue(struct diff_queue_struct *,
diff --git a/t/t4206-log-follow-harder-copies.sh b/t/t4206-log-follow-harder-copies.sh
new file mode 100755
index 000000000..ad29e65fc
--- /dev/null
+++ b/t/t4206-log-follow-harder-copies.sh
@@ -0,0 +1,56 @@
+#!/bin/sh
+#
+# Copyright (c) 2010 Bo Yang
+#
+
+test_description='Test --follow should always find copies hard in git log.
+
+'
+. ./test-lib.sh
+. "$TEST_DIRECTORY"/diff-lib.sh
+
+echo >path0 'Line 1
+Line 2
+Line 3
+'
+
+test_expect_success \
+    'add a file path0 and commit.' \
+    'git add path0 &&
+     git commit -m "Add path0"'
+
+echo >path0 'New line 1
+New line 2
+New line 3
+'
+test_expect_success \
+    'Change path0.' \
+    'git add path0 &&
+     git commit -m "Change path0"'
+
+cat <path0 >path1
+test_expect_success \
+    'copy path0 to path1.' \
+    'git add path1 &&
+     git commit -m "Copy path1 from path0"'
+
+test_expect_success \
+    'find the copy path0 -> path1 harder' \
+    'git log --follow --name-status --pretty="format:%s"  path1 > current'
+
+cat >expected <<\EOF
+Copy path1 from path0
+C100	path0	path1
+
+Change path0
+M	path0
+
+Add path0
+A	path0
+EOF
+
+test_expect_success \
+    'validate the output.' \
+    'compare_diff_patch current expected'
+
+test_done
diff --git a/tree-diff.c b/tree-diff.c
index fe9f52c47..1fb3e9461 100644
--- a/tree-diff.c
+++ b/tree-diff.c
@@ -346,7 +346,7 @@ static void try_to_follow_renames(struct tree_desc *t1, struct tree_desc *t2, co
 
 	diff_setup(&diff_opts);
 	DIFF_OPT_SET(&diff_opts, RECURSIVE);
-	diff_opts.detect_rename = DIFF_DETECT_RENAME;
+	DIFF_OPT_SET(&diff_opts, FIND_COPIES_HARDER);
 	diff_opts.output_format = DIFF_FORMAT_NO_OUTPUT;
 	diff_opts.single_follow = opt->paths[0];
 	diff_opts.break_opt = opt->break_opt;