Introduce git_blame_options diff find configurability

This introduces a git_diff_find_options structure into
git_blame_options that can be used to filter out what
kind of file diffing to take place.

Added a new entry GIT_DIFF_FIND_NO_RENAMES which discards
any attempt of the library to check for renames.

The blobs added have the following steps:

Commit 'H': 49aed320fb734fe132f8a0723743b78ab369b17c
Added c.txt and d.txt, files with 2 blocks of text.

Commit 'I': c347c9265f655dcd26dd0d41a244d4c1bb6cb8c6
Renamed c.txt to c_exact.txt.

Commit 'J': c66b79ec0ee8f5aa0e981168c4c96e5e2483d361
Renamed d.txt to d_similar.txt and modified a block of text.

(cherry picked from commit 933a7b17c9)

CHANGELOG.md

@@ -720,6 +720,12 @@ v0.23
 * `git_submodule_set_branch()` allows to set the configured branch for
   a submodule.
 
+* `git_blame_options` has been taught how to handle diff find options
+  through its find_options field.
+
+* `git_diff_find_t` has now been taught how to ignore rename handling
+  completely through `GIT_DIFF_FIND_NO_RENAMES`.
+
 ### API removals
 
 * `git_remote_save()` and `git_remote_clear_refspecs()` have been

include/git2/blame.h

@@ -9,6 +9,7 @@
 #define INCLUDE_git_blame_h__
 
 #include "common.h"
+#include "diff.h"
 #include "oid.h"
 
 /**
@@ -52,6 +53,9 @@ typedef enum {
  * `GIT_BLAME_OPTIONS_INIT` macro:
  *     git_blame_options opts = GIT_BLAME_OPTIONS_INIT;
  *
+ *- `find_options` specifies what strategies should be used for
+ *               rename detection. The default is rename with threshold
+ *               heuristics.
  * - `flags` is a combination of the `git_blame_flag_t` values above.
  * - `min_match_characters` is the lower bound on the number of alphanumeric
  *   characters that must be detected as moving/copying within a file for it to
@@ -70,6 +74,8 @@ typedef enum {
 typedef struct git_blame_options {
 	unsigned int version;
 
+	git_diff_find_options find_options;
+
 	uint32_t flags;
 	uint16_t min_match_characters;
 	git_oid newest_commit;
@@ -78,8 +84,12 @@ typedef struct git_blame_options {
 	size_t max_line;
 } git_blame_options;
 
+#define GIT_BLAME_DIFF_FIND_OPTIONS_INIT {GIT_DIFF_FIND_OPTIONS_VERSION, \
+	GIT_DIFF_FIND_RENAMES }
+
 #define GIT_BLAME_OPTIONS_VERSION 1
-#define GIT_BLAME_OPTIONS_INIT {GIT_BLAME_OPTIONS_VERSION}
+#define GIT_BLAME_OPTIONS_INIT {GIT_BLAME_OPTIONS_VERSION, \
+	GIT_BLAME_DIFF_FIND_OPTIONS_INIT }
 
 /**
  * Initializes a `git_blame_options` with default values. Equivalent to

include/git2/diff.h

@@ -627,6 +627,9 @@ typedef enum {
 	/** Turn on all finding features. */
 	GIT_DIFF_FIND_ALL = (0x0ff),
 
+	/** Does no work on trying to find renames. */
+	GIT_DIFF_FIND_NO_RENAMES = (1u << 8),
+
 	/** Measure similarity ignoring leading whitespace (default) */
 	GIT_DIFF_FIND_IGNORE_LEADING_WHITESPACE = 0,
 	/** Measure similarity ignoring all whitespace */

src/blame_git.c

@@ -440,7 +440,6 @@ static git_blame__origin* find_origin(
 		/* No changes; copy data */
 		git_blame__get_origin(&porigin, blame, parent, origin->path);
 	} else {
-		git_diff_find_options findopts = GIT_DIFF_FIND_OPTIONS_INIT;
 		int i;
 
 		/* Generate a full diff between the two trees */
@@ -449,9 +448,7 @@ static git_blame__origin* find_origin(
 		if (0 != git_diff_tree_to_tree(&difflist, blame->repository, ptree, otree, &diffopts))
 			goto cleanup;
 
-		/* Let diff find renames */
-		findopts.flags = GIT_DIFF_FIND_RENAMES;
-		if (0 != git_diff_find_similar(difflist, &findopts))
+		if (0 != git_diff_find_similar(difflist, &blame->options.find_options))
 			goto cleanup;
 
 		/* Find one that matches */

src/diff_tform.c

@@ -302,6 +302,9 @@ static int normalize_find_opts(
 	if (opts->flags & GIT_DIFF_BREAK_REWRITES)
 		opts->flags |= GIT_DIFF_FIND_REWRITES;
 
+	if (opts->flags & GIT_DIFF_FIND_NO_RENAMES)
+		opts->flags &= ~GIT_DIFF_FIND_ALL;
+
 #define USE_DEFAULT(X) ((X) == 0 || (X) > 100)
 
 	if (USE_DEFAULT(opts->rename_threshold))

tests/blame/simple.c

@@ -334,3 +334,52 @@ void test_blame_simple__can_restrict_to_first_parent_commits(void)
 	check_blame_hunk_index(g_repo, g_blame, 2,  6, 5, 0, "63d671eb", "b.txt");
 	check_blame_hunk_index(g_repo, g_blame, 3, 11, 5, 0, "bc7c5ac2", "b.txt");
 }
+
+void test_blame_simple__can_follow_renames(void)
+{
+	git_blame_options opts = GIT_BLAME_OPTIONS_INIT;
+
+	cl_git_pass(git_repository_open(&g_repo, cl_fixture("blametest.git")));
+
+	cl_git_pass(git_blame_file(&g_blame, g_repo, "c_exact.txt", &opts));
+	cl_assert_equal_i(1, git_blame_get_hunk_count(g_blame));
+	check_blame_hunk_index(g_repo, g_blame, 0,  1, 10, 0, "49aed320", "c.txt");
+
+	cl_git_pass(git_blame_file(&g_blame, g_repo, "d_similar.txt", &opts));
+	cl_assert_equal_i(3, git_blame_get_hunk_count(g_blame));
+	check_blame_hunk_index(g_repo, g_blame, 0,  1, 5, 0, "49aed320", "d.txt");
+	check_blame_hunk_index(g_repo, g_blame, 1,  6, 4, 0, "c66b79ec", "d_similar.txt");
+	check_blame_hunk_index(g_repo, g_blame, 2,  10, 1, 0, "49aed320", "d.txt");
+}
+
+void test_blame_simple__can_follow_only_exact_renames(void)
+{
+	git_blame_options opts = GIT_BLAME_OPTIONS_INIT;
+	opts.find_options.flags = GIT_DIFF_FIND_EXACT_MATCH_ONLY;
+
+	cl_git_pass(git_repository_open(&g_repo, cl_fixture("blametest.git")));
+
+	cl_git_pass(git_blame_file(&g_blame, g_repo, "c_exact.txt", &opts));
+	cl_assert_equal_i(1, git_blame_get_hunk_count(g_blame));
+	check_blame_hunk_index(g_repo, g_blame, 0,  1, 10, 0, "49aed320", "c.txt");
+
+	cl_git_pass(git_blame_file(&g_blame, g_repo, "d_similar.txt", &opts));
+	cl_assert_equal_i(1, git_blame_get_hunk_count(g_blame));
+	check_blame_hunk_index(g_repo, g_blame, 0,  1, 10, 0, "c66b79ec", "d_similar.txt");
+}
+
+void test_blame_simple__does_not_follow_renames(void)
+{
+	git_blame_options opts = GIT_BLAME_OPTIONS_INIT;
+	opts.find_options.flags = GIT_DIFF_FIND_NO_RENAMES;
+
+	cl_git_pass(git_repository_open(&g_repo, cl_fixture("blametest.git")));
+
+	cl_git_pass(git_blame_file(&g_blame, g_repo, "c_exact.txt", &opts));
+	cl_assert_equal_i(1, git_blame_get_hunk_count(g_blame));
+	check_blame_hunk_index(g_repo, g_blame, 0,  1, 10, 0, "c347c926", "c_exact.txt");
+
+	cl_git_pass(git_blame_file(&g_blame, g_repo, "d_similar.txt", &opts));
+	cl_assert_equal_i(1, git_blame_get_hunk_count(g_blame));
+	check_blame_hunk_index(g_repo, g_blame, 0,  1, 10, 0, "c66b79ec", "d_similar.txt");
+}

tests/resources/blametest.git/objects/c3/47c9265f655dcd26dd0d41a244d4c1bb6cb8c6

@@ -0,0 +1,2 @@
+x
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tests/resources/blametest.git/objects/c6/6b79ec0ee8f5aa0e981168c4c96e5e2483d361

@@ -0,0 +1,2 @@
+x
5ŹËj1E»öWh—E!ř!{f ”@v-]¶{Yö¤CâqđŘĄź_§Ź•¤sá Ë9ĄĄ‚FóPKŚŕF¬
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tests/resources/blametest.git/refs/heads/master

@@ -1 +1 @@
-6653ff42313eb5c82806f145391b18a9699800c7
+c66b79ec0ee8f5aa0e981168c4c96e5e2483d361