[PATCH 0/4] Cleanup of merge_*() functions in merge-recursive

[PATCH 0/4] Cleanup of merge_*() functions in merge-recursive

[Elijah Newren]

While working on a series to make file collision conflict handling
consistent, I discovered a latent bug in merge_content()...and several
opportunities for cleanup.  This series fixes that bug, deletes the
merge_file_special_markers() and merge_file_one() functions, and
renames a pair of functions to make them have a better description.

Elijah Newren (4):
  merge-recursive: set paths correctly when three-way merging content
  merge-recursive: avoid wrapper function when unnecessary and wasteful
  merge-recursive: remove final remaining caller of merge_file_one()
  merge-recursive: rename merge_file_1() and merge_content()

 merge-recursive.c | 144 ++++++++++++++++------------------------------
 1 file changed, 51 insertions(+), 93 deletions(-)

-- 
2.19.0.12.gc6760fd9a9

[PATCH 1/4] merge-recursive: set paths correctly when three-way merging content

[Elijah Newren]

merge_3way() has code to mark different sides of the conflict with info
about where the content comes from.  If the names of the files involved
match, it simply uses the branch name.  If the names of the files do not
match, it uses branchname:filename.  Unfortunately, merge_content()
previously always called it with one.path = a.path = b.path.  Granted,
it didn't have other path information available to it for years, but
that was corrected by passing rename_conflict_info in commit
3c217c077a86 ("merge-recursive: Provide more info in conflict markers
with file renames", 2011-08-11).  In that commit, instead of just fixing
the bug with the pathnames, it created fake branch names incorporating
both the branch name and file name.

This "fake branch" workaround was extended further when I pulled that
logic out into a special function in commit dac4741554e7
("merge-recursive: Create function for merging with branchname:file
markers", 2011-08-11), and a number of other sites outside of
merge_content() have been added which call into that.  However, this
Rube-Goldberg-esque setup is not merely duplicate code and unnecessary
work, it also risked having other callsites invoke it in a way that
would result in markers of the form branchname:filename:filename (i.e.
with the filename repeated).

Fix this whole mess by:
  - setting one.path, a.path, and b.path appropriately
  - calling merge_file_1() directly
  - deleting the merge_file_special_markers() workaround wrapper

Signed-off-by: Elijah Newren <newren@gmail.com>
---
 merge-recursive.c | 49 +++++++++--------------------------------------
 1 file changed, 9 insertions(+), 40 deletions(-)

diff --git a/merge-recursive.c b/merge-recursive.c
index 45a163c555..99a7ac5ec7 100644
--- a/merge-recursive.c
+++ b/merge-recursive.c
@@ -1366,35 +1366,6 @@ static int merge_file_1(struct merge_options *o,
 	return 0;
 }
 
-static int merge_file_special_markers(struct merge_options *o,
-				      const struct diff_filespec *one,
-				      const struct diff_filespec *a,
-				      const struct diff_filespec *b,
-				      const char *target_filename,
-				      const char *branch1,
-				      const char *filename1,
-				      const char *branch2,
-				      const char *filename2,
-				      struct merge_file_info *mfi)
-{
-	char *side1 = NULL;
-	char *side2 = NULL;
-	int ret;
-
-	if (filename1)
-		side1 = xstrfmt("%s:%s", branch1, filename1);
-	if (filename2)
-		side2 = xstrfmt("%s:%s", branch2, filename2);
-
-	ret = merge_file_1(o, one, a, b, target_filename,
-			   side1 ? side1 : branch1,
-			   side2 ? side2 : branch2, mfi);
-
-	free(side1);
-	free(side2);
-	return ret;
-}
-
 static int merge_file_one(struct merge_options *o,
 			  const char *path,
 			  const struct object_id *o_oid, int o_mode,
@@ -1729,14 +1700,10 @@ static int handle_rename_rename_2to1(struct merge_options *o,
 
 	path_side_1_desc = xstrfmt("%s (was %s)", path, a->path);
 	path_side_2_desc = xstrfmt("%s (was %s)", path, b->path);
-	if (merge_file_special_markers(o, a, c1, &ci->ren1_other,
-				       path_side_1_desc,
-				       o->branch1, c1->path,
-				       o->branch2, ci->ren1_other.path, &mfi_c1) ||
-	    merge_file_special_markers(o, b, &ci->ren2_other, c2,
-				       path_side_2_desc,
-				       o->branch1, ci->ren2_other.path,
-				       o->branch2, c2->path, &mfi_c2))
+	if (merge_file_1(o, a, c1, &ci->ren1_other, path_side_1_desc,
+			 o->branch1, o->branch2, &mfi_c1) ||
+	    merge_file_1(o, b, &ci->ren2_other, c2, path_side_2_desc,
+			 o->branch1, o->branch2, &mfi_c2))
 		return -1;
 	free(path_side_1_desc);
 	free(path_side_2_desc);
@@ -3059,14 +3026,16 @@ static int merge_content(struct merge_options *o,
 		path2 = (rename_conflict_info->pair2 ||
 			 o->branch2 == rename_conflict_info->branch1) ?
 			pair1->two->path : pair1->one->path;
+		one.path = pair1->one->path;
+		a.path = (char *)path1;
+		b.path = (char *)path2;
 
 		if (dir_in_way(path, !o->call_depth,
 			       S_ISGITLINK(pair1->two->mode)))
 			df_conflict_remains = 1;
 	}
-	if (merge_file_special_markers(o, &one, &a, &b, path,
-				       o->branch1, path1,
-				       o->branch2, path2, &mfi))
+	if (merge_file_1(o, &one, &a, &b, path,
+			 o->branch1, o->branch2, &mfi))
 		return -1;
 
 	/*
-- 
2.19.0.12.gc6760fd9a9

[PATCH 2/4] merge-recursive: avoid wrapper function when unnecessary and wasteful

[Elijah Newren]

merge_file_one() is a convenience function taking a bunch of oids and
modes, combining each pair into a diff_filespec, and then calling
merge_file_1().  When we already start with diff_filespec's, we can
just call merge_file_1() directly instead of splitting out the oids
and modes for the wrapper to recombine into what we already had.

Signed-off-by: Elijah Newren <newren@gmail.com>
---
 merge-recursive.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/merge-recursive.c b/merge-recursive.c
index 99a7ac5ec7..9e4e3da672 100644
--- a/merge-recursive.c
+++ b/merge-recursive.c
@@ -1630,10 +1630,7 @@ static int handle_rename_rename_1to2(struct merge_options *o,
 		struct merge_file_info mfi;
 		struct diff_filespec other;
 		struct diff_filespec *add;
-		if (merge_file_one(o, one->path,
-				 &one->oid, one->mode,
-				 &a->oid, a->mode,
-				 &b->oid, b->mode,
+		if (merge_file_1(o, one, a, b, one->path,
 				 ci->branch1, ci->branch2, &mfi))
 			return -1;
 
-- 
2.19.0.12.gc6760fd9a9

[PATCH 3/4] merge-recursive: remove final remaining caller of merge_file_one()

[Elijah Newren]

The function names merge_file_one() and merge_file_1() aren't
particularly intuitive function names, especially since there is no
associated merge_file() function that these are related to.  The
previous commit showed that merge_file_one() was prone to be called when
merge_file_1() should be, and since it is just a thin wrapper around
merge_file_1() anyway and only has one caller left, let's just remove
merge_file_one() entirely.

(It also turns out that the one remaining caller of merge_file_one()
has very broken code that needs to be completely rewritten, but that's
the subject of a future patch series; for now, we're just translating
it into a merge_file_1() call.)

Signed-off-by: Elijah Newren <newren@gmail.com>
---
 merge-recursive.c | 44 +++++++++++++++++---------------------------
 1 file changed, 17 insertions(+), 27 deletions(-)

diff --git a/merge-recursive.c b/merge-recursive.c
index 9e4e3da672..2654a8a485 100644
--- a/merge-recursive.c
+++ b/merge-recursive.c
@@ -1366,27 +1366,6 @@ static int merge_file_1(struct merge_options *o,
 	return 0;
 }
 
-static int merge_file_one(struct merge_options *o,
-			  const char *path,
-			  const struct object_id *o_oid, int o_mode,
-			  const struct object_id *a_oid, int a_mode,
-			  const struct object_id *b_oid, int b_mode,
-			  const char *branch1,
-			  const char *branch2,
-			  struct merge_file_info *mfi)
-{
-	struct diff_filespec one, a, b;
-
-	one.path = a.path = b.path = (char *)path;
-	oidcpy(&one.oid, o_oid);
-	one.mode = o_mode;
-	oidcpy(&a.oid, a_oid);
-	a.mode = a_mode;
-	oidcpy(&b.oid, b_oid);
-	b.mode = b_mode;
-	return merge_file_1(o, &one, &a, &b, path, branch1, branch2, mfi);
-}
-
 static int handle_rename_via_dir(struct merge_options *o,
 				 struct diff_filepair *pair,
 				 const char *rename_branch,
@@ -2730,12 +2709,23 @@ static int process_renames(struct merge_options *o,
 				       ren1_dst, branch2);
 				if (o->call_depth) {
 					struct merge_file_info mfi;
-					if (merge_file_one(o, ren1_dst, &null_oid, 0,
-							   &ren1->pair->two->oid,
-							   ren1->pair->two->mode,
-							   &dst_other.oid,
-							   dst_other.mode,
-							   branch1, branch2, &mfi)) {
+					struct diff_filespec one, a, b;
+
+					oidcpy(&one.oid, &null_oid);
+					one.mode = 0;
+					one.path = ren1->pair->two->path;
+
+					oidcpy(&a.oid, &ren1->pair->two->oid);
+					a.mode = ren1->pair->two->mode;
+					a.path = one.path;
+
+					oidcpy(&b.oid, &dst_other.oid);
+					b.mode = dst_other.mode;
+					b.path = one.path;
+
+					if (merge_file_1(o, &one, &a, &b, ren1_dst,
+							 branch1, branch2,
+							 &mfi)) {
 						clean_merge = -1;
 						goto cleanup_and_return;
 					}
-- 
2.19.0.12.gc6760fd9a9

[PATCH 4/4] merge-recursive: rename merge_file_1() and merge_content()

[Elijah Newren]

Summary:
  merge_file_1()  -> merge_mode_and_contents()
  merge_content() -> handle_content_merge()

merge_file_1() is a very unhelpful name.  Rename it to
merge_mode_and_contents() to reflect what it does.

merge_content() calls merge_mode_and_contents() to do the main part of
its work, but most of this function was about higher level stuff, e.g.
printing out conflict messages, updating skip_worktree bits, checking
for ability to avoid updating the working tree or for D/F conflicts
being in the way, etc.  Since there are several handle_*() functions for
similar levels of checking and handling in merge-recursive.c (e.g.
handle_change_delete(), handle_rename_rename_2to1()), let's rename this
function to handle_content_merge().

Signed-off-by: Elijah Newren <newren@gmail.com>
---
 merge-recursive.c | 66 ++++++++++++++++++++++++-----------------------
 1 file changed, 34 insertions(+), 32 deletions(-)

diff --git a/merge-recursive.c b/merge-recursive.c
index 2654a8a485..5206d6cfb6 100644
--- a/merge-recursive.c
+++ b/merge-recursive.c
@@ -1274,14 +1274,14 @@ static int merge_submodule(struct merge_options *o,
 	return 0;
 }
 
-static int merge_file_1(struct merge_options *o,
-			const struct diff_filespec *one,
-			const struct diff_filespec *a,
-			const struct diff_filespec *b,
-			const char *filename,
-			const char *branch1,
-			const char *branch2,
-			struct merge_file_info *result)
+static int merge_mode_and_contents(struct merge_options *o,
+				   const struct diff_filespec *one,
+				   const struct diff_filespec *a,
+				   const struct diff_filespec *b,
+				   const char *filename,
+				   const char *branch1,
+				   const char *branch2,
+				   struct merge_file_info *result)
 {
 	result->merge = 0;
 	result->clean = 1;
@@ -1609,8 +1609,8 @@ static int handle_rename_rename_1to2(struct merge_options *o,
 		struct merge_file_info mfi;
 		struct diff_filespec other;
 		struct diff_filespec *add;
-		if (merge_file_1(o, one, a, b, one->path,
-				 ci->branch1, ci->branch2, &mfi))
+		if (merge_mode_and_contents(o, one, a, b, one->path,
+					    ci->branch1, ci->branch2, &mfi))
 			return -1;
 
 		/*
@@ -1676,10 +1676,10 @@ static int handle_rename_rename_2to1(struct merge_options *o,
 
 	path_side_1_desc = xstrfmt("%s (was %s)", path, a->path);
 	path_side_2_desc = xstrfmt("%s (was %s)", path, b->path);
-	if (merge_file_1(o, a, c1, &ci->ren1_other, path_side_1_desc,
-			 o->branch1, o->branch2, &mfi_c1) ||
-	    merge_file_1(o, b, &ci->ren2_other, c2, path_side_2_desc,
-			 o->branch1, o->branch2, &mfi_c2))
+	if (merge_mode_and_contents(o, a, c1, &ci->ren1_other, path_side_1_desc,
+				    o->branch1, o->branch2, &mfi_c1) ||
+	    merge_mode_and_contents(o, b, &ci->ren2_other, c2, path_side_2_desc,
+				    o->branch1, o->branch2, &mfi_c2))
 		return -1;
 	free(path_side_1_desc);
 	free(path_side_2_desc);
@@ -2723,9 +2723,9 @@ static int process_renames(struct merge_options *o,
 					b.mode = dst_other.mode;
 					b.path = one.path;
 
-					if (merge_file_1(o, &one, &a, &b, ren1_dst,
-							 branch1, branch2,
-							 &mfi)) {
+					if (merge_mode_and_contents(o, &one, &a, &b, ren1_dst,
+								    branch1, branch2,
+								    &mfi)) {
 						clean_merge = -1;
 						goto cleanup_and_return;
 					}
@@ -2975,13 +2975,13 @@ static int handle_modify_delete(struct merge_options *o,
 				    _("modify"), _("modified"));
 }
 
-static int merge_content(struct merge_options *o,
-			 const char *path,
-			 int is_dirty,
-			 struct object_id *o_oid, int o_mode,
-			 struct object_id *a_oid, int a_mode,
-			 struct object_id *b_oid, int b_mode,
-			 struct rename_conflict_info *rename_conflict_info)
+static int handle_content_merge(struct merge_options *o,
+				const char *path,
+				int is_dirty,
+				struct object_id *o_oid, int o_mode,
+				struct object_id *a_oid, int a_mode,
+				struct object_id *b_oid, int b_mode,
+				struct rename_conflict_info *rename_conflict_info)
 {
 	const char *reason = _("content");
 	const char *path1 = NULL, *path2 = NULL;
@@ -3021,8 +3021,8 @@ static int merge_content(struct merge_options *o,
 			       S_ISGITLINK(pair1->two->mode)))
 			df_conflict_remains = 1;
 	}
-	if (merge_file_1(o, &one, &a, &b, path,
-			 o->branch1, o->branch2, &mfi))
+	if (merge_mode_and_contents(o, &one, &a, &b, path,
+				    o->branch1, o->branch2, &mfi))
 		return -1;
 
 	/*
@@ -3113,9 +3113,9 @@ static int handle_rename_normal(struct merge_options *o,
 				struct rename_conflict_info *ci)
 {
 	/* Merge the content and write it out */
-	return merge_content(o, path, was_dirty(o, path),
-			     o_oid, o_mode, a_oid, a_mode, b_oid, b_mode,
-			     ci);
+	return handle_content_merge(o, path, was_dirty(o, path),
+				    o_oid, o_mode, a_oid, a_mode, b_oid, b_mode,
+				    ci);
 }
 
 /* Per entry merge function */
@@ -3239,9 +3239,11 @@ static int process_entry(struct merge_options *o,
 		/* Case C: Added in both (check for same permissions) and */
 		/* case D: Modified in both, but differently. */
 		int is_dirty = 0; /* unpack_trees would have bailed if dirty */
-		clean_merge = merge_content(o, path, is_dirty,
-					    o_oid, o_mode, a_oid, a_mode, b_oid, b_mode,
-					    NULL);
+		clean_merge = handle_content_merge(o, path, is_dirty,
+						   o_oid, o_mode,
+						   a_oid, a_mode,
+						   b_oid, b_mode,
+						   NULL);
 	} else if (!o_oid && !a_oid && !b_oid) {
 		/*
 		 * this entry was deleted altogether. a_mode == 0 means
-- 
2.19.0.12.gc6760fd9a9

Re: [PATCH 4/4] merge-recursive: rename merge_file_1() and merge_content()

[Stefan Beller]

On Wed, Sep 19, 2018 at 9:15 AM Elijah Newren <newren@gmail.com> wrote:
>
> Summary:
>   merge_file_1()  -> merge_mode_and_contents()
>   merge_content() -> handle_content_merge()
>
> merge_file_1() is a very unhelpful name.  Rename it to
> merge_mode_and_contents() to reflect what it does.
>
> merge_content() calls merge_mode_and_contents() to do the main part of
> its work, but most of this function was about higher level stuff, e.g.
> printing out conflict messages, updating skip_worktree bits, checking
> for ability to avoid updating the working tree or for D/F conflicts
> being in the way, etc.  Since there are several handle_*() functions for
> similar levels of checking and handling in merge-recursive.c (e.g.
> handle_change_delete(), handle_rename_rename_2to1()), let's rename this
> function to handle_content_merge().
>
> Signed-off-by: Elijah Newren <newren@gmail.com>

I looked through the whole series and 1,2,4 are obvious improvements IMHO,
and 3 in itself is not worth it if it weren't for 4 (as now we don't
have neither
_1 and _one functions in this file).

The whole series looks good to me.

Thanks,
Stefan