[PATCH v4 07/16] merge-recursive: avoid returning a wholesale struct

[Johannes Schindelin <johannes.schindelin@gmx.de>]

It is technically allowed, as per C89, for functions' return type to
be complete structs (i.e. *not* just pointers to structs).

However, it was just an oversight of this developer when converting
Python code to C code in 6d297f8 (Status update on merge-recursive in
C, 2006-07-08) which introduced such a return type.

Besides, by converting this construct to pass in the struct, we can now
start returning a value that can indicate errors in future patches. This
will help the current effort to libify merge-recursive.c.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---
 merge-recursive.c | 106 ++++++++++++++++++++++++++++--------------------------
 1 file changed, 56 insertions(+), 50 deletions(-)

diff --git a/merge-recursive.c b/merge-recursive.c
index 2d4cb80..e1cea96 100644
--- a/merge-recursive.c
+++ b/merge-recursive.c
@@ -885,47 +885,47 @@ static int merge_3way(struct merge_options *o,
 	return merge_status;
 }
 
-static struct merge_file_info merge_file_1(struct merge_options *o,
+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 *branch1,
-					   const char *branch2)
+					   const char *branch2,
+					   struct merge_file_info *result)
 {
-	struct merge_file_info result;
-	result.merge = 0;
-	result.clean = 1;
+	result->merge = 0;
+	result->clean = 1;
 
 	if ((S_IFMT & a->mode) != (S_IFMT & b->mode)) {
-		result.clean = 0;
+		result->clean = 0;
 		if (S_ISREG(a->mode)) {
-			result.mode = a->mode;
-			oidcpy(&result.oid, &a->oid);
+			result->mode = a->mode;
+			oidcpy(&result->oid, &a->oid);
 		} else {
-			result.mode = b->mode;
-			oidcpy(&result.oid, &b->oid);
+			result->mode = b->mode;
+			oidcpy(&result->oid, &b->oid);
 		}
 	} else {
 		if (!oid_eq(&a->oid, &one->oid) && !oid_eq(&b->oid, &one->oid))
-			result.merge = 1;
+			result->merge = 1;
 
 		/*
 		 * Merge modes
 		 */
 		if (a->mode == b->mode || a->mode == one->mode)
-			result.mode = b->mode;
+			result->mode = b->mode;
 		else {
-			result.mode = a->mode;
+			result->mode = a->mode;
 			if (b->mode != one->mode) {
-				result.clean = 0;
-				result.merge = 1;
+				result->clean = 0;
+				result->merge = 1;
 			}
 		}
 
 		if (oid_eq(&a->oid, &b->oid) || oid_eq(&a->oid, &one->oid))
-			oidcpy(&result.oid, &b->oid);
+			oidcpy(&result->oid, &b->oid);
 		else if (oid_eq(&b->oid, &one->oid))
-			oidcpy(&result.oid, &a->oid);
+			oidcpy(&result->oid, &a->oid);
 		else if (S_ISREG(a->mode)) {
 			mmbuffer_t result_buf;
 			int merge_status;
@@ -937,64 +937,66 @@ static struct merge_file_info merge_file_1(struct merge_options *o,
 				die(_("Failed to execute internal merge"));
 
 			if (write_sha1_file(result_buf.ptr, result_buf.size,
-					    blob_type, result.oid.hash))
+					    blob_type, result->oid.hash))
 				die(_("Unable to add %s to database"),
 				    a->path);
 
 			free(result_buf.ptr);
-			result.clean = (merge_status == 0);
+			result->clean = (merge_status == 0);
 		} else if (S_ISGITLINK(a->mode)) {
-			result.clean = merge_submodule(result.oid.hash,
+			result->clean = merge_submodule(result->oid.hash,
 						       one->path,
 						       one->oid.hash,
 						       a->oid.hash,
 						       b->oid.hash,
 						       !o->call_depth);
 		} else if (S_ISLNK(a->mode)) {
-			oidcpy(&result.oid, &a->oid);
+			oidcpy(&result->oid, &a->oid);
 
 			if (!oid_eq(&a->oid, &b->oid))
-				result.clean = 0;
+				result->clean = 0;
 		} else
 			die("BUG: unsupported object type in the tree");
 	}
 
-	return result;
+	return 0;
 }
 
-static struct merge_file_info
-merge_file_special_markers(struct merge_options *o,
+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 *branch1,
 			   const char *filename1,
 			   const char *branch2,
-			   const char *filename2)
+			   const char *filename2,
+			   struct merge_file_info *mfi)
 {
 	char *side1 = NULL;
 	char *side2 = NULL;
-	struct merge_file_info mfi;
+	int ret;
 
 	if (filename1)
 		side1 = xstrfmt("%s:%s", branch1, filename1);
 	if (filename2)
 		side2 = xstrfmt("%s:%s", branch2, filename2);
 
-	mfi = merge_file_1(o, one, a, b,
-			   side1 ? side1 : branch1, side2 ? side2 : branch2);
+	ret = merge_file_1(o, one, a, b,
+			   side1 ? side1 : branch1,
+			   side2 ? side2 : branch2, mfi);
 	free(side1);
 	free(side2);
-	return mfi;
+	return ret;
 }
 
-static struct merge_file_info merge_file_one(struct merge_options *o,
+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)
+					 const char *branch2,
+					 struct merge_file_info *mfi)
 {
 	struct diff_filespec one, a, b;
 
@@ -1005,7 +1007,7 @@ static struct merge_file_info merge_file_one(struct merge_options *o,
 	a.mode = a_mode;
 	oidcpy(&b.oid, b_oid);
 	b.mode = b_mode;
-	return merge_file_1(o, &one, &a, &b, branch1, branch2);
+	return merge_file_1(o, &one, &a, &b, branch1, branch2, mfi);
 }
 
 static void handle_change_delete(struct merge_options *o,
@@ -1178,11 +1180,12 @@ static void conflict_rename_rename_1to2(struct merge_options *o,
 		struct merge_file_info mfi;
 		struct diff_filespec other;
 		struct diff_filespec *add;
-		mfi = merge_file_one(o, one->path,
+		if (merge_file_one(o, one->path,
 				 &one->oid, one->mode,
 				 &a->oid, a->mode,
 				 &b->oid, b->mode,
-				 ci->branch1, ci->branch2);
+				 ci->branch1, ci->branch2, &mfi))
+			return;
 		/*
 		 * FIXME: For rename/add-source conflicts (if we could detect
 		 * such), this is wrong.  We should instead find a unique
@@ -1236,12 +1239,13 @@ static void conflict_rename_rename_2to1(struct merge_options *o,
 	remove_file(o, 1, a->path, o->call_depth || would_lose_untracked(a->path));
 	remove_file(o, 1, b->path, o->call_depth || would_lose_untracked(b->path));
 
-	mfi_c1 = merge_file_special_markers(o, a, c1, &ci->ren1_other,
-					    o->branch1, c1->path,
-					    o->branch2, ci->ren1_other.path);
-	mfi_c2 = merge_file_special_markers(o, b, &ci->ren2_other, c2,
-					    o->branch1, ci->ren2_other.path,
-					    o->branch2, c2->path);
+	if (merge_file_special_markers(o, a, c1, &ci->ren1_other,
+				       o->branch1, c1->path,
+				       o->branch2, ci->ren1_other.path, &mfi_c1) ||
+	    merge_file_special_markers(o, b, &ci->ren2_other, c2,
+				       o->branch1, ci->ren2_other.path,
+				       o->branch2, c2->path, &mfi_c2))
+		return;
 
 	if (o->call_depth) {
 		/*
@@ -1464,12 +1468,13 @@ static int process_renames(struct merge_options *o,
 				       ren1_dst, branch2);
 				if (o->call_depth) {
 					struct merge_file_info mfi;
-					mfi = 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);
+					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))
+						return -1;
 					output(o, 1, _("Adding merged %s"), ren1_dst);
 					update_file(o, 0, &mfi.oid,
 						    mfi.mode, ren1_dst);
@@ -1627,9 +1632,10 @@ static int merge_content(struct merge_options *o,
 		if (dir_in_way(path, !o->call_depth))
 			df_conflict_remains = 1;
 	}
-	mfi = merge_file_special_markers(o, &one, &a, &b,
-					 o->branch1, path1,
-					 o->branch2, path2);
+	if (merge_file_special_markers(o, &one, &a, &b,
+				       o->branch1, path1,
+				       o->branch2, path2, &mfi))
+		return -1;
 
 	if (mfi.clean && !df_conflict_remains &&
 	    oid_eq(&mfi.oid, a_oid) && mfi.mode == a_mode) {
-- 
2.9.0.281.g286a8d9