Merge branch 'jc/ll-merge-binary-ours'

"git merge -Xtheirs" did not help content-level merge of binary
files; it should just take their version.  Also "*.jpg binary" in
the attributes did not imply they should use the binary ll-merge
driver.

* jc/ll-merge-binary-ours:
  ll-merge: warn about inability to merge binary files only when we can't
  attr: "binary" attribute should choose built-in "binary" merge driver
  merge: teach -Xours/-Xtheirs to binary ll-merge driver

Documentation/gitattributes.txt

@@ -927,7 +927,7 @@ file at the toplevel (i.e. not in any subdirectory).  The built-in
 macro attribute "binary" is equivalent to:
 
 ------------
-[attr]binary -diff -text
+[attr]binary -diff -merge -text
 ------------
 
 

Documentation/merge-strategies.txt

@@ -32,13 +32,14 @@ ours;;
 	This option forces conflicting hunks to be auto-resolved cleanly by
 	favoring 'our' version.  Changes from the other tree that do not
 	conflict with our side are reflected to the merge result.
+	For a binary file, the entire contents are taken from our side.
 +
 This should not be confused with the 'ours' merge strategy, which does not
 even look at what the other tree contains at all.  It discards everything
 the other tree did, declaring 'our' history contains all that happened in it.
 
 theirs;;
-	This is opposite of 'ours'.
+	This is the opposite of 'ours'.
 
 patience;;
 	With this option, 'merge-recursive' spends a little extra time

attr.c

@@ -306,7 +306,7 @@ static void free_attr_elem(struct attr_stack *e)
 }
 
 static const char *builtin_attr[] = {
-	"[attr]binary -diff -text",
+	"[attr]binary -diff -merge -text",
 	NULL,
 };
 

ll-merge.c

@@ -35,7 +35,7 @@ struct ll_merge_driver {
  */
 static int ll_binary_merge(const struct ll_merge_driver *drv_unused,
 			   mmbuffer_t *result,
-			   const char *path_unused,
+			   const char *path,
 			   mmfile_t *orig, const char *orig_name,
 			   mmfile_t *src1, const char *name1,
 			   mmfile_t *src2, const char *name2,
@@ -46,16 +46,34 @@ static int ll_binary_merge(const struct ll_merge_driver *drv_unused,
 	assert(opts);
 
 	/*
-	 * The tentative merge result is "ours" for the final round,
+	 * The tentative merge result is the or common ancestor for an internal merge.
-	 * or common ancestor for an internal merge.  Still return
-	 * "conflicted merge" status.
 	 */
-	stolen = opts->virtual_ancestor ? orig : src1;
+	if (opts->virtual_ancestor) {
+		stolen = orig;
+	} else {
+		switch (opts->variant) {
+		default:
+			warning("Cannot merge binary files: %s (%s vs. %s)",
+				path, name1, name2);
+			/* fallthru */
+		case XDL_MERGE_FAVOR_OURS:
+			stolen = src1;
+			break;
+		case XDL_MERGE_FAVOR_THEIRS:
+			stolen = src2;
+			break;
+		}
+	}
 
 	result->ptr = stolen->ptr;
 	result->size = stolen->size;
 	stolen->ptr = NULL;
-	return 1;
+
+	/*
+	 * With -Xtheirs or -Xours, we have cleanly merged;
+	 * otherwise we got a conflict.
+	 */
+	return (opts->variant ? 0 : 1);
 }
 
 static int ll_xdl_merge(const struct ll_merge_driver *drv_unused,
@@ -73,8 +91,6 @@ static int ll_xdl_merge(const struct ll_merge_driver *drv_unused,
 	if (buffer_is_binary(orig->ptr, orig->size) ||
 	    buffer_is_binary(src1->ptr, src1->size) ||
 	    buffer_is_binary(src2->ptr, src2->size)) {
-		warning("Cannot merge binary files: %s (%s vs. %s)",
-			path, name1, name2);
 		return ll_binary_merge(drv_unused, result,
 				       path,
 				       orig, orig_name,

t/t6037-merge-ours-theirs.sh

@@ -53,7 +53,19 @@ test_expect_success 'recursive favouring ours' '
 	! grep 1 file
 '
 
-test_expect_success 'pull with -X' '
+test_expect_success 'binary file with -Xours/-Xtheirs' '
+	echo file binary >.gitattributes &&
+
+	git reset --hard master &&
+	git merge -s recursive -X theirs side &&
+	git diff --exit-code side HEAD -- file &&
+
+	git reset --hard master &&
+	git merge -s recursive -X ours side &&
+	git diff --exit-code master HEAD -- file
+'
+
+test_expect_success 'pull passes -X to underlying merge' '
 	git reset --hard master && git pull -s recursive -Xours . side &&
 	git reset --hard master && git pull -s recursive -X ours . side &&
 	git reset --hard master && git pull -s recursive -Xtheirs . side &&