Merge branch 'jn/unpack-trees-checkout-m-carry-deletion'

"git checkout -m" did not switch to another branch while carrying
the local changes forward when a path was deleted from the index.

* jn/unpack-trees-checkout-m-carry-deletion:
  checkout -m: attempt merge when deletion of path was staged
  unpack-trees: use 'cuddled' style for if-else cascade
  unpack-trees: simplify 'all other failures' case

t/t7201-co.sh

@@ -223,6 +223,23 @@ test_expect_success 'checkout --merge --conflict=diff3 <branch>' '
 	test_cmp two expect
 '
 
+test_expect_success 'switch to another branch while carrying a deletion' '
+
+	git checkout -f master && git reset --hard && git clean -f &&
+	git rm two &&
+
+	test_must_fail git checkout simple 2>errs &&
+	test_i18ngrep overwritten errs &&
+
+	git checkout --merge simple 2>errs &&
+	test_i18ngrep ! overwritten errs &&
+	git ls-files -u &&
+	test_must_fail git cat-file -t :0:two &&
+	test "$(git cat-file -t :1:two)" = blob &&
+	test "$(git cat-file -t :2:two)" = blob &&
+	test_must_fail git cat-file -t :3:two
+'
+
 test_expect_success 'checkout to detach HEAD (with advice declined)' '
 
 	git config advice.detachedHead false &&

unpack-trees.c

@@ -1176,7 +1176,8 @@ int unpack_trees(unsigned len, struct tree_desc *t, struct unpack_trees_options
 static int reject_merge(const struct cache_entry *ce,
 			struct unpack_trees_options *o)
 {
-	return add_rejected_path(o, ERROR_WOULD_OVERWRITE, ce->name);
+	return o->gently ? -1 :
+		add_rejected_path(o, ERROR_WOULD_OVERWRITE, ce->name);
 }
 
 static int same(const struct cache_entry *a, const struct cache_entry *b)
@@ -1631,15 +1632,15 @@ int threeway_merge(const struct cache_entry * const *stages,
 	/* #14, #14ALT, #2ALT */
 	if (remote && !df_conflict_head && head_match && !remote_match) {
 		if (index && !same(index, remote) && !same(index, head))
-			return o->gently ? -1 : reject_merge(index, o);
+			return reject_merge(index, o);
 		return merged_entry(remote, index, o);
 	}
 	/*
 	 * If we have an entry in the index cache, then we want to
 	 * make sure that it matches head.
 	 */
 	if (index && !same(index, head))
-		return o->gently ? -1 : reject_merge(index, o);
+		return reject_merge(index, o);
 
 	if (head) {
 		/* #5ALT, #15 */
@@ -1768,9 +1769,8 @@ int twoway_merge(const struct cache_entry * const *src,
 				else
 					return merged_entry(newtree, current, o);
 			}
-			return o->gently ? -1 : reject_merge(current, o);
-		}
-		else if ((!oldtree && !newtree) || /* 4 and 5 */
+			return reject_merge(current, o);
+		} else if ((!oldtree && !newtree) || /* 4 and 5 */
 			 (!oldtree && newtree &&
 			  same(current, newtree)) || /* 6 and 7 */
 			 (oldtree && newtree &&
@@ -1779,26 +1779,15 @@ int twoway_merge(const struct cache_entry * const *src,
 			  !same(oldtree, newtree) && /* 18 and 19 */
 			  same(current, newtree))) {
 			return keep_entry(current, o);
-		}
-		else if (oldtree && !newtree && same(current, oldtree)) {
+		} else if (oldtree && !newtree && same(current, oldtree)) {
 			/* 10 or 11 */
 			return deleted_entry(oldtree, current, o);
-		}
-		else if (oldtree && newtree &&
+		} else if (oldtree && newtree &&
 			 same(current, oldtree) && !same(current, newtree)) {
 			/* 20 or 21 */
 			return merged_entry(newtree, current, o);
-		}
-		else {
-			/* all other failures */
-			if (oldtree)
-				return o->gently ? -1 : reject_merge(oldtree, o);
-			if (current)
-				return o->gently ? -1 : reject_merge(current, o);
-			if (newtree)
-				return o->gently ? -1 : reject_merge(newtree, o);
-			return -1;
-		}
+		} else
+			return reject_merge(current, o);
 	}
 	else if (newtree) {
 		if (oldtree && !o->initial_checkout) {