zig fmt: fix comment after if before another if

std/segmented_list.zig

@@ -298,21 +298,27 @@ pub fn SegmentedList(comptime T: type, comptime prealloc_item_count: usize) type
 
                 return &it.list.dynamic_segments[it.shelf_index][it.box_index];
             }
+
+            pub fn set(it: &Iterator, index: usize) void {
+                if (index < prealloc_item_count) {
+                    it.index = index;
+                    return;
+                }
+                it.shelf_index = shelfIndex(index);
+                it.box_index = boxIndex(index, it.shelf_index);
+                it.shelf_size = shelfSize(it.shelf_index);
+            }
         };
 
         pub fn iterator(self: &Self, start_index: usize) Iterator {
             var it = Iterator {
                 .list = self,
-                .index = start_index,
+                .index = undefined,
                 .shelf_index = undefined,
                 .box_index = undefined,
                 .shelf_size = undefined,
             };
-            if (start_index >= prealloc_item_count) {
-                it.shelf_index = shelfIndex(start_index);
-                it.box_index = boxIndex(start_index, it.shelf_index);
-                it.shelf_size = shelfSize(it.shelf_index);
-            }
+            it.set(start_index);
             return it;
         }
     };

std/zig/parse.zig

@@ -1017,7 +1017,11 @@ pub fn parse(allocator: &mem.Allocator, source: []const u8) !ast.Tree {
                 continue;
             },
             State.Else => |dest| {
-                while (try eatLineComment(arena, &tok_it, &tree)) |_| { }
+                const old_index = tok_it.index;
+                var need_index_restore = false;
+                while (try eatLineComment(arena, &tok_it, &tree)) |_| {
+                    need_index_restore = true;
+                }
                 if (eatToken(&tok_it, &tree, Token.Id.Keyword_else)) |else_token| {
                     const node = try arena.construct(ast.Node.Else {
                         .base = ast.Node {.id = ast.Node.Id.Else },
@@ -1031,6 +1035,9 @@ pub fn parse(allocator: &mem.Allocator, source: []const u8) !ast.Tree {
                     try stack.append(State { .Payload = OptionalCtx { .Optional = &node.payload } });
                     continue;
                 } else {
+                    if (need_index_restore) {
+                        tok_it.set(old_index);
+                    }
                     continue;
                 }
             },

std/zig/parser_test.zig

@@ -1,3 +1,18 @@
+test "zig fmt: comment after if before another if" {
+    try testCanonical(
+        \\test "aoeu" {
+        \\    if (x) {
+        \\        foo();
+        \\    }
+        \\    // comment
+        \\    if (x) {
+        \\        bar();
+        \\    }
+        \\}
+        \\
+    );
+}
+
 test "zig fmt: line comment between if block and else keyword" {
     try testTransform(
         \\test "aoeu" {