made builder required (#51993)

2020-03-09 14:01:01 -05:00 · 2020-03-09 14:01:01 -05:00 · 31df1d459e
commit 31df1d459e
parent 5b0a79dbdb
1 changed files with 3 additions and 2 deletions
--- a/packages/flutter/lib/src/widgets/layout_builder.dart
+++ b/packages/flutter/lib/src/widgets/layout_builder.dart
@ -202,8 +202,9 @@ class LayoutBuilder extends ConstrainedLayoutBuilder<BoxConstraints> {
  /// The [builder] argument must not be null.
  const LayoutBuilder({
    Key key,
-    LayoutWidgetBuilder builder,
-  }) : super(key: key, builder: builder);
+    @required LayoutWidgetBuilder builder,
+  }) : assert(builder != null),
+       super(key: key, builder: builder);

  @override
  LayoutWidgetBuilder get builder => super.builder;