[DAS] Fixes switch_on_type for dynamic

Fixes: https://github.com/dart-lang/sdk/issues/61355
Change-Id: I306e825a20a93910a72c3208596f6d21d82d1ef3
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/445921
Auto-Submit: Felipe Morschel <git@fmorschel.dev>
Reviewed-by: Samuel Rawlins <srawlins@google.com>
Commit-Queue: Brian Wilkerson <brianwilkerson@google.com>
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
Commit-Queue: Samuel Rawlins <srawlins@google.com>

pkg/linter/lib/src/rules/switch_on_type.dart

@@ -69,7 +69,7 @@ class _Visitor extends SimpleAstVisitor<void> {
 
   /// Returns `true` if the [type] is assignable to [Type].
   bool _isAssignableToType(DartType? type) {
-    if (type == null) return false;
+    if (type == null || type is DynamicType) return false;
     return context.typeSystem.isAssignableTo(type, _typeType);
   }
 

pkg/linter/test/rules/switch_on_type_test.dart

@@ -60,6 +60,14 @@ void f(Type t) {
     );
   }
 
+  Future<void> test_dynamic() async {
+    await assertNoDiagnostics('''
+void foo(dynamic a) {
+  switch (a) {}
+}
+''');
+  }
+
   Future<void> test_functionToString() async {
     await assertNoDiagnostics('''
 void f() {