[linter] Don't trigger unnecessary_lambdas on deferred constructors

I didn't add this exception to the documentation as it's pretty niche and I'm afraid it might detract from the goal of the lint. Happy to add something if you think it's worth while though :)

Bug reference: #54611

Change-Id: I977be945208aee285f7bb44f73f7953b0646dc14
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/346100
Commit-Queue: Phil Quitslund <[email protected]>
Reviewed-by: Brian Wilkerson <[email protected]>
Reviewed-by: Phil Quitslund <[email protected]>
Auto-Submit: Parker Lougheed <[email protected]>

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

@@ -167,7 +167,9 @@ class _Visitor extends SimpleAstVisitor<void> {
 
   void _visitInstanceCreation(
       InstanceCreationExpression expression, FunctionExpression node) {
-    if (expression.isConst) return;
+    if (expression.isConst || expression.constructorName.type.isDeferred) {
+      return;
+    }
 
     var arguments = expression.argumentList.arguments;
     var parameters = node.parameters?.parameters ?? <FormalParameter>[];

pkg/linter/test/rules/unnecessary_lambdas_test.dart

@@ -32,6 +32,30 @@ var x = [() => const C()];
 ''');
   }
 
+  test_constructorCall_imported() async {
+    newFile('$testPackageLibPath/b.dart', r'''
+class C {}
+''');
+    await assertDiagnostics(r'''
+import 'b.dart' as b;
+
+var x = [() => b.C()];
+''', [
+      lint(32, 11),
+    ]);
+  }
+
+  test_constructorCall_importedDeferred() async {
+    newFile('$testPackageLibPath/b.dart', r'''
+class C {}
+''');
+    await assertNoDiagnostics(r'''
+import 'b.dart' deferred as b;
+
+var x = [() => b.C()];
+''');
+  }
+
   test_constructorCall_matchingArg() async {
     await assertDiagnostics(r'''
 class C {