cons tearoff support for unnecessary_parenthesis (dart-archive/linter#2926)

Author: pq

lib/src/rules/unnecessary_parenthesis.dart

@@ -48,8 +48,9 @@ class _Visitor extends SimpleAstVisitor<void> {
 
   @override
   void visitParenthesizedExpression(ParenthesizedExpression node) {
-    if (node.expression is SimpleIdentifier) {
-      var parent = node.parent;
+    var parent = node.parent;
+    var expression = node.expression;
+    if (expression is SimpleIdentifier) {
       if (parent is PropertyAccess) {
         if (parent.propertyName.name == 'hashCode' ||
             parent.propertyName.name == 'runtimeType') {
@@ -67,15 +68,21 @@ class _Visitor extends SimpleAstVisitor<void> {
       return;
     }
 
-    var parent = node.parent;
+    if (expression is ConstructorReference) {
+      if (parent is! FunctionExpressionInvocation ||
+          parent.typeArguments == null) {
+        rule.reportLint(node);
+        return;
+      }
+    }
 
     if (parent is ParenthesizedExpression) {
       rule.reportLint(node);
       return;
     }
 
     // `a..b=(c..d)` is OK.
-    if (node.expression is CascadeExpression ||
+    if (expression is CascadeExpression ||
         node.thisOrAncestorMatching(
                 (n) => n is Statement || n is CascadeExpression)
             is CascadeExpression) {

test_data/rules/experiments/constructor_tearoffs/rules/unnecessary_parenthesis.dart

@@ -0,0 +1,108 @@
+// Copyright (c) 2021, the Dart project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+// test w/ `dart test -N unnecessary_parenthesis.dart`
+
+import 'dart:async';
+
+class D {
+  D.d([int? x, int? y]);
+}
+
+/// https://github.com/dart-lang/linter/issues/2907
+void constructorTearOffs() {
+  var makeD = D.d;
+  (makeD)(1); // LINT
+  (D.d)(1); // LINT
+  (List<int>.filled)(3, 0); // LINT
+  (List.filled)<int>(3, 0); // OK
+  var tearoff = (List<int>.filled); // LINT
+  (List<int>).toString(); //OK
+}
+
+var a, b, c, d;
+
+main() async {
+  1; // OK
+  (1); // LINT
+  print(1); // OK
+  print((1)); // LINT
+  if (a && b || c && d) true; // OK
+  // OK because it may be hard to know all of the precedence rules.
+  if ((a && b) || c && d) true; // OK
+  (await new Future.value(1)).toString(); // OK
+  ('' as String).toString(); // OK
+  !(true as bool); // OK
+  a = (a); // LINT
+  (a) ? true : false; // LINT
+  true ? (a) : false; // LINT
+  true ? true : (a); // LINT
+  // OK because it is unobvious that the space-involving ternary binds tighter
+  // than the cascade.
+  (true ? [] : [])..add(''); // OK
+  (a ?? true) ? true : true; // OK
+  true ? [] : []
+    ..add(''); // OK
+  m(p: (1 + 3)); // LINT
+  (a++).toString(); // OK
+
+  // OK because it is unobvious where cascades fall in precedence.
+  a..b = (c..d); // OK
+  a.b = (c..d); // OK
+  a..b = (c.d); // OK
+  ((x) => x is bool ? x : false)(a); // OK
+  (fn)(a); // LINT
+
+  // OK because unary operators mixed with space-separated tokens may have
+  // unexpected ordering.
+  !(const [7].contains(42)); // OK
+  !(new List(3).contains(42)); // OK
+  !(await Future.value(false)); // OK
+  -(new List(3).length); // OK
+  !(new List(3).length.isEven); // OK
+  -(new List(3).length.abs().abs().abs()); // OK
+  -(new List(3).length.sign.sign.sign); // OK
+  !(const [7]).contains(42); // OK
+
+  // OK because some methods are defined on Type, but removing the parentheses
+  // would attempt to call a _static_ method on the target.
+  (String).hashCode;
+  (int).runtimeType;
+  (bool).noSuchMethod();
+  (double).toString();
+
+  ({false: 'false', true: 'true'}).forEach((k, v) => print('$k: $v'));
+  ({false, true}).forEach(print);
+  ({false, true}).length;
+  print(({1, 2, 3}).length); // LINT
+  ([false, true]).forEach(print); // LINT
+}
+
+m({p}) => null;
+
+bool Function(dynamic) get fn => (x) => x is bool ? x : false;
+
+class ClassWithFunction {
+  Function f;
+  int number;
+
+  ClassWithFunction.named(int a) : this.number = (a + 2); // LINT
+  // https://github.com/dart-lang/linter/issues/1473
+  ClassWithFunction.named2(Function value) : this.f = (value ?? (_) => 42); // OK
+}
+
+class ClassWithClassWithFunction {
+  ClassWithFunction c;
+
+  // https://github.com/dart-lang/linter/issues/1395
+  ClassWithClassWithFunction() : c = (ClassWithFunction()..f = () => 42); // OK
+}
+
+class UnnecessaryParenthesis {
+  ClassWithClassWithFunction c;
+
+  UnnecessaryParenthesis()
+      : c = (ClassWithClassWithFunction()
+          ..c = ClassWithFunction().f = () => 42); // OK
+}