constructor tearoff fix support for unnecessary_lambdas

Fixes: https://github.com/dart-lang/sdk/issues/47103

Change-Id: I521461a587b9272503772e9b13999d8e4e688352
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/212803
Commit-Queue: Phil Quitslund <pquitslund@google.com>
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>

pkg/analysis_server/lib/src/services/correction/dart/replace_with_tear_off.dart

@@ -43,6 +43,16 @@ class ReplaceWithTearOff extends CorrectionProducer {
             builder.write(utils.getNodeText(expression.function));
           });
         });
+      } else if (expression is InstanceCreationExpression) {
+        await builder.addDartFileEdit(file, (builder) {
+          builder.addReplacement(range.node(ancestor), (builder) {
+            var constructorName = expression.constructorName;
+            builder.write(utils.getNodeText(constructorName));
+            if (constructorName.name == null) {
+              builder.write('.new');
+            }
+          });
+        });
       }
     }
 

pkg/analysis_server/test/src/services/correction/fix/replace_with_tear_off_test.dart

@@ -53,6 +53,121 @@ class ReplaceWithTearOffTest extends FixProcessorLintTest {
   @override
   String get lintCode => LintNames.unnecessary_lambdas;
 
+  Future<void> test_constructorTearOff_named() async {
+    await resolveTestCode('''
+class C {
+  int c;
+  C.create([this.c = 3]);
+}
+
+void f() {
+  var listOfInts = [1, 2, 3];
+  for (var c in listOfInts.map((x) => C.create(x))) {
+    print(c.c);
+  }
+}
+''');
+    await assertHasFix('''
+class C {
+  int c;
+  C.create([this.c = 3]);
+}
+
+void f() {
+  var listOfInts = [1, 2, 3];
+  for (var c in listOfInts.map(C.create)) {
+    print(c.c);
+  }
+}
+''');
+  }
+
+  // @soloTest
+  Future<void> test_constructorTearOff_nameUnnamed() async {
+    await resolveTestCode('''
+class C {
+  int c;
+  C([this.c = 3]);
+}
+
+void f() {
+  var listOfInts = [1, 2, 3];
+  for (var c in listOfInts.map((x) => C.new(x))) {
+    print(c.c);
+  }
+}
+''');
+    await assertHasFix('''
+class C {
+  int c;
+  C([this.c = 3]);
+}
+
+void f() {
+  var listOfInts = [1, 2, 3];
+  for (var c in listOfInts.map(C.new)) {
+    print(c.c);
+  }
+}
+''');
+  }
+
+  Future<void> test_constructorTearOff_oneParameter() async {
+    await resolveTestCode('''
+class C {
+  int c;
+  C([this.c = 3]);
+}
+
+void f() {
+  var listOfInts = [1, 2, 3];
+  for (var c in listOfInts.map((x) => C(x))) {
+    print(c.c);
+  }
+}
+''');
+    await assertHasFix('''
+class C {
+  int c;
+  C([this.c = 3]);
+}
+
+void f() {
+  var listOfInts = [1, 2, 3];
+  for (var c in listOfInts.map(C.new)) {
+    print(c.c);
+  }
+}
+''');
+  }
+
+  Future<void> test_constructorTearOff_zeroParameters() async {
+    await resolveTestCode('''
+typedef Maker = Object Function();
+
+class C {
+  int c;
+  C([this.c = 3]);
+}
+
+var l = <Maker>[
+  () => C(),
+];
+''');
+    await assertHasFix('''
+typedef Maker = Object Function();
+
+class C {
+  int c;
+  C([this.c = 3]);
+}
+
+var l = <Maker>[
+  C.new,
+];
+''');
+  }
+
   Future<void> test_function_oneParameter() async {
     await resolveTestCode('''
 Function f() => (name) {