Analyzer: print constructor name when constructor returns invalid type

Fixes #27387

Change-Id: I8ce81bab4c4601c5157977d3f43f73903dae7f8b
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/151200
Commit-Queue: Samuel Rawlins <[email protected]>
Reviewed-by: Brian Wilkerson <[email protected]>

Author: srawlins

pkg/analyzer/lib/error/error.dart

@@ -706,6 +706,7 @@ const List<ErrorCode> errorCodeValues = [
   // ignore: deprecated_member_use_from_same_package
   StaticTypeWarningCode.RETURN_OF_INVALID_TYPE,
   StaticTypeWarningCode.RETURN_OF_INVALID_TYPE_FROM_CLOSURE,
+  StaticTypeWarningCode.RETURN_OF_INVALID_TYPE_FROM_CONSTRUCTOR,
   StaticTypeWarningCode.RETURN_OF_INVALID_TYPE_FROM_FUNCTION,
   StaticTypeWarningCode.RETURN_OF_INVALID_TYPE_FROM_METHOD,
   StaticTypeWarningCode.TYPE_PARAMETER_SUPERTYPE_OF_ITS_BOUND,

pkg/analyzer/lib/src/error/codes.dart

@@ -7340,6 +7340,20 @@ class StaticTypeWarningCode extends AnalyzerErrorCode {
               "context.",
           hasPublishedDocs: true);
 
+  /**
+   * Parameters:
+   * 0: the return type as declared in the return statement
+   * 1: the expected return type as defined by the enclosing class
+   * 2: the name of the constructor
+   */
+  static const StaticTypeWarningCode RETURN_OF_INVALID_TYPE_FROM_CONSTRUCTOR =
+      StaticTypeWarningCodeWithUniqueName(
+          'RETURN_OF_INVALID_TYPE',
+          'StaticTypeWarningCode.RETURN_OF_INVALID_TYPE_FROM_CONSTRUCTOR',
+          "A value of type '{0}' can't be returned from constructor '{2}' "
+              "because it has a return type of '{1}'.",
+          hasPublishedDocs: true);
+
   /**
    * Parameters:
    * 0: the return type as declared in the return statement

pkg/analyzer/lib/src/error/return_type_verifier.dart

@@ -141,7 +141,19 @@ class ReturnTypeVerifier {
 
     void reportTypeError() {
       String displayName = enclosingExecutable.element.displayName;
-      if (displayName.isEmpty) {
+      if (enclosingExecutable.isConstructor) {
+        var constructor = enclosingExecutable.element as ConstructorElement;
+        var className = constructor.enclosingElement.displayName;
+        var constructorBaseName = constructor.displayName;
+        var constructorName = constructorBaseName.isEmpty
+            ? className
+            : '$className.$constructorBaseName';
+        _errorReporter.reportErrorForNode(
+          StaticTypeWarningCode.RETURN_OF_INVALID_TYPE_FROM_CONSTRUCTOR,
+          expression,
+          [S, T, constructorName],
+        );
+      } else if (displayName.isEmpty) {
         _errorReporter.reportErrorForNode(
           StaticTypeWarningCode.RETURN_OF_INVALID_TYPE_FROM_CLOSURE,
           expression,
@@ -237,7 +249,19 @@ class ReturnTypeVerifier {
 
     void reportTypeError() {
       String displayName = enclosingExecutable.element.displayName;
-      if (displayName.isEmpty) {
+      if (enclosingExecutable.isConstructor) {
+        var constructor = enclosingExecutable.element as ConstructorElement;
+        var className = constructor.enclosingElement.displayName;
+        var constructorBaseName = constructor.displayName;
+        var constructorName = constructorBaseName.isEmpty
+            ? className
+            : '$className.$constructorBaseName';
+        _errorReporter.reportErrorForNode(
+          StaticTypeWarningCode.RETURN_OF_INVALID_TYPE_FROM_CONSTRUCTOR,
+          expression,
+          [S, T, constructorName],
+        );
+      } else if (displayName.isEmpty) {
         _errorReporter.reportErrorForNode(
           StaticTypeWarningCode.RETURN_OF_INVALID_TYPE_FROM_CLOSURE,
           expression,

pkg/analyzer/lib/src/generated/error_verifier.dart

@@ -71,6 +71,8 @@ class EnclosingExecutableContext {
 
   EnclosingExecutableContext.empty() : this(null);
 
+  bool get isConstructor => element is ConstructorElement;
+
   bool get isMethod => element is MethodElement;
 
   bool get isSynchronous => !isAsynchronous;

pkg/analyzer/test/src/diagnostics/return_of_invalid_type_test.dart

@@ -17,6 +17,39 @@ main() {
 
 @reflectiveTest
 class ReturnOfInvalidTypeTest extends DriverResolutionTest {
+  test_closure() async {
+    await assertErrorsInCode('''
+typedef Td = int Function();
+Td f() {
+  return () => "hello";
+}
+''', [
+      error(StaticTypeWarningCode.RETURN_OF_INVALID_TYPE_FROM_CLOSURE, 53, 7),
+    ]);
+  }
+
+  test_factoryConstructor_named() async {
+    await assertErrorsInCode('''
+class C {
+  factory C.named() => 7;
+}
+''', [
+      error(
+          StaticTypeWarningCode.RETURN_OF_INVALID_TYPE_FROM_CONSTRUCTOR, 33, 1),
+    ]);
+  }
+
+  test_factoryConstructor_unnamed() async {
+    await assertErrorsInCode('''
+class C {
+  factory C() => 7;
+}
+''', [
+      error(
+          StaticTypeWarningCode.RETURN_OF_INVALID_TYPE_FROM_CONSTRUCTOR, 27, 1),
+    ]);
+  }
+
   test_function_async_block__to_Future_void() async {
     await assertNoErrorsInCode(r'''
 Future<void> f1() async {}

tests/language/factory/return_type_checked_test.dart

@@ -7,7 +7,7 @@ import "package:expect/expect.dart";
 class A {
   factory A() => 42;
   //             ^^
-  // [analyzer] STATIC_TYPE_WARNING.RETURN_OF_INVALID_TYPE_FROM_CLOSURE
+  // [analyzer] STATIC_TYPE_WARNING.RETURN_OF_INVALID_TYPE
   // [cfe] A value of type 'int' can't be assigned to a variable of type 'A'.
 }
 

tests/language_2/factory/return_type_checked_test.dart

@@ -7,7 +7,7 @@ import "package:expect/expect.dart";
 class A {
   factory A() => 42;
   //             ^^
-  // [analyzer] STATIC_TYPE_WARNING.RETURN_OF_INVALID_TYPE_FROM_CLOSURE
+  // [analyzer] STATIC_TYPE_WARNING.RETURN_OF_INVALID_TYPE
   // [cfe] A value of type 'int' can't be assigned to a variable of type 'A'.
 }