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

// Copyright (c) 2020, 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.

import 'package:analyzer/src/error/codes.dart';
import 'package:test_reflective_loader/test_reflective_loader.dart';

import '../dart/resolution/context_collection_resolution.dart';

main() {
  defineReflectiveSuite(() {
    defineReflectiveTests(CouldNotInferTest);
    defineReflectiveTests(CouldNotInferWithNullSafetyTest);
  });
}

@reflectiveTest
class CouldNotInferTest extends PubPackageResolutionTest {
  test_constructors_inferenceFBounded() async {
    await assertErrorsInCode('''
class C<T> {}

class P<T extends C<T>, U extends C<U>> {
  T t;
  U u;
  P(this.t, this.u);
  P._();
  P<U, T> get reversed => new P(u, t);
}

main() {
  P._();
}
''', [
      error(CompileTimeErrorCode.COULD_NOT_INFER, 154, 3),
      error(CompileTimeErrorCode.TYPE_ARGUMENT_NOT_MATCHING_BOUNDS, 154, 1),
      error(CompileTimeErrorCode.COULD_NOT_INFER, 154, 3),
    ]);
  }

  test_constructors_inferFromArguments_argumentNotAssignable() async {
    await assertErrorsInCode('''
class A {}

typedef T F<T>();

class C<T extends A> {
  C(F<T> f);
}

class NotA {}
NotA myF() => null;

main() {
  var x = C(myF);
}
''', [
      error(HintCode.UNUSED_LOCAL_VARIABLE, 120, 1),
      error(CompileTimeErrorCode.TYPE_ARGUMENT_NOT_MATCHING_BOUNDS, 124, 1),
      error(CompileTimeErrorCode.COULD_NOT_INFER, 124, 1),
    ]);
  }

  test_downwardInference_fixes_noUpwardsErrors() async {
    await assertErrorsInCode(r'''
import 'dart:math';
// T max<T extends num>(T x, T y);
main() {
  num x;
  dynamic y;

  num a = max(x, y);
  Object b = max(x, y);
  dynamic c = max(x, y);
  var d = max(x, y);
}
''', [
      error(HintCode.UNUSED_LOCAL_VARIABLE, 93, 1),
      error(HintCode.UNUSED_LOCAL_VARIABLE, 117, 1),
      error(HintCode.UNUSED_LOCAL_VARIABLE, 142, 1),
      error(CompileTimeErrorCode.COULD_NOT_INFER, 146, 3),
      error(HintCode.UNUSED_LOCAL_VARIABLE, 163, 1),
      error(CompileTimeErrorCode.COULD_NOT_INFER, 167, 3),
    ]);
  }

  test_function() async {
    await assertErrorsInCode(r'''
T f<T>(T t) => null;
main() { f(<S>(S s) => s); }
''', [
      error(CompileTimeErrorCode.COULD_NOT_INFER, 30, 1),
    ]);
  }

  test_functionType() async {
    await assertErrorsInCode('''
T Function<T>(T) f;
main() { f(<S>(S s) => s); }
''', [
      error(CompileTimeErrorCode.COULD_NOT_INFER, 29, 1),
    ]);
  }

  test_functionType_allSameSubtype() async {
    await assertNoErrorsInCode(r'''
external T f<T extends num>(T a, T b);
void g(int cb(int a, int b)) {}
void main() {
  g(f);
}
''');
  }

  test_functionType_parameterIsBound_returnIsBound() async {
    await assertNoErrorsInCode(r'''
external T f<T extends num>(T a, T b);
void g(num cb(num a, num b)) {}
void main() {
  g(f);
}
''');
  }

  test_functionType_parameterIsObject_returnIsBound() async {
    await assertErrorsInCode('''
external T f<T extends num>(T a, T b);
void g(num cb(Object a, Object b)) {}
void main() {
  g(f);
}
''', [
      error(CompileTimeErrorCode.COULD_NOT_INFER, 95, 1),
      error(CompileTimeErrorCode.INVALID_CAST_FUNCTION, 95, 1),
    ]);
  }

  test_functionType_parameterIsObject_returnIsBound_prefixedFunction() async {
    newFile('$testPackageLibPath/a.dart', content: '''
external T f<T extends num>(T a, T b);
''');
    await assertErrorsInCode('''
import 'a.dart' as a;
void g(num cb(Object a, Object b)) {}
void main() {
  g(a.f);
}
''', [
      error(CompileTimeErrorCode.COULD_NOT_INFER, 78, 3),
      error(CompileTimeErrorCode.INVALID_CAST_FUNCTION, 78, 3),
    ]);
  }

  test_functionType_parameterIsObject_returnIsSubtype() async {
    await assertErrorsInCode('''
external T f<T extends num>(T a, T b);
void g(int cb(Object a, Object b)) {}
void main() {
  g(f);
}
''', [
      error(CompileTimeErrorCode.COULD_NOT_INFER, 95, 1),
      error(CompileTimeErrorCode.INVALID_CAST_FUNCTION, 95, 1),
    ]);
  }

  test_functionType_parameterIsObject_returnIsSubtype_tearOff() async {
    await assertErrorsInCode('''
class C {
  T m<T extends num>(T x, T y) {
    throw 'error';
  }
}
void g(int cb(Object a, Object b)) {}
void main() {
  g(C().m);
}
''', [
      error(CompileTimeErrorCode.COULD_NOT_INFER, 124, 5),
    ]);
  }

  test_functionType_parameterIsSubtype_returnIsBound() async {
    await assertNoErrorsInCode(r'''
external T f<T extends num>(T a, T b);
void g(num cb(int a, int b)) {}
void main() {
  g(f);
}
''');
  }

  test_functionType_parameterIsSubtype_returnIsObject() async {
    await assertNoErrorsInCode('''
external T f<T extends num>(T a, T b);
void g(Object cb(int a, int b)) {}
void main() {
  g(f);
}
''');
  }

  test_functionType_parametersAreSubtypes_returnIsBound() async {
    await assertNoErrorsInCode('''
external T f<T extends num>(T a, T b);
void g(num cb(int a, double b)) {}
void main() {
  g(f);
}
''');
  }

  test_functionType_parametersAreSubtypes_returnIsOne() async {
    await assertErrorsInCode('''
external T f<T extends num>(T a, T b);
void g(int cb(int a, double b)) {}
void main() {
  g(f);
}
''', [
      error(CompileTimeErrorCode.COULD_NOT_INFER, 92, 1),
      error(CompileTimeErrorCode.ARGUMENT_TYPE_NOT_ASSIGNABLE, 92, 1),
    ]);
  }

  test_genericMethods_correctlyRecognizeGenericUpperBound() async {
    // Regression test for https://github.com/dart-lang/sdk/issues/25740.
    await assertErrorsInCode(r'''
class Foo<T extends Pattern> {
  U method<U extends T>(U u) => u;
}
main() {
  new Foo<String>().method(42);
}
''', [
      error(CompileTimeErrorCode.COULD_NOT_INFER, 97, 6),
    ]);
  }

  test_method() async {
    await assertErrorsInCode(r'''
class C {
  T f<T>(T t) => null;
}
main() { new C().f(<S>(S s) => s); }
''', [
      error(CompileTimeErrorCode.COULD_NOT_INFER, 52, 1),
    ]);
  }
}

@reflectiveTest
class CouldNotInferWithNullSafetyTest extends PubPackageResolutionTest
    with WithNullSafetyMixin {
  test_constructor_nullSafe_fromLegacy() async {
    newFile('$testPackageLibPath/a.dart', content: '''
class C<T extends Object> {
  C(T t);
}
''');

    await assertNoErrorsInCode('''
// @dart = 2.8
import 'a.dart';

void f(dynamic a) {
  C(a);
}
''');
  }
}