Only report unnecessary_cast when the cast type is exactly the static…

… type Fixes #44411 Fixes #48984 Fixes #49269 Fixes #49550 Fixes #52086 The "prefer type annotations on local variables over upcasting" that this used to cover can be covered with a new lint rule: https://github.com/dart-lang/linter/issues/3786 Change-Id: I6a112732269e918a7faacc399bccebe13de8462d Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/265420 Reviewed-by: Brian Wilkerson <[email protected]> Commit-Queue: Samuel Rawlins <[email protected]>
dart-lang · Oct 24, 2023 · a6edca6 · a6edca6
1 parent 7ba47c6
commit a6edca6
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Showing 5 changed files with 19 additions and 85 deletions.
diff --git a/pkg/analyzer/lib/src/error/best_practices_verifier.dart b/pkg/analyzer/lib/src/error/best_practices_verifier.dart
@@ -11,7 +11,6 @@ import 'package:analyzer/dart/ast/token.dart';
 import 'package:analyzer/dart/ast/visitor.dart';
 import 'package:analyzer/dart/constant/value.dart';
 import 'package:analyzer/dart/element/element.dart';
-import 'package:analyzer/dart/element/nullability_suffix.dart';
 import 'package:analyzer/dart/element/type.dart';
 import 'package:analyzer/error/error.dart';
 import 'package:analyzer/error/listener.dart';
@@ -1677,39 +1676,10 @@ class BestPracticesVerifier extends RecursiveAstVisitor<void> {
     }
 
     // The cast is necessary.
-    if (!typeSystem.isSubtypeOf(leftType, rightType)) {
+    if (leftType != rightType) {
       return false;
     }
 
-    // Casting from `T*` to `T?` is a way to force `T?`.
-    if (leftType.nullabilitySuffix == NullabilitySuffix.star &&
-        rightType.nullabilitySuffix == NullabilitySuffix.question) {
-      return false;
-    }
-
-    // For `condition ? then : else` the result type is `LUB`.
-    // Casts might be used to consider only a portion of the inheritance tree.
-    var parent = node.parent;
-    if (parent is ConditionalExpression) {
-      var other = node == parent.thenExpression
-          ? parent.elseExpression
-          : parent.thenExpression;
-
-      var currentType = typeSystem.leastUpperBound(
-        node.typeOrThrow,
-        other.typeOrThrow,
-      );
-
-      var typeWithoutCast = typeSystem.leastUpperBound(
-        node.expression.typeOrThrow,
-        other.typeOrThrow,
-      );
-
-      if (typeWithoutCast != currentType) {
-        return false;
-      }
-    }
-
     return true;
   }
 

diff --git a/pkg/analyzer/test/src/diagnostics/cast_from_null_always_fails_test.dart b/pkg/analyzer/test/src/diagnostics/cast_from_null_always_fails_test.dart
@@ -83,13 +83,11 @@ void f<T extends Object>(Null n) {
   }
 
   test_Null_nullable() async {
-    await assertErrorsInCode('''
+    await assertNoErrorsInCode('''
 void f(Null n) {
   n as int?;
 }
-''', [
-      error(WarningCode.UNNECESSARY_CAST, 19, 9),
-    ]);
+''');
   }
 
   test_Null_nullableTypeVariable() async {
@@ -102,15 +100,13 @@ void f<T>(Null n) {
 
   test_Null_preNullSafety() async {
     noSoundNullSafety = false;
-    await assertErrorsInCode('''
+    await assertNoErrorsInCode('''
 // @dart=2.9
 
 void f(Null n) {
   n as int;
 }
-''', [
-      error(WarningCode.UNNECESSARY_CAST, 33, 8),
-    ]);
+''');
   }
 
   test_nullable_nonNullable() async {

diff --git a/pkg/analyzer/test/src/diagnostics/unnecessary_cast_test.dart b/pkg/analyzer/test/src/diagnostics/unnecessary_cast_test.dart
@@ -25,7 +25,8 @@ class A {}
 class B extends A {}
 
 dynamic f(bool c, B x, B y) {
-  return c ? x as A : y;
+  var r = c ? x as A : y;
+  return r;
 }
 ''');
   }
@@ -127,23 +128,19 @@ void f(num Function() a) {
   }
 
   test_function_toSupertype_viaParameter() async {
-    await assertErrorsInCode(r'''
+    await assertNoErrorsInCode(r'''
 void f(void Function(num) a) {
   (a as void Function(int))(3);
 }
-''', [
-      error(WarningCode.UNNECESSARY_CAST, 34, 23),
-    ]);
+''');
   }
 
   test_function_toSupertype_viaReturnType() async {
-    await assertErrorsInCode(r'''
+    await assertNoErrorsInCode(r'''
 void f(int Function() a) {
   (a as num Function())();
 }
-''', [
-      error(WarningCode.UNNECESSARY_CAST, 30, 19),
-    ]);
+''');
   }
 
   test_function_toUnrelated() async {
@@ -171,13 +168,11 @@ void f() {
   }
 
   test_type_supertype() async {
-    await assertErrorsInCode(r'''
+    await assertNoErrorsInCode(r'''
 void f(int a) {
   a as Object;
 }
-''', [
-      error(WarningCode.UNNECESSARY_CAST, 18, 11),
-    ]);
+''');
   }
 
   test_type_type() async {
@@ -191,23 +186,19 @@ void f(num a) {
   }
 
   test_typeParameter_hasBound_same() async {
-    await assertErrorsInCode(r'''
+    await assertNoErrorsInCode(r'''
 void f<T extends num>(T a) {
   a as num;
 }
-''', [
-      error(WarningCode.UNNECESSARY_CAST, 31, 8),
-    ]);
+''');
   }
 
   test_typeParameter_hasBound_subtype() async {
-    await assertErrorsInCode(r'''
+    await assertNoErrorsInCode(r'''
 void f<T extends int>(T a) {
   a as num;
 }
-''', [
-      error(WarningCode.UNNECESSARY_CAST, 31, 8),
-    ]);
+''');
   }
 
   test_typeParameter_hasBound_unrelated() async {
@@ -245,7 +236,6 @@ void f() {
 }
 ''', [
       error(HintCode.IMPORT_OF_LEGACY_LIBRARY_INTO_NULL_SAFE, 7, 8),
-      error(WarningCode.UNNECESSARY_CAST, 39, 8),
     ]);
   }
 

diff --git a/pkg/analyzer/test/src/task/strong/checker_test.dart b/pkg/analyzer/test/src/task/strong/checker_test.dart
@@ -634,13 +634,11 @@ void main() {
       error(CompileTimeErrorCode.INVALID_ASSIGNMENT, 1256, 4),
       error(CompileTimeErrorCode.ARGUMENT_TYPE_NOT_ASSIGNABLE, 1331, 6),
       error(CompileTimeErrorCode.ARGUMENT_TYPE_NOT_ASSIGNABLE, 1359, 4),
-      error(WarningCode.UNNECESSARY_CAST, 1526, 11),
       error(HintCode.UNUSED_LOCAL_VARIABLE, 1591, 1),
       error(CompileTimeErrorCode.INVALID_ASSIGNMENT, 1616, 6),
       error(CompileTimeErrorCode.INVALID_CAST_FUNCTION, 1644, 4),
       error(CompileTimeErrorCode.ARGUMENT_TYPE_NOT_ASSIGNABLE, 1735, 6),
       error(CompileTimeErrorCode.INVALID_CAST_FUNCTION, 1763, 4),
-      error(WarningCode.UNNECESSARY_CAST, 1960, 11),
       error(HintCode.UNUSED_LOCAL_VARIABLE, 2047, 1),
       error(CompileTimeErrorCode.INVALID_ASSIGNMENT, 2088, 2),
       error(CompileTimeErrorCode.INVALID_CAST_FUNCTION, 2100, 4),
@@ -650,7 +648,6 @@ void main() {
       error(CompileTimeErrorCode.ARGUMENT_TYPE_NOT_ASSIGNABLE, 2255, 4),
       error(CompileTimeErrorCode.ARGUMENT_TYPE_NOT_ASSIGNABLE, 2380, 10),
       error(CompileTimeErrorCode.INVALID_CAST_FUNCTION_EXPR, 2400, 22),
-      error(WarningCode.UNNECESSARY_CAST, 2410, 11),
       error(CompileTimeErrorCode.ARGUMENT_TYPE_NOT_ASSIGNABLE, 2450, 4),
       error(HintCode.UNUSED_LOCAL_VARIABLE, 2495, 1),
       error(CompileTimeErrorCode.INVALID_CAST_FUNCTION, 2520, 6),
@@ -661,7 +658,6 @@ void main() {
       error(CompileTimeErrorCode.INVALID_CAST_FUNCTION, 2741, 4),
       error(CompileTimeErrorCode.INVALID_CAST_FUNCTION_EXPR, 2914, 10),
       error(CompileTimeErrorCode.INVALID_CAST_FUNCTION_EXPR, 2952, 22),
-      error(WarningCode.UNNECESSARY_CAST, 2962, 11),
     ]);
   }
 
@@ -1340,30 +1336,20 @@ void main() {
       error(HintCode.UNUSED_LOCAL_VARIABLE, 192, 1),
       error(CompileTimeErrorCode.INVALID_ASSIGNMENT, 222, 7),
       error(CompileTimeErrorCode.INVALID_ASSIGNMENT, 254, 3),
-      error(WarningCode.UNNECESSARY_CAST, 268, 13),
-      error(WarningCode.UNNECESSARY_CAST, 292, 15),
       error(HintCode.UNUSED_LOCAL_VARIABLE, 328, 1),
       error(CompileTimeErrorCode.INVALID_ASSIGNMENT, 340, 7),
       error(CompileTimeErrorCode.INVALID_ASSIGNMENT, 376, 3),
-      error(WarningCode.UNNECESSARY_CAST, 404, 13),
-      error(WarningCode.UNNECESSARY_CAST, 428, 15),
       error(HintCode.UNUSED_LOCAL_VARIABLE, 462, 1),
       error(CompileTimeErrorCode.INVALID_ASSIGNMENT, 492, 7),
       error(CompileTimeErrorCode.INVALID_ASSIGNMENT, 510, 3),
       error(CompileTimeErrorCode.INVALID_ASSIGNMENT, 524, 3),
-      error(WarningCode.UNNECESSARY_CAST, 538, 13),
-      error(WarningCode.UNNECESSARY_CAST, 562, 15),
       error(CompileTimeErrorCode.INVALID_ASSIGNMENT, 562, 15),
       error(HintCode.UNUSED_LOCAL_VARIABLE, 596, 1),
       error(CompileTimeErrorCode.INVALID_ASSIGNMENT, 608, 7),
       error(CompileTimeErrorCode.INVALID_ASSIGNMENT, 644, 3),
       error(CompileTimeErrorCode.INVALID_ASSIGNMENT, 658, 3),
-      error(WarningCode.UNNECESSARY_CAST, 672, 13),
       error(CompileTimeErrorCode.INVALID_ASSIGNMENT, 696, 15),
-      error(WarningCode.UNNECESSARY_CAST, 696, 15),
       error(HintCode.UNUSED_LOCAL_VARIABLE, 737, 1),
-      error(WarningCode.UNNECESSARY_CAST, 813, 13),
-      error(WarningCode.UNNECESSARY_CAST, 837, 15),
     ]);
   }
 
@@ -2054,9 +2040,7 @@ void main() {
       error(HintCode.UNUSED_LOCAL_VARIABLE, 365, 1),
       error(HintCode.UNUSED_LOCAL_VARIABLE, 665, 1),
       error(WarningCode.UNNECESSARY_CAST, 674, 10),
-      error(WarningCode.UNNECESSARY_CAST, 710, 10),
       error(WarningCode.UNNECESSARY_CAST, 747, 11),
-      error(WarningCode.UNNECESSARY_CAST, 804, 11),
     ]);
   }
 

diff --git a/pkg/analyzer/test/src/task/strong/inferred_type_test.dart b/pkg/analyzer/test/src/task/strong/inferred_type_test.dart
@@ -2547,7 +2547,6 @@ $declared foo() => new $declared<int>.value(1);
         error(HintCode.UNUSED_LOCAL_VARIABLE, 309, 2),
         error(CompileTimeErrorCode.INVALID_ASSIGNMENT, 314, 1),
         error(HintCode.UNUSED_LOCAL_VARIABLE, 475, 2),
-        error(WarningCode.UNNECESSARY_CAST, 480, 47),
       ],
     );
     await disposeAnalysisContextCollection();
@@ -3068,7 +3067,6 @@ main() {
           contextMessages: [message('/home/test/lib/test.dart', 12, 1)]),
       error(CompileTimeErrorCode.INVALID_OVERRIDE, 94, 1,
           contextMessages: [message('/home/test/lib/test.dart', 33, 1)]),
-      error(WarningCode.UNNECESSARY_CAST, 132, 12),
     ]);
   }
 
@@ -3601,12 +3599,8 @@ test1() {
       error(CompileTimeErrorCode.UNDEFINED_IDENTIFIER, 171, 1),
       error(CompileTimeErrorCode.UNDEFINED_IDENTIFIER, 201, 1),
       error(CompileTimeErrorCode.UNDEFINED_OPERATOR, 572, 1),
-      error(
-          isNullSafetyEnabled
-              ? WarningCode.CAST_FROM_NULL_ALWAYS_FAILS
-              : WarningCode.UNNECESSARY_CAST,
-          591,
-          9),
+      if (isNullSafetyEnabled)
+        error(WarningCode.CAST_FROM_NULL_ALWAYS_FAILS, 591, 9),
       error(CompileTimeErrorCode.INVALID_ASSIGNMENT, 619, 4),
       error(CompileTimeErrorCode.INVALID_ASSIGNMENT, 647, 4),
       error(CompileTimeErrorCode.INVALID_ASSIGNMENT, 687, 2),