Move checkIndexExpressionIndex checking to resolver.

In order to implement "why not promoted" functionality index
expressions, we need to call checkIndexExpressionIndex from the
resolver, so that we can pass it failed promotion information.  So
move it into the ErrorDetectionHelpers mixin.

Bug: #44898
Change-Id: Idc70e3421142da1d3100c288c912b6483a91b28c
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/193087
Reviewed-by: Konstantin Shcheglov <[email protected]>

Author: stereotype441

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

@@ -55,32 +55,14 @@ mixin ErrorDetectionHelpers {
   void checkForArgumentTypeNotAssignableForArgument(Expression argument,
       {bool promoteParameterToNullable = false,
       Map<DartType, NonPromotionReason> Function()? whyNotPromoted}) {
-    checkForArgumentTypeNotAssignableForArgument2(
+    _checkForArgumentTypeNotAssignableForArgument2(
       argument: argument,
       parameter: argument.staticParameterElement,
       promoteParameterToNullable: promoteParameterToNullable,
       whyNotPromoted: whyNotPromoted,
     );
   }
 
-  void checkForArgumentTypeNotAssignableForArgument2({
-    required Expression argument,
-    required ParameterElement? parameter,
-    required bool promoteParameterToNullable,
-    Map<DartType, NonPromotionReason> Function()? whyNotPromoted,
-  }) {
-    var staticParameterType = parameter?.type;
-    if (promoteParameterToNullable && staticParameterType != null) {
-      staticParameterType =
-          typeSystem.makeNullable(staticParameterType as TypeImpl);
-    }
-    _checkForArgumentTypeNotAssignableWithExpectedTypes(
-        argument,
-        staticParameterType,
-        CompileTimeErrorCode.ARGUMENT_TYPE_NOT_ASSIGNABLE,
-        whyNotPromoted);
-  }
-
   /// Verify that the given constructor field [initializer] has compatible field
   /// and initializer expression types. The [fieldElement] is the static element
   /// from the name in the [ConstructorFieldInitializer].
@@ -205,6 +187,34 @@ mixin ErrorDetectionHelpers {
     return true;
   }
 
+  void checkIndexExpressionIndex(
+    Expression index, {
+    required ExecutableElement? readElement,
+    required ExecutableElement? writeElement,
+  }) {
+    if (readElement is MethodElement) {
+      var parameters = readElement.parameters;
+      if (parameters.isNotEmpty) {
+        _checkForArgumentTypeNotAssignableForArgument2(
+          argument: index,
+          parameter: parameters[0],
+          promoteParameterToNullable: false,
+        );
+      }
+    }
+
+    if (writeElement is MethodElement) {
+      var parameters = writeElement.parameters;
+      if (parameters.isNotEmpty) {
+        _checkForArgumentTypeNotAssignableForArgument2(
+          argument: index,
+          parameter: parameters[0],
+          promoteParameterToNullable: false,
+        );
+      }
+    }
+  }
+
   /// Computes the appropriate set of context messages to report along with an
   /// error that may have occurred because [expression] was not type promoted.
   ///
@@ -233,6 +243,24 @@ mixin ErrorDetectionHelpers {
     return null;
   }
 
+  void _checkForArgumentTypeNotAssignableForArgument2({
+    required Expression argument,
+    required ParameterElement? parameter,
+    required bool promoteParameterToNullable,
+    Map<DartType, NonPromotionReason> Function()? whyNotPromoted,
+  }) {
+    var staticParameterType = parameter?.type;
+    if (promoteParameterToNullable && staticParameterType != null) {
+      staticParameterType =
+          typeSystem.makeNullable(staticParameterType as TypeImpl);
+    }
+    _checkForArgumentTypeNotAssignableWithExpectedTypes(
+        argument,
+        staticParameterType,
+        CompileTimeErrorCode.ARGUMENT_TYPE_NOT_ASSIGNABLE,
+        whyNotPromoted);
+  }
+
   /// Verify that the given [expression] can be assigned to its corresponding
   /// parameters.
   ///

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

@@ -349,13 +349,6 @@ class ErrorVerifier extends RecursiveAstVisitor<void>
       _checkForDeadNullCoalesce(node.readType as TypeImpl, node.rightHandSide);
     }
     _checkForAssignmentToFinal(lhs);
-    if (lhs is IndexExpression) {
-      _checkIndexExpressionIndex(
-        lhs.index,
-        readElement: node.readElement as ExecutableElement?,
-        writeElement: node.writeElement as ExecutableElement?,
-      );
-    }
     super.visitAssignmentExpression(node);
   }
 
@@ -830,12 +823,6 @@ class ErrorVerifier extends RecursiveAstVisitor<void>
 
   @override
   void visitIndexExpression(IndexExpression node) {
-    _checkIndexExpressionIndex(
-      node.index,
-      readElement: node.staticElement,
-      writeElement: null,
-    );
-
     if (node.isNullAware) {
       _checkForUnnecessaryNullAware(
         node.realTarget,
@@ -1006,13 +993,6 @@ class ErrorVerifier extends RecursiveAstVisitor<void>
       _checkForAssignmentToFinal(operand);
       _checkForIntNotAssignable(operand);
     }
-    if (operand is IndexExpression) {
-      _checkIndexExpressionIndex(
-        operand.index,
-        readElement: node.readElement as ExecutableElement?,
-        writeElement: node.writeElement as ExecutableElement?,
-      );
-    }
     super.visitPostfixExpression(node);
   }
 
@@ -1038,13 +1018,6 @@ class ErrorVerifier extends RecursiveAstVisitor<void>
       checkForUseOfVoidResult(operand);
       _checkForIntNotAssignable(operand);
     }
-    if (operand is IndexExpression) {
-      _checkIndexExpressionIndex(
-        operand.index,
-        readElement: node.readElement as ExecutableElement?,
-        writeElement: node.writeElement as ExecutableElement?,
-      );
-    }
     super.visitPrefixExpression(node);
   }
 
@@ -4594,34 +4567,6 @@ class ErrorVerifier extends RecursiveAstVisitor<void>
     }
   }
 
-  void _checkIndexExpressionIndex(
-    Expression index, {
-    required ExecutableElement? readElement,
-    required ExecutableElement? writeElement,
-  }) {
-    if (readElement is MethodElement) {
-      var parameters = readElement.parameters;
-      if (parameters.isNotEmpty) {
-        checkForArgumentTypeNotAssignableForArgument2(
-          argument: index,
-          parameter: parameters[0],
-          promoteParameterToNullable: false,
-        );
-      }
-    }
-
-    if (writeElement is MethodElement) {
-      var parameters = writeElement.parameters;
-      if (parameters.isNotEmpty) {
-        checkForArgumentTypeNotAssignableForArgument2(
-          argument: index,
-          parameter: parameters[0],
-          promoteParameterToNullable: false,
-        );
-      }
-    }
-  }
-
   void _checkMixinInference(
       NamedCompilationUnitMember node, WithClause? withClause) {
     if (withClause == null) {

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

@@ -709,6 +709,11 @@ class ResolverVisitor extends ScopedVisitor with ErrorDetectionHelpers {
 
       InferenceContext.setType(node.index, result.indexContextType);
       node.index.accept(this);
+      checkIndexExpressionIndex(
+        node.index,
+        readElement: result.readElement as ExecutableElement?,
+        writeElement: result.writeElement as ExecutableElement?,
+      );
 
       return result;
     } else if (node is PrefixedIdentifier) {
@@ -1702,6 +1707,11 @@ class ResolverVisitor extends ScopedVisitor with ErrorDetectionHelpers {
 
     InferenceContext.setType(node.index, result.indexContextType);
     node.index.accept(this);
+    checkIndexExpressionIndex(
+      node.index,
+      readElement: result.readElement as ExecutableElement?,
+      writeElement: null,
+    );
 
     DartType type;
     if (identical(node.realTarget.staticType, NeverTypeImpl.instance)) {

pkg/analyzer/lib/src/test_utilities/mock_sdk.dart

@@ -459,7 +459,7 @@ abstract class Map<K, V> {
   int get length => 0;
   Iterable<V> get values;
 
-  V? operator [](K key);
+  V? operator [](Object? key);
   void operator []=(K key, V value);
 
   Map<RK, RV> cast<RK, RV>();

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

@@ -454,6 +454,40 @@ f(A a) {
     ]);
   }
 
+  test_map_indexGet() async {
+    // Any type may be passed to Map.operator[].
+    await assertNoErrorsInCode('''
+main() {
+  Map<int, int> m = <int, int>{};
+  m['x'];
+}
+''');
+  }
+
+  test_map_indexSet() async {
+    // The type passed to Map.operator[]= must match the key type.
+    await assertErrorsInCode('''
+main() {
+  Map<int, int> m = <int, int>{};
+  m['x'] = 0;
+}
+''', [
+      error(CompileTimeErrorCode.ARGUMENT_TYPE_NOT_ASSIGNABLE, 47, 3),
+    ]);
+  }
+
+  test_map_indexSet_ifNull() async {
+    // The type passed to Map.operator[]= must match the key type.
+    await assertErrorsInCode('''
+main() {
+  Map<int, int> m = <int, int>{};
+  m['x'] ??= 0;
+}
+''', [
+      error(CompileTimeErrorCode.ARGUMENT_TYPE_NOT_ASSIGNABLE, 47, 3),
+    ]);
+  }
+
   test_new_generic() async {
     await assertErrorsInCode('''
 class A<T> {