Consider '[]' and '[]=' as having the same base name '[]' for extensi…

…ons.

Update ResolutionResult to be just getter and setter.
No properties, no functions.

Bug: #38484
Change-Id: If2b50e30eb98eb280142bbe12e4f0c31041ef652
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/118342
Reviewed-by: Mike Fairhurst <mfairhurst@google.com>
Commit-Queue: Konstantin Shcheglov <scheglov@google.com>

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

@@ -291,17 +291,38 @@ class ExtensionMemberResolver {
       for (var field in extension.fields) {
         if (field.name == name) {
           candidates.add(
-            _CandidateExtension(extension, field: field),
+            _CandidateExtension(
+              extension,
+              getter: field.getter,
+              setter: field.setter,
+            ),
           );
           return;
         }
       }
-      for (var method in extension.methods) {
-        if (method.name == name) {
+      if (name == '[]') {
+        ExecutableElement getter;
+        ExecutableElement setter;
+        for (var method in extension.methods) {
+          if (method.name == '[]') {
+            getter = method;
+          } else if (method.name == '[]=') {
+            setter = method;
+          }
+        }
+        if (getter != null || setter != null) {
           candidates.add(
-            _CandidateExtension(extension, method: method),
+            _CandidateExtension(extension, getter: getter, setter: setter),
           );
-          return;
+        }
+      } else {
+        for (var method in extension.methods) {
+          if (method.name == name) {
+            candidates.add(
+              _CandidateExtension(extension, getter: method),
+            );
+            return;
+          }
         }
       }
     }
@@ -429,11 +450,11 @@ class ExtensionMemberResolver {
 
 class _CandidateExtension {
   final ExtensionElement extension;
-  final FieldElement field;
-  final MethodElement method;
+  final ExecutableElement getter;
+  final ExecutableElement setter;
 
-  _CandidateExtension(this.extension, {this.field, this.method})
-      : assert(field != null || method != null);
+  _CandidateExtension(this.extension, {this.getter, this.setter})
+      : assert(getter != null || setter != null);
 }
 
 class _InstantiatedExtension {
@@ -444,22 +465,22 @@ class _InstantiatedExtension {
   _InstantiatedExtension(this.candidate, this.substitution, this.extendedType);
 
   ResolutionResult get asResolutionResult {
-    return ResolutionResult(function: method, property: field);
+    return ResolutionResult(getter: getter, setter: setter);
   }
 
   ExtensionElement get extension => candidate.extension;
 
-  FieldElement get field {
-    if (candidate.field == null) {
+  ExecutableElement get getter {
+    if (candidate.getter == null) {
       return null;
     }
-    return FieldMember.from2(candidate.field, substitution);
+    return ExecutableMember.from2(candidate.getter, substitution);
   }
 
-  MethodElement get method {
-    if (candidate.method == null) {
+  ExecutableElement get setter {
+    if (candidate.setter == null) {
       return null;
     }
-    return MethodMember.from2(candidate.method, substitution);
+    return ExecutableMember.from2(candidate.setter, substitution);
   }
 }

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

@@ -747,7 +747,7 @@ class MethodInvocationResolver {
         var result = _extensionResolver.findExtension(
             type, _nameCall.name, node.methodName);
         if (result.isSingle) {
-          call = result.function;
+          call = result.getter;
         } else if (result.isAmbiguous) {
           return;
         }

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

@@ -4,7 +4,7 @@
 
 import 'package:analyzer/dart/element/element.dart';
 
-/// The result of attempting to resolve an identifier to a element.
+/// The result of attempting to resolve an identifier to elements.
 class ResolutionResult {
   /// An instance that can be used anywhere that no element was found.
   static const ResolutionResult none =
@@ -17,27 +17,22 @@ class ResolutionResult {
   /// The state of the result.
   final _ResolutionResultState state;
 
-  /// The function that was found, or `null` if the [state] is not
-  /// [_ResolutionResultState.single], or a [property] was found.
-  final ExecutableElement function;
+  /// Return the element that is invoked for reading.
+  final ExecutableElement getter;
 
-  /// The property that was found, or `null` if the [state] is not
-  /// [_ResolutionResultState.single], or a [function] was found.
-  final PropertyInducingElement property;
+  /// Return the element that is invoked for writing.
+  final ExecutableElement setter;
 
-  /// Initialize a newly created result to represent resolving to a single
-  /// [function] or [property].
-  ResolutionResult({this.function, this.property})
-      : assert(function != null || property != null),
+  /// Initialize a newly created result to represent resolving a single
+  /// reading and / or writing result.
+  ResolutionResult({this.getter, this.setter})
+      : assert(getter != null || setter != null),
         state = _ResolutionResultState.single;
 
-  /// Initialize a newly created result with no element and the given [state].
+  /// Initialize a newly created result with no elements and the given [state].
   const ResolutionResult._(this.state)
-      : function = null,
-        property = null;
-
-  /// Return the getter of the [property], or the [function].
-  ExecutableElement get getter => function ?? property?.getter;
+      : getter = null,
+        setter = null;
 
   /// Return `true` if this result represents the case where multiple ambiguous
   /// elements were found.
@@ -55,12 +50,8 @@ class ResolutionResult {
   /// If this is a function, return `true` is the function is static.
   /// Otherwise return `false`.
   bool get isStatic {
-    return function?.isStatic ?? property?.isStatic ?? false;
+    return getter?.isStatic ?? setter?.isStatic ?? false;
   }
-
-  /// Return the setter of the [property], or `null` if this is not a property,
-  /// or the property does not have a setter.
-  ExecutableElement get setter => property?.setter;
 }
 
 /// The state of a [ResolutionResult].