analyzer: Resolve extension methods on nullable Never type

Fixes https://github.com/dart-lang/sdk/issues/55000

Cq-Include-Trybots: luci.dart.try:flutter-analyze-try,analyzer-win-release-try,pkg-win-release-try
Change-Id: Ie71d4762bc294028787c28976b2e0a7e604ab2fa
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/372880
Reviewed-by: Konstantin Shcheglov <scheglov@google.com>
Commit-Queue: Sam Rawlins <srawlins@google.com>

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

@@ -71,6 +71,10 @@ class MethodInvocationResolver with ScopeHelpers {
 
   TypeSystemImpl get _typeSystem => _resolver.typeSystem;
 
+  /// Resolves the method invocation, [node].
+  ///
+  /// If [node] is rewritten to be a [FunctionExpressionInvocation] in the
+  /// process, then returns that new node. Otherwise, returns `null`.
   FunctionExpressionInvocation? resolve(
       MethodInvocationImpl node, List<WhyNotPromotedGetter> whyNotPromotedList,
       {required DartType contextType}) {
@@ -142,9 +146,9 @@ class MethodInvocationResolver with ScopeHelpers {
     }
 
     if (receiverType is NeverTypeImpl) {
-      _resolveReceiverNever(node, receiver, receiverType, whyNotPromotedList,
+      return _resolveReceiverNever(
-          contextType: contextType);
+          node, receiver, receiverType, whyNotPromotedList,
-      return null;
+          contextType: contextType, nameNode: nameNode, name: name);
     }
 
     if (receiverType is VoidType) {
@@ -344,6 +348,10 @@ class MethodInvocationResolver with ScopeHelpers {
     return null;
   }
 
+  /// Resolves the method invocation, [node], as an extension member.
+  ///
+  /// If [node] is rewritten to be a [FunctionExpressionInvocation] in the
+  /// process, then returns that new node. Otherwise, returns `null`.
   FunctionExpressionInvocation? _resolveExtensionMember(
       MethodInvocationImpl node,
       Identifier receiver,
@@ -380,6 +388,11 @@ class MethodInvocationResolver with ScopeHelpers {
     return null;
   }
 
+  /// Resolves the method invocation, [node], as called on an extension
+  /// override.
+  ///
+  /// If [node] is rewritten to be a [FunctionExpressionInvocation] in the
+  /// process, then returns that new node. Otherwise, returns `null`.
   FunctionExpressionInvocation? _resolveExtensionOverride(
       MethodInvocationImpl node,
       ExtensionOverride override,
@@ -468,9 +481,20 @@ class MethodInvocationResolver with ScopeHelpers {
         .resolveInvocation(rawType: rawType);
   }
 
-  void _resolveReceiverNever(MethodInvocationImpl node, Expression receiver,
+  /// Resolves the method invocation, [node], as an instance invocation on an
-      DartType receiverType, List<WhyNotPromotedGetter> whyNotPromotedList,
+  /// expression of type `Never` or `Never?`.
-      {required DartType contextType}) {
+  ///
+  /// If [node] is rewritten to be a [FunctionExpressionInvocation] in the
+  /// process, then returns that new node. Otherwise, returns `null`.
+  FunctionExpressionInvocation? _resolveReceiverNever(
+    MethodInvocationImpl node,
+    Expression receiver,
+    DartType receiverType,
+    List<WhyNotPromotedGetter> whyNotPromotedList, {
+    required DartType contextType,
+    required SimpleIdentifierImpl nameNode,
+    required String name,
+  }) {
     _setExplicitTypeArgumentTypes();
 
     if (receiverType == NeverTypeImpl.instanceNullable) {
@@ -485,16 +509,19 @@ class MethodInvocationResolver with ScopeHelpers {
           whyNotPromotedList,
           contextType: contextType,
         );
+        return null;
       } else {
-        _setInvalidTypeResolution(node,
+        return _resolveReceiverType(
-            whyNotPromotedList: whyNotPromotedList, contextType: contextType);
+          node: node,
-        _resolver.nullableDereferenceVerifier.report(
+          receiver: receiver,
-          CompileTimeErrorCode.UNCHECKED_METHOD_INVOCATION_OF_NULLABLE_VALUE,
+          receiverType: receiverType,
-          methodName,
+          nameNode: nameNode,
-          receiverType,
+          name: name,
+          receiverErrorNode: receiver,
+          whyNotPromotedList: whyNotPromotedList,
+          contextType: contextType,
         );
       }
-      return;
     }
 
     if (receiverType == NeverTypeImpl.instance) {
@@ -514,10 +541,16 @@ class MethodInvocationResolver with ScopeHelpers {
       node.methodName.setPseudoExpressionStaticType(_dynamicType);
       node.staticInvokeType = _dynamicType;
       node.recordStaticType(NeverTypeImpl.instance, resolver: _resolver);
-      return;
+      return null;
     }
+    return null;
   }
 
+  /// Resolves the method invocation, [node], as an instance invocation on an
+  /// expression of type `Null`.
+  ///
+  /// If [node] is rewritten to be a [FunctionExpressionInvocation] in the
+  /// process, then returns that new node. Otherwise, returns `null`.
   FunctionExpressionInvocation? _resolveReceiverNull(
       MethodInvocationImpl node,
       SimpleIdentifierImpl nameNode,
@@ -620,6 +653,11 @@ class MethodInvocationResolver with ScopeHelpers {
     );
   }
 
+  /// Resolves the method invocation, [node], as a top-level function
+  /// invocation, referenced with a prefix.
+  ///
+  /// If [node] is rewritten to be a [FunctionExpressionInvocation] in the
+  /// process, then returns that new node. Otherwise, returns `null`.
   FunctionExpressionInvocation? _resolveReceiverPrefix(
       MethodInvocationImpl node,
       PrefixElement prefix,
@@ -679,6 +717,11 @@ class MethodInvocationResolver with ScopeHelpers {
     return null;
   }
 
+  /// Resolves the method invocation, [node], as an instance invocation a
+  /// `super` expression.
+  ///
+  /// If [node] is rewritten to be a [FunctionExpressionInvocation] in the
+  /// process, then returns that new node. Otherwise, returns `null`.
   FunctionExpressionInvocation? _resolveReceiverSuper(
       MethodInvocationImpl node,
       SuperExpression receiver,
@@ -740,6 +783,10 @@ class MethodInvocationResolver with ScopeHelpers {
     return null;
   }
 
+  /// Resolves the type of the receiver of the method invocation, [node].
+  ///
+  /// If [node] is rewritten to be a [FunctionExpressionInvocation] in the
+  /// process, then returns that new node. Otherwise, returns `null`.
   FunctionExpressionInvocation? _resolveReceiverType({
     required MethodInvocationImpl node,
     required Expression? receiver,
@@ -830,6 +877,11 @@ class MethodInvocationResolver with ScopeHelpers {
     return null;
   }
 
+  /// Resolves the method invocation, [node], as an method invocation with a
+  /// type literal target.
+  ///
+  /// If [node] is rewritten to be a [FunctionExpressionInvocation] in the
+  /// process, then returns that new node. Otherwise, returns `null`.
   FunctionExpressionInvocation? _resolveReceiverTypeLiteral(
       MethodInvocationImpl node,
       InterfaceElement receiver,
@@ -882,12 +934,14 @@ class MethodInvocationResolver with ScopeHelpers {
     return null;
   }
 
+  /// Rewrites [node] as a [FunctionExpressionInvocation].
+  ///
   /// We have identified that [node] is not a real [MethodInvocation],
   /// because it does not invoke a method, but instead invokes the result
   /// of a getter execution, or implicitly invokes the `call` method of
   /// an [InterfaceType]. So, it should be represented as instead as a
   /// [FunctionExpressionInvocation].
-  FunctionExpressionInvocation? _rewriteAsFunctionExpressionInvocation(
+  FunctionExpressionInvocation _rewriteAsFunctionExpressionInvocation(
       MethodInvocationImpl node, DartType getterReturnType,
       {bool isSuperAccess = false}) {
     var targetType = _typeSystem.resolveToBound(getterReturnType);

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

@@ -267,6 +267,10 @@ class ElementResolver {
     _resolveAnnotations(node.metadata);
   }
 
+  /// Resolves the method invocation, [node].
+  ///
+  /// If [node] is rewritten to be a [FunctionExpressionInvocation] in the
+  /// process, then returns that new node. Otherwise, returns `null`.
   FunctionExpressionInvocation? visitMethodInvocation(MethodInvocation node,
       {List<WhyNotPromotedGetter>? whyNotPromotedList,
       required DartType contextType}) {

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

@@ -216,6 +216,18 @@ extension E on A? {
     ]);
   }
 
+  test_methodInvocation_nuverNullable_extensionMethod() async {
+    await assertNoErrorsInCode(r'''
+extension<X> on X {
+  X m() => this;
+}
+
+Future<void> f(Never? x) async {
+  (await x).m();
+}
+''');
+  }
+
   test_prefixExpression_minus_nonNullable() async {
     await assertNoErrorsInCode(r'''
 class A {