[analyzer] Revert 'Fix broken code generators in g3.' and add new fix for code generators that result in InvalidTypes.

Reverting previous change since it does break some other parts of g3. Shortcircuiting the `??` isn't sufficient in some cases. So we attempt to fix it further downstream.

This change does a check for unresolved types and ignores the cast since we can't tell what type it is anyways. Similar to what we do with type parameters and when we don't know the type.

The generators in g3 seem to emit a lot more InvalidTypes and this is necessary to avoid the errors now that we propagate errors upwards.

b/293326927

Change-Id: I172980dfd3338f27d0a57e156b15dd937619ff73
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/316841
Commit-Queue: Kallen Tu <[email protected]>
Reviewed-by: Samuel Rawlins <[email protected]>

Author: kallentu

pkg/analyzer/lib/src/dart/constant/evaluation.dart

@@ -2026,11 +2026,6 @@ class DartObjectComputer {
   Constant lazyQuestionQuestion(Expression node, DartObjectImpl leftOperand,
       Constant Function() rightOperandComputer) {
     if (leftOperand.isNull) {
-      // TODO(kallentu): Remove this once we have a better representation for
-      // unresolved types.
-      if (leftOperand.isInvalid) {
-        return leftOperand;
-      }
       return rightOperandComputer();
     }
     return leftOperand;

pkg/analyzer/lib/src/dart/constant/has_invalid_type.dart

@@ -0,0 +1,34 @@
+// Copyright (c) 2023, 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/dart/element/type.dart';
+import 'package:analyzer/src/dart/element/type_visitor.dart';
+
+/// Return `true` if the [type] has an [InvalidType].
+bool hasInvalidType(DartType type) {
+  var visitor = _InvalidTypeVisitor();
+  type.accept(visitor);
+  return visitor.result;
+}
+
+/// A visitor to find if a type contains any [InvalidType]s.
+///
+/// To find the result, check [result] on this instance after visiting the tree.
+///
+/// The actual value returned by the visit methods is merely used so that
+/// [RecursiveTypeVisitor] stops visiting the type once the first type parameter
+/// type is found.
+class _InvalidTypeVisitor extends RecursiveTypeVisitor {
+  /// The result of whether any [InvalidType]s were found.
+  bool result = false;
+
+  @override
+  bool visitDartType(DartType dartType) {
+    if (dartType is InvalidType) {
+      result = true;
+      return false;
+    }
+    return true;
+  }
+}

pkg/analyzer/lib/src/dart/constant/value.dart

@@ -15,6 +15,7 @@ import 'package:analyzer/dart/element/type.dart';
 import 'package:analyzer/dart/element/type_provider.dart';
 import 'package:analyzer/diagnostic/diagnostic.dart';
 import 'package:analyzer/error/error.dart';
+import 'package:analyzer/src/dart/constant/has_invalid_type.dart';
 import 'package:analyzer/src/dart/constant/has_type_parameter_reference.dart';
 import 'package:analyzer/src/dart/element/element.dart';
 import 'package:analyzer/src/dart/element/extensions.dart';
@@ -306,6 +307,14 @@ class DartObjectImpl implements DartObject, Constant {
       return this;
     }
 
+    // If any type is unresolved, we cannot prove that the cast will fail.
+    if (isInvalid ||
+        castType.isInvalid ||
+        hasInvalidType(type) ||
+        hasInvalidType(resultType)) {
+      return this;
+    }
+
     // We don't know the actual value of a type parameter.
     // So, the object type might be a subtype of the result type.
     if (hasTypeParameterReference(resultType)) {