[stable] Fix Dart2JS type inference for record accesses on invalid indices.

Switches can generate record accesses on receivers that don't support the generated selector. Add an if guarding against this case.

Bug: 52438
Change-Id: I2b715c7a8d83b67a503d56d20b595bd90a81a59b
Cherry-pick: https://dart-review.googlesource.com/c/sdk/+/304380
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/304420
Commit-Queue: Nate Biggs <[email protected]>
Reviewed-by: Sigmund Cherem <[email protected]>

Author: natebiggs

CHANGELOG.md

@@ -1,3 +1,9 @@
+## 3.0.2
+
+This is a patch release that:
+
+- Fixes a dart2js crash when using a switch case expression on a record where the fields don't match the cases. (issue [#52438]).
+
 ## 3.0.1
 
 This is a patch release that:

pkg/compiler/lib/src/inferrer/typemasks/masks.dart

@@ -917,10 +917,15 @@ class CommonMasks with AbstractValueDomain {
 
   @override
   AbstractValue getGetterTypeInRecord(AbstractValue value, String getterName) {
-    final type = value is RecordTypeMask
-        ? value.types[value.shape.indexOfGetterName(getterName)]
-        : null;
-    return type ?? dynamicType;
+    if (value is RecordTypeMask) {
+      final getterIndex = value.shape.indexOfGetterName(getterName);
+      // Generated code can sometimes contain record accesses for invalid
+      // getters.
+      if (getterIndex >= 0) {
+        return value.types[getterIndex];
+      }
+    }
+    return dynamicType;
   }
 
   @override

tests/web/regress/issue/52438_test.dart

@@ -0,0 +1,15 @@
+// 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.
+
+// Switches geenrate record accesses on non-existent fields. These accesses
+// should be guarded by a type check but Dart2JS does not always promote
+// correctly after the type check.
+
+void main() {
+  Object r = (1, 2);
+  switch (r) {
+    case (int _, int _, int c):
+      print('Skip, no match');
+  }
+}