diff --git a/pkg/front_end/lib/src/testing/id.dart b/pkg/front_end/lib/src/testing/id.dart
index 49079470a9cc..f0b323e7d8c0 100644
--- a/pkg/front_end/lib/src/testing/id.dart
+++ b/pkg/front_end/lib/src/testing/id.dart
@@ -34,6 +34,9 @@ enum IdKind {
   /// certain offset. This is used in [NodeId].
   moveNext,
 
+  /// Id used for the implicit as expression inserted by the compiler.
+  implicitAs,
+
   /// Id used for the statement at certain offset. This is used in [NodeId].
   stmt,
 
@@ -96,6 +99,8 @@ class IdValue {
         return '$currentPrefix$value';
       case IdKind.moveNext:
         return '$moveNextPrefix$value';
+      case IdKind.implicitAs:
+        return '$implicitAsPrefix$value';
       case IdKind.stmt:
         return '$stmtPrefix$value';
       case IdKind.error:
@@ -113,6 +118,7 @@ class IdValue {
   static const String iteratorPrefix = "iterator: ";
   static const String currentPrefix = "current: ";
   static const String moveNextPrefix = "moveNext: ";
+  static const String implicitAsPrefix = "as: ";
   static const String stmtPrefix = "stmt: ";
   static const String errorPrefix = "error: ";
 
@@ -159,6 +165,9 @@ class IdValue {
     } else if (text.startsWith(moveNextPrefix)) {
       id = new NodeId(offset, IdKind.moveNext);
       expected = text.substring(moveNextPrefix.length);
+    } else if (text.startsWith(implicitAsPrefix)) {
+      id = new NodeId(offset, IdKind.implicitAs);
+      expected = text.substring(implicitAsPrefix.length);
     } else if (text.startsWith(stmtPrefix)) {
       id = new NodeId(offset, IdKind.stmt);
       expected = text.substring(stmtPrefix.length);
@@ -340,17 +349,19 @@ abstract class DataRegistry<T> {
   ///
   /// Checks for duplicate data for [id].
   void registerValue(Uri uri, int offset, Id id, T value, Object object) {
-    if (actualMap.containsKey(id)) {
-      ActualData<T> existingData = actualMap[id];
-      report(uri, offset, "Duplicate id ${id}, value=$value, object=$object");
-      report(
-          uri,
-          offset,
-          "Duplicate id ${id}, value=${existingData.value}, "
-          "object=${existingData.object}");
-      fail("Duplicate id $id.");
-    }
     if (value != null) {
+      if (actualMap.containsKey(id)) {
+        // TODO(johnniwinther): Maybe let the test supply a way to merge
+        // multiple data on the same id?
+        ActualData<T> existingData = actualMap[id];
+        report(uri, offset, "Duplicate id ${id}, value=$value, object=$object");
+        report(
+            uri,
+            offset,
+            "Duplicate id ${id}, value=${existingData.value}, "
+            "object=${existingData.object}");
+        fail("Duplicate id $id.");
+      }
       actualMap[id] = new ActualData<T>(id, value, uri, offset, object);
     }
   }
diff --git a/pkg/front_end/lib/src/testing/id_extractor.dart b/pkg/front_end/lib/src/testing/id_extractor.dart
index 88ee421f0380..9ea0e06896fa 100644
--- a/pkg/front_end/lib/src/testing/id_extractor.dart
+++ b/pkg/front_end/lib/src/testing/id_extractor.dart
@@ -136,6 +136,14 @@ abstract class DataExtractor<T> extends Visitor with DataRegistry<T> {
   NodeId createSwitchCaseId(SwitchCase node) =>
       new NodeId(node.expressionOffsets.first, IdKind.node);
 
+  NodeId createImplicitAsId(AsExpression node) {
+    if (node.fileOffset == TreeNode.noOffset) {
+      // TODO(johnniwinther): Find out why we something have no offset.
+      return null;
+    }
+    return new NodeId(node.fileOffset, IdKind.implicitAs);
+  }
+
   void run(Node root) {
     root.accept(this);
   }
@@ -376,4 +384,55 @@ abstract class DataExtractor<T> extends Visitor with DataRegistry<T> {
     }
     super.visitThisExpression(node);
   }
+
+  @override
+  visitAwaitExpression(AwaitExpression node) {
+    computeForNode(node, computeDefaultNodeId(node));
+    super.visitAwaitExpression(node);
+  }
+
+  @override
+  visitConstructorInvocation(ConstructorInvocation node) {
+    // Skip synthetic constructor invocations like for enum constants.
+    // TODO(johnniwinther): Can [skipNodeWithNoOffset] be removed when dart2js
+    // no longer test with cfe constants?
+    computeForNode(
+        node, computeDefaultNodeId(node, skipNodeWithNoOffset: true));
+    super.visitConstructorInvocation(node);
+  }
+
+  @override
+  visitStaticGet(StaticGet node) {
+    computeForNode(node, computeDefaultNodeId(node));
+    super.visitStaticGet(node);
+  }
+
+  @override
+  visitStaticSet(StaticSet node) {
+    computeForNode(node, createUpdateId(node));
+    super.visitStaticSet(node);
+  }
+
+  @override
+  visitStaticInvocation(StaticInvocation node) {
+    computeForNode(node, createInvokeId(node));
+    super.visitStaticInvocation(node);
+  }
+
+  @override
+  visitAsExpression(AsExpression node) {
+    if (node.isTypeError) {
+      computeForNode(node, createImplicitAsId(node));
+    } else {
+      computeForNode(node, computeDefaultNodeId(node));
+    }
+    return super.visitAsExpression(node);
+  }
+
+  @override
+  visitArguments(Arguments node) {
+    computeForNode(
+        node, computeDefaultNodeId(node, skipNodeWithNoOffset: true));
+    return super.visitArguments(node);
+  }
 }
diff --git a/pkg/front_end/test/static_types/data/issue37439.dart b/pkg/front_end/test/static_types/data/issue37439.dart
new file mode 100644
index 000000000000..253ac53c40c7
--- /dev/null
+++ b/pkg/front_end/test/static_types/data/issue37439.dart
@@ -0,0 +1,18 @@
+// Copyright (c) 2019, 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.
+
+class A {}
+
+class B extends A {}
+
+Future<T> func1<T extends A>(T t) async {
+  // TODO(37439): We should infer 'T' instead of '<bottom>'.
+  return /*invoke: <bottom>*/ func2/*<<bottom>>*/(/*as: <bottom>*/ /*T*/ t);
+}
+
+T func2<T extends A>(T t) => /*T*/ t;
+
+main() async {
+  /*B*/ await /*invoke: Future<B>*/ func1/*<B>*/(/*B*/ B());
+}
diff --git a/pkg/front_end/test/static_types/static_type_test.dart b/pkg/front_end/test/static_types/static_type_test.dart
index d91866a2a6da..608d9485314f 100644
--- a/pkg/front_end/test/static_types/static_type_test.dart
+++ b/pkg/front_end/test/static_types/static_type_test.dart
@@ -51,6 +51,10 @@ class StaticTypeDataExtractor extends CfeDataExtractor<String> {
     if (node is Expression) {
       DartType type = node.getStaticType(_environment);
       return typeToText(type);
+    } else if (node is Arguments) {
+      if (node.types.isNotEmpty) {
+        return '<${node.types.map(typeToText).join(',')}>';
+      }
     }
     return null;
   }