Support for a.b.c.d extract property sequence.

pkg/analyzer/lib/src/summary/link.dart

Index: pkg/analyzer/lib/src/summary/link.dart
diff --git a/pkg/analyzer/lib/src/summary/link.dart b/pkg/analyzer/lib/src/summary/link.dart
index 2972635963e6dd7fceae815f92bfb949e3001a72..d98fa63bb4d1ba09ffca8816b9ad4b077697932d 100644
--- a/pkg/analyzer/lib/src/summary/link.dart
+++ b/pkg/analyzer/lib/src/summary/link.dart
@@ -3124,18 +3124,23 @@ abstract class Node<NodeType> {
 }
 
 /**
- * Element used for references that result from trying to access a nonstatic
+ * Element used for references that result from trying to access a non-static
  * member of an element that is not a container (e.g. accessing the "length"
  * property of a constant).
  */
 class NonstaticMemberElementForLink implements ReferenceableElementForLink {
   /**
+   * The non-static element of this link element.
+   */
+  final Element element;
+
+  /**
    * If the thing from which a member was accessed is a constant, the
    * associated [ConstNode].  Otherwise `null`.
    */
   final ConstVariableNode _constNode;
 
-  NonstaticMemberElementForLink(this._constNode);
+  NonstaticMemberElementForLink(this.element, this._constNode);
 
   @override
   ConstructorElementForLink get asConstructor => null;
@@ -3145,6 +3150,10 @@ class NonstaticMemberElementForLink implements ReferenceableElementForLink {
 
   @override
   DartType get asStaticType {
+    Element element = this.element;
+    if (element is PropertyAccessorElement && element.isGetter) {
+      return element.returnType;
+    }
     // TODO(paulberry): implement.
     return DynamicTypeImpl.instance;
   }
@@ -3161,7 +3170,19 @@ class NonstaticMemberElementForLink implements ReferenceableElementForLink {
       DynamicTypeImpl.instance;
 
   @override
-  ReferenceableElementForLink getContainedName(String name) => this;
+  ReferenceableElementForLink getContainedName(String name) {
+    if (element != null) {
+      DartType type = asStaticType;
+      if (type is InterfaceType) {
+        PropertyAccessorElement getter =
+            type.lookUpGetter(name, element.library);
+        if (getter != null) {
+          return new NonstaticMemberElementForLink(getter, _constNode);
+        }

[Paul Berry, 2016/04/16 14:50:09]

else {
  return new NonStaticMemberElementForLink(null, _constNode);
}

So that we don't allow "trying again" after a failed lookup.  E.g. your code
would allow:

class A {
  B b;
}
class B {
  int c;
}
A a;
var x = a.b.foo.c; // Incorrectly infers type of `int`

[scheglov, 2016/04/17 02:38:26]

Done.

+      }
+    }
+    return this;
+  }
 }
 
 /**
@@ -4134,9 +4155,25 @@ class VariableElementForLink
       DynamicTypeImpl.instance;
 
   ReferenceableElementForLink getContainedName(String name) {
-    return new NonstaticMemberElementForLink(_constNode);
+    Element element = _getContainedElement(name);
+    return new NonstaticMemberElementForLink(element, _constNode);
   }
 
   @override
   noSuchMethod(Invocation invocation) => super.noSuchMethod(invocation);
+
+  /**
+   * Return the contained element with the given [name], or `null` if the lookup
+   * fails.

[Paul Berry, 2016/04/16 14:50:09]

Comment should reflect the fact that we don't do the lookup if we're not in
strong mode (and why)

[scheglov, 2016/04/17 02:38:26]

Done.

+   */
+  Element _getContainedElement(String name) {
+    Linker linker = compilationUnit.library._linker;
+    if (linker.strongMode) {
+      DartType type = asStaticType;
+      if (type is InterfaceType) {
+        return type.lookUpGetter(name, compilationUnit.library);
+      }
+    }
+    return null;
+  }
 }