Issue 29109. Resynthesize PrefixElement(s) to fix constants evaluation.

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

 // Copyright (c) 2015, 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.
 
 library summary_resynthesizer;
 
 import 'dart:collection';
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/standard_ast_factory.dart';
@@ skipping 79 matching lines @@
   TypeProvider get typeProvider => _typeProvider;
 
   @override
   Element getElement(ElementLocation location) {
     List<String> components = location.components;
     String libraryUri = components[0];
     // Resynthesize locally.
     if (components.length == 1) {
       return getLibraryElement(libraryUri);
     } else if (components.length == 2) {
-      Map<String, CompilationUnitElement> libraryMap =
-          _resynthesizedUnits[libraryUri];
-      if (libraryMap == null) {
-        getLibraryElement(libraryUri);
-        libraryMap = _resynthesizedUnits[libraryUri];
+      LibraryElement libraryElement = getLibraryElement(libraryUri);
+      // Try to find the unit element.
+      {
+        Map<String, CompilationUnitElement> libraryMap =
+            _resynthesizedUnits[libraryUri];
         assert(libraryMap != null);
+        String unitUri = components[1];
+        CompilationUnitElement unitElement = libraryMap[unitUri];
+        if (unitElement != null) {
+          return unitElement;
+        }
       }
-      String unitUri = components[1];
-      CompilationUnitElement element = libraryMap[unitUri];
-      if (element == null) {
-        throw new Exception('Unit element not found in summary: $location');
+      // Try to find the prefix element.
+      {
+        String name = components[1];
+        for (PrefixElement prefix in libraryElement.prefixes) {
+          if (prefix.name == name) {
+            return prefix;
+          }
+        }
       }
-      return element;
+      // Fail.
+      throw new Exception('The element not found in summary: $location');
     } else if (components.length == 3 || components.length == 4) {
       String unitUri = components[1];
       // Prepare elements-in-units in the library.
       Map<String, Map<String, Element>> unitsInLibrary =
           _resynthesizedElements[libraryUri];
       if (unitsInLibrary == null) {
         unitsInLibrary = new HashMap<String, Map<String, Element>>();
         _resynthesizedElements[libraryUri] = unitsInLibrary;
       }
       // Prepare elements in the unit.
@@ skipping 1672 matching lines @@
         if (enclosingInfo != null && enclosingInfo.element is ClassElement) {
           String identifier = _getElementIdentifier(name, linkedReference.kind);
           locationComponents =
               enclosingInfo.element.location.components.toList();
           locationComponents.add(identifier);
         } else {
           String identifier = _getElementIdentifier(name, linkedReference.kind);
           locationComponents =
               libraryResynthesizer.getReferencedLocationComponents(
                   linkedReference.dependency, linkedReference.unit, identifier);
+          if (linkedReference.kind == ReferenceKind.prefix) {
+            locationComponents = <String>[
+              locationComponents[0],
+              locationComponents[2]
+            ];
+          }
         }
         if (!_resynthesizerContext.isStrongMode &&
             locationComponents.length == 3 &&
             locationComponents[0] == 'dart:async' &&
             locationComponents[2] == 'FutureOr') {
           type = typeProvider.dynamicType;
           numTypeParameters = 0;
         }
         ElementLocation location =
             new ElementLocationImpl.con3(locationComponents);
@@ skipping 53 matching lines @@
               element = new _DeferredInitializerElement(enclosingElement);
             } else if (enclosingElement is ExecutableElement) {
               element = new _DeferredLocalFunctionElement(
                   enclosingElement, linkedReference.localIndex);
             } else {
               throw new StateError('Unexpected element enclosing function:'
                   ' ${enclosingElement.runtimeType}');
             }
             break;
           case ReferenceKind.prefix:
+            element = new PrefixElementHandle(summaryResynthesizer, location);
+            break;
           case ReferenceKind.unresolved:
             break;
         }
       }
       result = new _ReferenceInfo(libraryResynthesizer, enclosingInfo, name,
           isDeclarableType, element, type, numTypeParameters);
       referenceInfos[index] = result;
     }
     return result;
   }
@@ skipping 87 matching lines @@
   static String _getElementIdentifier(String name, ReferenceKind kind) {
     if (kind == ReferenceKind.topLevelPropertyAccessor ||
         kind == ReferenceKind.propertyAccessor) {
       if (!name.endsWith('=')) {
         return name + '?';
       }
     }
     return name;
   }
 }