Fix for conditional expressions

lib/src/checker/resolver.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.
 
 /// Encapsulates how to invoke the analyzer resolver and overrides how it
 /// computes types on expressions to use our restricted set of types.
 library dev_compiler.src.checker.resolver;
 
 import 'package:analyzer/analyzer.dart';
 import 'package:analyzer/src/generated/ast.dart';
@@ skipping 378 matching lines @@
       // variety of types, especially when we get to JS interop.
       var args = node.argumentList.arguments;
       if (args.isNotEmpty && args.first is SimpleStringLiteral) {
         var coreLib = _typeProvider.objectType.element.library;
         var classElem = coreLib.getType(args.first.stringValue);
         if (classElem != null) node.staticType = classElem.type;
       }
     }
   }
 
+  @override
+  visitConditionalExpression(ConditionalExpression node) {
+    // TODO(vsm): The static type of a conditional should be the LUB of the
+    // then and else expressions.  The analyzer appears to compute dynamic when
+    // one or the other is the null literal.  Remove this fix once the
+    // corresponding analyzer bug is fixed:
+    // https://code.google.com/p/dart/issues/detail?id=22854
+    super.visitConditionalExpression(node);
+    if (node.staticType.isDynamic) {
+      var thenExpr = node.thenExpression;
+      var elseExpr = node.elseExpression;
+      if (thenExpr.staticType.isBottom) {
+        node.staticType = elseExpr.staticType;
+      } else if (elseExpr.staticType.isBottom) {
+        node.staticType = thenExpr.staticType;
+      }
+    }
+  }
+
   // Review note: no longer need to override visitFunctionExpression, this is
   // handled by the analyzer internally.
   // TODO(vsm): in visitbinaryExpression: check computeStaticReturnType result?
-  // TODO(vsm): in visitConditionalExpression: check... LUB in rules?
   // TODO(vsm): in visitFunctionDeclaration: Should we ever use the expression
   // type in a (...) => expr or just the written type?
 
 }
 
 class RestrictedTypeResolverVisitor extends TypeResolverVisitor {
   RestrictedTypeResolverVisitor(
       Library library, Source source, TypeProvider typeProvider)
       : super.con1(library, source, typeProvider);
 
@@ skipping 36 matching lines @@
         element.returnType.isDynamic &&
         node.returnType == null) {
       var type = searchTypeFor(element.enclosingElement.type, element);
       if (type != null && !type.returnType.isDynamic) {
         element.returnType = type.returnType;
       }
     }
     return res;
   }
 }