We can only use JavaScript's String.split and String.+ if both inputs are Strings.

R=karlklose@google.com

Review URL: https://codereview.chromium.org//23494057

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart@27557 260f80e4-7a28-3924-810f-c04153c831b5

Author: ngeoffray@google.com

sdk/lib/_internal/compiler/implementation/ssa/interceptor_simplifier.dart

@@ -264,7 +264,7 @@ class SsaSimplifyInterceptors extends HBaseVisitor
     // they have side effects.
     HInstruction instruction;
     if (selector.isGetter()) {
-      instruction= new HInvokeDynamicGetter(
+      instruction = new HInvokeDynamicGetter(
           selector,
           node.element,
           <HInstruction>[constant, node.inputs[1]],

sdk/lib/_internal/compiler/implementation/ssa/optimize.dart

@@ -299,13 +299,17 @@ class SsaInstructionSimplifier extends HBaseVisitor
         }
       } else if (input.isString(compiler)) {
         if (selector.applies(backend.jsStringSplit, compiler)) {
-          if (node.inputs[2].isString(compiler)) {
+          HInstruction argument = node.inputs[2];
+          if (argument.isString(compiler) && !argument.canBeNull()) {
             target = backend.jsStringSplit;
           }
         } else if (selector.applies(backend.jsStringOperatorAdd, compiler)) {
           // `operator+` is turned into a JavaScript '+' so we need to
-          // make sure the receiver is not null.
-          if (node.inputs[2].isString(compiler) && !input.canBeNull()) {
+          // make sure the receiver and the argument are not null.
+          HInstruction argument = node.inputs[2];
+          if (argument.isString(compiler)
+              && !argument.canBeNull()
+              && !input.canBeNull()) {
             target = backend.jsStringOperatorAdd;
           }
         } else if (selector.applies(backend.jsStringToString, compiler)

tests/corelib/string_operations_with_null_test.dart

@@ -0,0 +1,19 @@
+// Copyright (c) 2013, 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.
+
+import "package:expect/expect.dart";
+import "../language/compiler_annotations.dart";
+
+@DontInline()
+returnStringOrNull() {
+  () => 42;
+  return new DateTime.now().millisecondsSinceEpoch == 0 ? 'foo' : null;
+}
+
+main() {
+  Expect.throws(() => 'foo' + returnStringOrNull(),
+                (e) => e is ArgumentError);
+  Expect.throws(() => 'foo'.split(returnStringOrNull()),
+                (e) => e is ArgumentError || e is NoSuchMethodError);
+}