Add optional message argument to assert statements in the VM.

runtime/vm/parser.cc

Index: runtime/vm/parser.cc
diff --git a/runtime/vm/parser.cc b/runtime/vm/parser.cc
index 7df47357276501a91de28dd5a11ad8b013836c5c..cc209c6d636873a3758bd1447348a7a15b220506 100644
--- a/runtime/vm/parser.cc
+++ b/runtime/vm/parser.cc
@@ -47,6 +47,7 @@ DEFINE_FLAG(bool, trace_parser, false, "Trace parser operations.");
 DEFINE_FLAG(bool, supermixin, false, "Allow super calls in mixins.");
 DEFINE_FLAG(bool, warn_mixin_typedef, true, "Warning on legacy mixin typedef.");
 DEFINE_FLAG(bool, link_natives_lazily, false, "Link native calls lazily");
+DEFINE_FLAG(bool, assert_message, false, "Allow message in assert statements");

[Lasse Reichstein Nielsen, 2015/08/28 18:51:59]

Should it be "enable_assert_message" instead?

[Ivan Posva, 2015/09/04 06:39:31]

Please coordinate across the implementations. Since this is only temporary, I am
fine with either flag name.

 
 DECLARE_FLAG(bool, lazy_dispatchers);
 DECLARE_FLAG(bool, load_deferred_eagerly);
@@ -9115,12 +9116,17 @@ AstNode* Parser::MakeStaticCall(const String& cls_name,
 }
 
 
-AstNode* Parser::MakeAssertCall(intptr_t begin, intptr_t end) {
+AstNode* Parser::MakeAssertCall(intptr_t begin, intptr_t end,
+                                AstNode* message) {
   ArgumentListNode* arguments = new(Z) ArgumentListNode(begin);
   arguments->Add(new(Z) LiteralNode(begin,
       Integer::ZoneHandle(Z, Integer::New(begin))));
   arguments->Add(new(Z) LiteralNode(end,
       Integer::ZoneHandle(Z, Integer::New(end))));
+  if (message == NULL) {
+    message = new(Z) LiteralNode(end, Instance::ZoneHandle(Z));
+  }
+  arguments->Add(message);
   return MakeStaticCall(Symbols::AssertionError(),
                         Library::PrivateCoreLibName(Symbols::ThrowNew()),
                         arguments);
@@ -9152,15 +9158,24 @@ AstNode* Parser::ParseAssertStatement() {
   const intptr_t condition_pos = TokenPos();
   if (!I->flags().asserts() && !I->flags().type_checks()) {

[Ivan Posva, 2015/09/04 06:39:31]

This line here testing the flag configuration is wrong. I am in process of
fixing it, but we might need a change in the test harness to be able to actually
write a functioning regression test. Thanks for touching code that has not been
touched in a long while.

     SkipExpr();
+    if (FLAG_assert_message && CurrentToken() == Token::kCOMMA) {
+      ConsumeToken();
+      SkipExpr();
+    }
     ExpectToken(Token::kRPAREN);
     return NULL;
   }
   AstNode* condition = ParseAwaitableExpr(kAllowConst, kConsumeCascades, NULL);
+  AstNode* message = NULL;
   const intptr_t condition_end = TokenPos();
+  if (FLAG_assert_message && CurrentToken() == Token::kCOMMA) {
+    ConsumeToken();
+    message = ParseAwaitableExpr(kAllowConst, kConsumeCascades, NULL);
+  }
   ExpectToken(Token::kRPAREN);
   condition = InsertClosureCallNodes(condition);
   condition = new(Z) UnaryOpNode(condition_pos, Token::kNOT, condition);
-  AstNode* assert_throw = MakeAssertCall(condition_pos, condition_end);
+  AstNode* assert_throw = MakeAssertCall(condition_pos, condition_end, message);
   return new(Z) IfNode(
       condition_pos,
       condition,