[debug] use catch prediction flag for promise rejections.

src/parsing/parser.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/parsing/parser.h"
 
 #include "src/api.h"
 #include "src/ast/ast.h"
 #include "src/ast/ast-expression-rewriter.h"
 #include "src/ast/ast-expression-visitor.h"
@@ skipping 2965 matching lines @@
   int pos = position();
 
   Block* try_block;
   {
     ReturnExprScope no_tail_calls(function_state_,
                                   ReturnExprContext::kInsideTryBlock);
     try_block = ParseBlock(NULL, CHECK_OK);
   }
 
   Token::Value tok = peek();
+  bool catch_for_promise_reject = false;
   if (tok != Token::CATCH && tok != Token::FINALLY) {
-    ReportMessage(MessageTemplate::kNoCatchOrFinally);
-    *ok = false;
-    return NULL;
+    if (allow_natives() && tok == Token::MOD) {
+      Consume(Token::MOD);
+      catch_for_promise_reject = true;
+      tok = peek();
+      DCHECK_EQ(Token::CATCH, tok);

[Dan Ehrenberg, 2016/07/21 21:07:33]

Nit: I wonder if we should use CHECK here; if it weren't native-only, we'd want
to make a good syntax error. We do have good syntax errors for other natives
cases, like runtime functions called with the wrong number of arguments.

+    } else {
+      ReportMessage(MessageTemplate::kNoCatchOrFinally);
+      *ok = false;
+      return NULL;
+    }
   }
 
   Scope* catch_scope = NULL;
   Variable* catch_variable = NULL;
   Block* catch_block = NULL;
   TailCallExpressionList tail_call_expressions_in_catch_block(zone());
   if (tok == Token::CATCH) {
     Consume(Token::CATCH);
 
     Expect(Token::LPAREN, CHECK_OK);
@@ skipping 97 matching lines @@
   }
 
   // Simplify the AST nodes by converting:
   //   'try B0 catch B1 finally B2'
   // to:
   //   'try { try B0 catch B1 } finally B2'
 
   if (catch_block != NULL && finally_block != NULL) {
     // If we have both, create an inner try/catch.
     DCHECK(catch_scope != NULL && catch_variable != NULL);
-    TryCatchStatement* statement = factory()->NewTryCatchStatement(
-        try_block, catch_scope, catch_variable, catch_block, kNoSourcePosition);
+    TryCatchStatement* statement;
+    if (catch_for_promise_reject) {
+      statement = factory()->NewTryCatchStatementForPromiseReject(
+          try_block, catch_scope, catch_variable, catch_block,
+          kNoSourcePosition);
+    } else {
+      statement = factory()->NewTryCatchStatement(try_block, catch_scope,
+                                                  catch_variable, catch_block,
+                                                  kNoSourcePosition);
+    }
+
     try_block = factory()->NewBlock(NULL, 1, false, kNoSourcePosition);
     try_block->statements()->Add(statement, zone());
     catch_block = NULL;  // Clear to indicate it's been handled.
   }
 
   TryStatement* result = NULL;
   if (catch_block != NULL) {
     // For a try-catch construct append return expressions from the catch block
     // to the list of return expressions.
     function_state_->tail_call_expressions().Append(
@@ skipping 3943 matching lines @@
   node->Print(Isolate::Current());
 }
 #endif  // DEBUG
 
 #undef CHECK_OK
 #undef CHECK_OK_CUSTOM
 #undef CHECK_FAILED
 
 }  // namespace internal
 }  // namespace v8