Do not permit binding over catch parameters in for-of

src/parser.cc

Index: src/parser.cc
diff --git a/src/parser.cc b/src/parser.cc
index d993d20595de80567f267e8410dfe77edcbe450c..51d665ad5596c98062ee5bf392e12e360f44aedc 100644
--- a/src/parser.cc
+++ b/src/parser.cc
@@ -3617,13 +3617,13 @@ Statement* Parser::ParseForStatement(ZoneList<const AstRawString*>* labels,
 
         DCHECK(parsing_result.declarations.length() == 1);
         Block* init_block = nullptr;
+        const AstRawString* name = parsing_result.SingleName();
 
         // special case for legacy for (var/const x =.... in)
         if (!IsLexicalVariableMode(parsing_result.descriptor.mode) &&
             parsing_result.declarations[0].initializer != nullptr) {
           VariableProxy* single_var = scope_->NewUnresolved(
-              factory(), parsing_result.SingleName(), Variable::NORMAL,
-              each_beg_pos, each_end_pos);
+              factory(), name, Variable::NORMAL, each_beg_pos, each_end_pos);
           init_block = factory()->NewBlock(
               nullptr, 2, true, parsing_result.descriptor.declaration_pos);
           init_block->AddStatement(
@@ -3636,6 +3636,16 @@ Statement* Parser::ParseForStatement(ZoneList<const AstRawString*>* labels,
               zone());
         }
 
+        // For some reason, we can't bind over catch parameters in for-of.
+        if (mode == ForEachStatement::ITERATE &&
+            IsDeclaredAsCatchParameter(scope_, name)) {
+          ParserTraits::ReportMessageAt(parsing_result.first_initializer_loc,
+                                        MessageTemplate::kVarRedeclaration,
+                                        name);
+          *ok = false;
+          return nullptr;
+        }
+
         // Rewrite a for-in/of statement of the form
         //
         //   for (let/const/var x in/of e) b
@@ -4816,6 +4826,13 @@ void Parser::CheckConflictingVarDeclarations(Scope* scope, bool* ok) {
   }
 }
 
+bool Parser::IsDeclaredAsCatchParameter(Scope* scope,
+                                        const AstRawString* name) {
+  for (; scope != NULL; scope = scope->outer_scope())
+    if (scope->is_catch_scope() && scope->LookupLocal(name)) return true;
+  return false;
+}
+
 
 // ----------------------------------------------------------------------------
 // Parser support