src/jdk.scripting.nashorn/share/classes/jdk/nashorn/internal/parser/Parser.java

@@ -1102,16 +1102,18 @@
                 try {
                     init = assignmentExpression(!isStatement);
                 } finally {
                     defaultNames.pop();
                 }
-            } else if (varType == CONST) {
+            } else if (varType == CONST && isStatement) {
                 throw error(AbstractParser.message("missing.const.assignment", name.getName()));
             }
 
+            // Only set declaration flag on lexically scoped let/const as it adds runtime overhead.
+            final IdentNode actualName = varType == LET || varType == CONST ? name.setIsDeclaredHere() : name;
             // Allocate var node.
-            final VarNode var = new VarNode(varLine, varToken, sourceOrder, finish, name.setIsDeclaredHere(), init, varFlags);
+            final VarNode var = new VarNode(varLine, varToken, sourceOrder, finish, actualName, init, varFlags);
             vars.add(var);
             appendStatement(var);
 
             if (type != COMMARIGHT) {
                 break;

@@ -1245,11 +1247,10 @@
                 next();
             }
 
             expect(LPAREN);
 
-
             switch (type) {
             case VAR:
                 // Var declaration captured in for outer block.
                 vars = variableStatement(type, false, forStart);
                 break;