hack: treat const in for(const x in y) as let.

idea from classilla/tenfourfox#541
roytam1 · Feb 1, 2019 · f0dd403 · f0dd403
1 parent 7edbd8b
commit f0dd403
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Showing 2 changed files with 5 additions and 5 deletions.
diff --git a/js/src/frontend/BytecodeEmitter.cpp b/js/src/frontend/BytecodeEmitter.cpp
@@ -5496,7 +5496,7 @@ BytecodeEmitter::emitIterator()
 bool
 BytecodeEmitter::emitForInOrOfVariables(ParseNode* pn)
 {
-    MOZ_ASSERT(pn->isKind(PNK_VAR) || pn->isKind(PNK_LET));
+    MOZ_ASSERT(pn->isKind(PNK_VAR) || pn->isKind(PNK_LET) || pn->isKind(PNK_CONST));
 
     // ES6 specifies that loop variables get a fresh binding in each iteration.
     // This is currently implemented for C-style for(;;) loops, but not
@@ -5518,7 +5518,7 @@ BytecodeEmitter::emitForInOrOfVariables(ParseNode* pn)
         if (!emitVariables(pn, DefineVars))
             return false;
     } else {
-        MOZ_ASSERT(pn->isKind(PNK_LET));
+        MOZ_ASSERT(pn->isKind(PNK_LET) || pn->isKind(PNK_CONST));
         if (!emitVariables(pn, InitializeVars))
             return false;
     }

diff --git a/js/src/frontend/Parser.cpp b/js/src/frontend/Parser.cpp
@@ -4583,10 +4583,10 @@ Parser<ParseHandler>::declarationPattern(Node decl, TokenKind tt, BindData<Parse
         if (*forHeadKind != PNK_FORHEAD) {
             // |for (const ... in ...);| and |for (const ... of ...);| are
             // syntax errors for now.  We'll fix this in bug 449811.
-            if (handler.declarationIsConst(decl)) {
+            /*if (handler.declarationIsConst(decl)) {
                 report(ParseError, false, pattern, JSMSG_BAD_CONST_DECL);
                 return null();
-            }
+            }*/
 
             if (!checkDestructuringPattern(data, pattern))
                 return null();
@@ -4788,7 +4788,7 @@ Parser<ParseHandler>::declarationName(Node decl, TokenKind tt, BindData<ParseHan
             if (isForIn || isForOf) {
                 // XXX Uncomment this when fixing bug 449811.  Until then,
                 //     |for (const ... in/of ...)| remains an error.
-                //constRequiringInitializer = false;
+                constRequiringInitializer = false;
 
                 *forHeadKind = isForIn ? PNK_FORIN : PNK_FOROF;
             } else {