Allow 'in' to terminate expressions in the control

of a for...in loop fixes #5203.
chakra-core · May 23, 2018 · f095914 · f095914
1 parent 249b4af
commit f095914
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Showing 4 changed files with 17 additions and 5 deletions.
diff --git a/lib/Parser/Parse.cpp b/lib/Parser/Parse.cpp
@@ -8337,7 +8337,7 @@ void Parser::DeferOrEmitPotentialSpreadError(ParseNodePtr pnodeT)
     }
 }
 
-bool Parser::IsTerminateToken()
+bool Parser::IsTerminateToken(bool inTerminate)
 {
     return (m_token.tk == tkRCurly ||
         m_token.tk == tkRBrack ||
@@ -8346,6 +8346,7 @@ bool Parser::IsTerminateToken()
         m_token.tk == tkColon ||
         m_token.tk == tkComma ||
         m_token.tk == tkLimKwd ||
+        (m_token.tk == tkIN && inTerminate) ||
         this->GetScanner()->FHadNewLine());
 }
 
@@ -8358,7 +8359,7 @@ template<bool buildAST>
 bool Parser::ParseOptionalExpr(ParseNodePtr* pnode, bool fUnaryOrParen, int oplMin, BOOL *pfCanAssign, BOOL fAllowIn, BOOL fAllowEllipsis, _Inout_opt_ IdentToken* pToken)
 {
     *pnode = nullptr;
-    if (IsTerminateToken())
+    if (IsTerminateToken(!fAllowIn))
     {
         return false;
     }
@@ -8489,7 +8490,7 @@ ParseNodePtr Parser::ParseExpr(int oplMin,
 
         if (nop == knopYield)
         {
-            if (!ParseOptionalExpr<buildAST>(&pnodeT, false, opl, NULL, TRUE, fAllowEllipsis))
+            if (!ParseOptionalExpr<buildAST>(&pnodeT, false, opl, NULL, fAllowIn, fAllowEllipsis))
             {
                 nop = knopYieldLeaf;
                 if (buildAST)
@@ -8839,7 +8840,7 @@ ParseNodePtr Parser::ParseExpr(int oplMin,
             // ArrowFunction/AsyncArrowFunction is part of AssignmentExpression, which should terminate the expression unless followed by a comma
             if (m_token.tk != tkComma)
             {
-                if (!(IsTerminateToken()))
+                if (!(IsTerminateToken(!fAllowIn)))
                 {
                     Error(ERRnoSemic);
                 }

diff --git a/lib/Parser/Parse.h b/lib/Parser/Parse.h
@@ -780,7 +780,7 @@ class Parser
     template<bool buildAST> ParseNodePtr ParseMemberList(LPCOLESTR pNameHint, uint32 *pHintLength, tokens declarationType = tkNone);
     template<bool buildAST> IdentPtr ParseSuper(bool fAllowCall);
 
-    bool IsTerminateToken();
+    bool IsTerminateToken(bool inTerminate);
 
     // Used to determine the type of JavaScript object member.
     // The values can be combined using bitwise OR.

diff --git a/test/es6/generators-syntax.js b/test/es6/generators-syntax.js
@@ -212,6 +212,14 @@ var tests = [
             assert.throws(function () { eval("function *gf() { (a = (yield) => {}) => {}; }"); }, SyntaxError, "yield expression is disallowed within arrow function default parameter expression in nested case too", "The use of a keyword for an identifier is invalid");
         }
     },
+    {
+        name : "yield is allowed before 'in' in a for loop control but not elsewhere bug issue #5203",
+        body : function () {
+            assert.doesNotThrow(function () { eval("function* gf() {for(var a = yield in {});}"); }, "Yield is allowed before 'in' in a for loop");
+            assert.throws(function () { eval("function* gf() {var a = yield in {};}"); }, SyntaxError, "Yield is not allowed before 'in' when not declaring a loop");
+            assert.throws(function () { eval("function* gf() {yield in {};}"); }, SyntaxError, "Yield is not allowed before 'in' when not declaring a loop");
+        }
+    }
 ];
 
 testRunner.runTests(tests, { verbose: WScript.Arguments[0] != "summary" });
diff --git a/test/es6/lambda-expr.js b/test/es6/lambda-expr.js
@@ -33,3 +33,6 @@ catch (e)
 {
     print(e.message);
 }
+
+// Legal case, lambda in object inside for()
+for (var i = () => {} in {});