[MERGE #5181 @akroshg] Incorrect object shorthand error in lambda

Merge pull request #5181 from akroshg:shorthand

The object definition at lambda param should be treated as object pattern. However we had deduced that we are on right side of an expression. Which is clearly not the case.
Fixed that, by let the statement boundary determines that there is any shorthand error deferred and then throw error.

Author: akroshg

lib/Parser/Parse.cpp

@@ -8423,7 +8423,6 @@ ParseNodePtr Parser::ParseExpr(int oplMin,
 
     this->GetScanner()->Capture(&termStart);
 
-    bool deferredErrorFoundOnLeftSide = false;
     bool savedDeferredInitError = m_hasDeferredShorthandInitError;
     m_hasDeferredShorthandInitError = false;
 
@@ -8607,7 +8606,9 @@ ParseNodePtr Parser::ParseExpr(int oplMin,
             *pfLikelyPattern = !!fLikelyPattern;
         }
 
-        if (m_token.tk == tkDArrow)
+        if (m_token.tk == tkDArrow
+            // If we have introduced shorthand error above in the ParseExpr, we need to reset if next token is the assignment.
+            || (m_token.tk == tkAsg && oplMin <= koplAsg))
         {
             m_hasDeferredShorthandInitError = false;
         }
@@ -8703,8 +8704,6 @@ ParseNodePtr Parser::ParseExpr(int oplMin,
         }
     }
 
-    deferredErrorFoundOnLeftSide = m_hasDeferredShorthandInitError;
-
     // Process a sequence of operators and operands.
     for (;;)
     {
@@ -8929,13 +8928,6 @@ ParseNodePtr Parser::ParseExpr(int oplMin,
         }
     }
 
-    if (m_hasDeferredShorthandInitError && !deferredErrorFoundOnLeftSide)
-    {
-        // Raise error only if it is found not on the right side of the expression.
-        // such as  <expr> = {x = 1}
-        Error(ERRnoColon);
-    }
-
     m_hasDeferredShorthandInitError = m_hasDeferredShorthandInitError || savedDeferredInitError;
 
     if (NULL != pfCanAssign)

test/es6/destructuring_bugs.js

@@ -30,6 +30,9 @@ var tests = [
       assert.doesNotThrow(function () { eval("for([] = ((...a) => {}) in '' ) { }"); }, "Having a lambda function with rest parameter as initializer should not assert and is a valid syntax");
       assert.doesNotThrow(function () { eval("[[[] = [function () { }] ] = []]"); }, "Nested array has array pattern which has function expression is a valid syntax");
       assert.doesNotThrow(function () { eval("var a = ({x = 1}) => x;"); }, "Lambda has Object destructuring as parameter which has initializer on shorthand is a valid syntax");
+      assert.doesNotThrow(function () { eval("var a = (b, {x = 1}) => x;"); }, "Lambda has Object destructuring as a second parameter which has initializer on shorthand is a valid syntax");
+      assert.doesNotThrow(function () { eval("var a = ({x = 1}, b) => x;"); }, "Lambda has Object destructuring as first parameter which has initializer on shorthand is a valid syntax");
+      assert.throws(function () { eval("let a = ({name = 'foo'}, 1) = {}"); }, ReferenceError, "Object shorthand will behave as pattern when on left-hand side and should not throw syntax error");
     }
   },
   {