185156 2018-04-30 20:07:27 -0700 JavaScriptCore should throw SyntaxError when a variable is already declared inside the "with" scope 2018-08-08 08:57:46 -0700 1 1 1 Unclassified WebKit JavaScriptCore Safari 11 Unspecified Linux NEW P2 Normal --- 1 baac webkit-unassigned isol2 mark.lam saam ysuzuki oldest_to_newest 1419235 0 baac 2018-04-30 20:07:27 -0700 Hi, there is an inconsistency when a variable is declared twice as "var" and "let" inside the "with" scope. JavaScriptCore should not accept the redeclaration and indicate an error. OS: Ubuntu 17.10 JavaScriptCore: 606.1.9.4 Step to reproduce: with({}) { var a; let a; } Actual result: Pass without failures Expected result: SyntaxError: Cannot declare a variable twice V8 and SpiderMonkey raises an exception as expected. 1419263 1 saam 2018-04-30 22:30:20 -0700 This is surprising given: if (b) { var a; let a; } Is not a syntax error. Since with scopes don't require a block as their statement, e.g ```with({}) 20;``` is valid, I would guess this might be a bug in those other engines. Can you point me to where the spec says this should be a syntax error? 1448758 2 isol2 2018-08-08 08:57:46 -0700 Hi Saam, sorry for delay... baac left from our project she did not answered your question in time. We reported this issue on JSC and Chakra already confirmed after discussion (https://github.com/Microsoft/ChakraCore/issues/5076). Another similar case can be found in this code: { let x; eval('var x;'); } JSC and Chakra should not hoist the var past the let declaration without throwing redeclaration. V8 and Spidermonkey throws a SyntaxError as expected. cinfuzz