util: logging symbols should convert using String(symbol)

[domenic]

var symbol = Symbol("My symbol");

console.log(symbol); // fine, logs Symbol(My symbol)
console.log("foo", symbol); // throws

Output:

$ iojs test.js
Symbol(My symbol)
util.js:34
      str += ' ' + x;
                 ^
TypeError: Cannot convert a Symbol value to a string
    at Console.exports.format (util.js:34:18)
    at Console.log (console.js:36:34)
    at Object.<anonymous> (c:\Users\Domenic\Dropbox\GitHub\whatwg\streams\reference-implementation\test.js:4:9)
    at Module._compile (module.js:444:26)
    at Object.Module._extensions..js (module.js:462:10)
    at Module.load (module.js:339:32)
    at Function.Module._load (module.js:294:12)
    at Function.Module.runMain (module.js:485:10)
    at startup (node.js:111:16)
    at node.js:799:3

Note that the correct way to stringify a symbol is with the explicit conversion, String(symbol), instead of implicitly with the + sign.

I can get to this after work if nobody else does first.

[vkurchatkin]

Is it the correct behaviour though? I thought it was v8 bug

[domenic]

Yeah, this is correct per spec and several TC39 meetings. It is dangerous to allow symbols to be implicitly converted to strings (and in some cases you just flat out can't do it, e.g. obj[prop] usually does an implicit string conversion). However explicit conversion is fine.

[cjihrig]

Closed by ed3b057