quickjs-libc: handle null prototype objects in console.log

[bnoordhuis]

$ qjs -e 'console.log({__proto__:null})'
TypeError: toPrimitive
    at log (native)
    at <eval> (<cmdline>:1:1)

edit: originates in JS_ToCString() but that's no excuse for console.log to not show a human-readable representation

[bnoordhuis]

After thinking about it for a few minutes, maybe what is needed is something like V8's Value::ToDetailString: a stringifier that always returns something (preferably a useful human-readable representation) without side effects (doesn't call JS code, etc.)

Related to #630.

[chqrlie]

@bnoordhuis Hello! back from limboland!

repl already handles this via a local implementation of util.inspect. Doesn't v8 implement console.log as a wrapper around this?

Our implementation of console.log is very minimal and should be extended, albeit probably not with the full extend of util.inspect.

[bnoordhuis]

Hiya Charlie, welcome back.

Doesn't v8 implement console.log as a wrapper around this?

No, V8 only has stubs for console.log and friends; it leaves it up to the embedder.

A prime use case for ToDetailString is printing potentially poisoned/proxied objects (note that aforementioned awesome alliteration) like { toString() { return String(this) } }.

The motivation is that it should be easy for an embedder to - robustly! - print an object.

[saghul]

That SGTM!