[PATCH v11 10/10] jscript: Return the correct string for Object.toString(null) in ES5+ modes.

[Gabriel Ivăncescu]

On 30/11/2021 23:20, Jacek Caban wrote:
> On 11/29/21 5:31 PM, Gabriel Ivăncescu wrote:
>> +    else if(function->proc == Object_toString && ctx->version >= 
>> SCRIPTLANGUAGEVERSION_ES5) {
>> +        jsstr_t *ret;
>> +        if(!r)
>> +            return S_OK;
>> +        ret = jsstr_alloc(L"[object Null]");
>> +        if(!ret)
>> +            return E_OUTOFMEMORY;
>> +        *r = jsval_string(ret);
>> +        return S_OK;
>> +    }
> 
> 
> This is ugly. I think that what you observe is a change in how ES5 
> treats 'this' argument in builtin functions. It allows 'this' to be of 
> any type for builtin function. The conversion to object (or using a 
> global object in place of null) happens only when we enter JS function, 
> if I read it right. To support this properly, I'm afraid that we'd need 
> to pass 'this' as jsval to builtin functions. We wouldn't need any 
> special casing for toString() then.
> 

Interesting, I did not realize builtin functions were special in regards 
to the "this" context. I'll send this separately later then, but passing 
jsval to builtin functions would also help with fixing the undefined 
case (since toString reports [object Undefined] then), so it's on the 
right track for sure.