giving up on NaN, with one patch

David Herman dherman at mozilla.com
Tue Mar 26 19:58:32 PDT 2013


On Mar 26, 2013, at 7:19 PM, Sam Tobin-Hochstadt <samth at ccs.neu.edu> wrote:

> On Tue, Mar 26, 2013 at 10:15 PM, David Herman <dherman at mozilla.com> wrote:
>> 
>> ## Fix 2: Patch the semantics of writing non-writable properties
>> 
>> I agree with Sam that writing to a non-writable property is silly. We can fix the semantics so that it doesn't actually modify the value if SameValue holds. The only observable difference should be this NaN issue, which is what we wanted to fix in the first place.
>> 
>> I'm fine with either fix, but note that if we go with Fix 2, there's a finer distinction in the language than SameValue.
> 
> Jeff Walden pointed out that the semantics don't actually have this
> bug -- see the ValidateAndApplyPropertyDescriptor algorithm, which
> doesn't update in the SameValue case.

Ah, okay, even better. We still might want to modify the SameValue semantics in ES6 so that it truly is the finest distinction possible. But if it's not observable it doesn't matter.

Dave



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