Date constructor with negative value argument

[gfablima]

OS: Ubuntu 16.04 x86 chakra: 1.11.0.0-beta

Hi everyone,

I found an inconsistence on Date() with a negative value. I was looking on ES6 specification about this issue but I didn't found an answer, maybe the correct way is convert the -0 to +0 as V8 and SpiderMonkey do.

Steps to reproduce:

d = new Date(-0);
print(Object.is(d.getTime(), +0))

Actual results: false

Expected results: true

V8 and SpiderMonkey works as expected.

[rhuanjl]

I took a quick look at this. Relevant spec https://tc39.github.io/ecma262/#sec-date-value in particular point 4.(d) and then https://tc39.github.io/ecma262/#sec-timeclip

I believe that v8 and spidermonkey are correct and the fix would be to edit the date constructor here (after the if/else): https://github.com/Microsoft/ChakraCore/blob/d5479383f757b86676ef30ec50b1a8050d325e13/lib/Runtime/Library/JavascriptDate.cpp#L175-L183 To specifically check for -0 and convert to +0.

[dilijev]

Confirmed we're the only engine that diverges from spec here.

>eshost --tags jsvu -ise "Object.is(new Date(-0).getTime(), +0)"
## Source
print(Object.is(new Date(-0).getTime(), +0))

#### jsvu-ch
false

#### jsvu-jsc, jsvu-sm, jsvu-v8, jsvu-xs
true

[jackhorton]

I believe TimeClip is new -- I added it in Intl.cpp for use in DateTimeFormat, but it looks like it should be moved to somewhere more common and used in regular date parsing too.

[igor-simoes]

cinfuzz

[rhuanjl]

Marking this as a good first issue, should be less than 10 lines of code to fix though will also needed a test case which will be at leats the same again.

My previous comment highlights where the code change is needed - though also should check if can share code with Intl.cpp per jack's comment.

[Nazeeh21]

Can I work on this issue?

[rhuanjl]

Can I work on this issue?

Go for it, Read all the previous comments for a starting point - also please check the contributing guidelines. Tag me if you have any questions and if/when you open a PR.