1113718 - Uint8ClampedArray constructor rounds wrong

Status: RESOLVED FIXED

(Core :: JavaScript: Standard Library, defect)

Description

[Tom S. (please needinfo tschuster)]

new Uint8ClampedArray([2.6])
>> [2]
x = new Uint8ClampedArray([0])
x[0] = 2.6
x
>> [3]

Comment 1

[Lars T Hansen [:lth]]

Memo to self: need to check whether this affects SharedUint8ClampedArray too.

Comment 2

[Lars T Hansen [:lth]]

Tom, note that the bug here is really the opposite of what you reported.  ToUint8Clamp is supposed to round, not to truncate: http://people.mozilla.org/~jorendorff/es6-draft.html#sec-touint8clamp.

Ergo it's the conversion from the array-element (the first case in your test) that is buggy, not the conversion of assignment (the second case).

(SharedTypedArray does not allow the construction from array literal, and the assignment case behaves correctly.  Removing dependency.)

Comment 3

[Tom S. (please needinfo tschuster)]

Sorry Lars, but I think you might be confused somehow. Like I said "Uint8ClampedArray constructor rounds wrong", which is the first case.

Comment 4

[Lars T Hansen [:lth]]

(In reply to Tom Schuster [:evilpie] from comment #3)
> Sorry Lars, but I think you might be confused somehow. Like I said
> "Uint8ClampedArray constructor rounds wrong", which is the first case.

Indeed I misinterpreted the Summary.

Comment 5

[Tom S. (please needinfo tschuster)]

Attachment: new-clamped

Comment 6

[Tom S. (please needinfo tschuster)]

https://hg.mozilla.org/integration/mozilla-inbound/rev/9a45db9e1e28

Comment 7

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/mozilla-central/rev/9a45db9e1e28