Bug 159543 – padStart/padEnd with Infinity produces unexpected result

• Status: RESOLVED
• Resolution: FIXED
• Component: JavaScriptCore

[Joseph Pecoraro]

Summary:
padStart/padEnd with Infinity produces unexpected result

Test:
>>> "foo".padStart(Infinity, "x")
"nullfoo"
>>> "foo".padEnd(Infinity, "x")
"foonull"

Expected:
"Error: Out of memory" for a string that would be > Max String Size (JSString::MaxLength is std::numeric_limits<int32_t>::max()).

Spec:
<https://tc39.github.io/ecma262/#sec-string.prototype.padend>
<https://tc39.github.io/ecma262/#sec-string.prototype.padstart>

Note the spec does special case the empty fill string, so that can be handled even if the maxLength is Infinity:

> 1. Let O be ? RequireObjectCoercible(this value).
> 2. Let S be ? ToString(O).
> 3. Let intMaxLength be ? ToLength(maxLength).
> 4. Let stringLength be the number of elements in S.
> 5. If intMaxLength is not greater than stringLength, return S.
> 6. If fillString is undefined, let filler be a String consisting solely of the code unit 0x0020 (SPACE).
> 7. Else, let filler be ? ToString(fillString).
> 8. If filler is the empty String, return S.
> ...

[Joseph Pecoraro]

Created attachment 283105 [details]
[PATCH] Proposed Fix

[Joseph Pecoraro]

Created attachment 283106 [details]
[PATCH] Proposed Fix

Fixed double ChangeLog.

[Joseph Pecoraro]

Created attachment 283109 [details]
[PATCH] For Landing

Some improvements to the builtins that Ben saw.

[WebKit Commit Bot]

Comment on attachment 283109 [details]
[PATCH] For Landing

Clearing flags on attachment: 283109

Committed r202966: <http://trac.webkit.org/changeset/202966>