Bug 128578 – Correct some uses of 'auto'

• Status: RESOLVED
• Resolution: FIXED
• Component: WebCore Misc.

[Brent Fulgham]

I recently noticed a number of places where we were using the following idiom:

for (auto rect : dirtyRects) {
    // ... do some stuff ...
}

The C++11 standard indicates that this produces something along the lines of:

"auto elem = *__begin;" which copies each element.

We should prefer to use "for (const auto& ..." wherever possible, or "for (auto&" in cases where we need to modify the elements.

[Brent Fulgham]

Created attachment 223809 [details]
Patch

[WebKit Commit Bot]

Comment on attachment 223809 [details]
Patch

Clearing flags on attachment: 223809

Committed r163882: <http://trac.webkit.org/changeset/163882>

[WebKit Commit Bot]

All reviewed patches have been landed.  Closing bug.

[Darin Adler]

I wholeheartedly agree that auto is not good when this churn happens. And I’m really glad you fixed this!

I don’t really prefer const auto& over auto&, though. I can’t think of any harm that comes from using auto&. If we only have const access to the collection, then the const works automatically. If we have non-const access, then it doesn’t seem worth the extra word just to narrow the access for the body of the loop.