[webkit-dev] About fixing "old" layout bugs

Dan Bernstein mitz at apple.com
Tue Jun 1 22:12:19 PDT 2010

Hi Xianzhu,

On Jun 1, 2010, at 9:37 PM, Xianzhu Wang wrote:

> Hi,
> I'm new to webkit development, and I'd like to hear opinions about the problems I met.
> Now I'm trying to fix some "old" layout bugs, for example:
>   * white space preceding <br> (https://bugs.webkit.org/show_bug.cgi?id=37261)
>   * relative font-size (https://bugs.webkit.org/show_bug.cgi?id=18413)
>   * line breaking around some punctuations (https://bugs.webkit.org/show_bug.cgi?id=37698)
> Some people have warned me about the difficulty of fixing these bugs, and now I have realized it. Fixing the bugs themselves is not very difficult, for example, only 2 functional lines change can fix the first bug. However, the change will break more than 4000 existing layout tests mostly because trailing spaces preceding <br>s in current expectations of the tests (for example, "PASS " vs "PASS"). I tried to rebaseline all effected layout tests (for now on mac only), and the patch is about 6MB (Sorry I overlooked the "Bigfile" option when I submitted the patch, so I split it into 4 parts).
> My questions are:
> 1. The bugs violate the standards and cause some site compatibility issues. However, because the bugs are old, some web developers might treat them as features and depend on them, so fixing them might break some existing pages. Is there any existing policy about this problem?

Not sure. I think WebKit should not make a policy decision to diverge from the standard (quirks mode withstanding) unless WebKit developers are actively advocating a change to the relevant standard.

> Are these bugs worth fixing?

  * white space preceding <br> (https://bugs.webkit.org/show_bug.cgi?id=37261)

Unless I’m missing something, there is no known downside to fixing this bug. Seems worthwhile.

  * relative font-size (https://bugs.webkit.org/show_bug.cgi?id=18413)

Is this really a standards compliance issue or just compatibility with Firefox? If there is a standards issue, is there a subset of the change that’s sufficient for standards compliance? Unless WebKit is in violation of a standard here, I personally don’t consider this important, but I know that other contributors have agreed to this change in principle, and it’s just that the patch has been abandoned by the original author.

  * line breaking around some punctuations (https://bugs.webkit.org/show_bug.cgi?id=37698)

Seems worthwhile if it aligns WebKit with Firefox and IE. If moves away from IE compatibility, I wouldn’t do it. The main issue here is efficiency.

Personally, I think it’s good that you’re looking into such long-standing standards/compatibility issues!

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