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Web Compatibility #187

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jgraham opened this issue Oct 5, 2022 · 46 comments
Closed

Web Compatibility #187

jgraham opened this issue Oct 5, 2022 · 46 comments
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accepted An accepted proposal compat-bug-proposal Proposals for web compat bugs focus-area-proposal Focus Area Proposal

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@jgraham
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jgraham commented Oct 5, 2022

Description

A focus area for small bugs that cause known site compatibility issues, or documented problems for authors creating libraries or sites, but which are not part of a larger feature that's appropriate for its own focus area.

Rationale

Observed compatibility bugs which cause breakage for users are often not missing features, but specific cases where existing browsers don't follow the spec for features that are implemented. On their own these would be hard to fit into the Interop process since a focus area for a single bug, however important, is hard to weigh as part of the metric. However having a single focus area for these issues seems to have worked well in 2022, with browsers going from ~20% to ~100%, and fixing several bugs that were known to cause problems for users, but had not previously got priority.

Specification

All included bugs will have a specification (although in some cases it may be that "success" is changing the specification, testcase, and "conforming" implementations to match what's actually required by compat).

Inclusions will be motivated by observed compat issues (e.g. in webcompat.com or author-reported issues that they've had to work around when developing libraries.

Tests

Since this is a somewhat miscellaneous selection of bugs, it's anticipated that tests may be added from other focus areas where the overall focus area doesn't get priority but there are a small number of observed pain points which do get priority. During the selection process participants can request removal of any tests that would cause them to object to the proposal.

Suggested bugs / rationale (tests to be added):

@jgraham jgraham added the focus-area-proposal Focus Area Proposal label Oct 5, 2022
@jgraham
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jgraham commented Oct 5, 2022

Note that this is not yet a complete set of bugs / tests and I expect more to be added before the start of the selection period.

@gsnedders gsnedders added this to the Interop 2023 milestone Oct 5, 2022
@jgraham jgraham mentioned this issue Oct 5, 2022
@foolip foolip removed this from the Interop 2023 milestone Oct 7, 2022
@karlcow
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karlcow commented Oct 15, 2022

@karlcow karlcow added the compat-bug-proposal Proposals for web compat bugs label Oct 16, 2022
@gsnedders
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What's the status of #27? Does that make sense to include at this point?

@progers
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progers commented Oct 26, 2022

@karlcow , what approach did you use to generate the list of bugs in #187 (comment)?

@karlcow
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karlcow commented Oct 27, 2022

@progers So exactly what I said in the previous comment

  • failing in Chrome.
  • working in both Firefox and Safari

starting with the Interop List of Bugs opened on the Chromium project and checking which one mentioned the other browsers and selecting those where Firefox and Safari implementations were aligned. This is far to be perfect and the list could be a lot longer.

The why is maybe more interesting.

Webcompat issues are often created by the de facto implementation of the dominant market share browser. Both WebKit and Gecko teams can testify about this, where a bug is reported for a site breaking in Firefox or Safari, while they have the correct behavior, but the web developer assumed that the correct was Chrome's one, because the webdev worked exclusively with Chrome. The result is that other browsers have to implement quirks, site interventions or worse change the spec to align on chrome behavior.

So by fixing these paper cuts (if they are real bugs on Chrome side) would make it possible to avoid webcompat pressures on other engines and avoid confusion for web developers.

I hope it helps.

@bfgeek
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bfgeek commented Oct 27, 2022

I think the above approach can likely be improved upon. Bugs are marked "interop" in the chromium bug tracking in a somewhat haphazard fashion. E.g. the above list includes bugs filed by chromium engineers noting a difference - but no evidence this affects a real world site (bugs filed by web developers have a higher probability however).

Examples of the specific issue being a repeat issue (e.g. references from the webcompat.com project) would be helpful to indicate that the bug is an issue (the overlay example is great for example).

@bfgeek
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bfgeek commented Oct 27, 2022

Regarding crbug.com/1293302 specifically - we believe (from my understanding of the issue) is that the Blink behaviour is correct - and there are existing WPTs which are partially covering the issue (however they could be expanded):
https://wpt.fyi/results/css/css-grid/layout-algorithm/grid-flex-track-intrinsic-sizes-002.html

I'll double check with Ethan - but we'll likely WontFix this specific issue.

@jgraham
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jgraham commented Oct 27, 2022

From a gecko point of view "bug which got filed on blink but where the blink behaviour is now / was always correct" isn't a reason to remove the bug; it's a reason to ensure that it's fixed in gecko instead (it could, for example, be a case where we're operating on outdated assumptions about the correct behaviour). Of course it's even higher priority if we have evidence of widespread usage of the relevant feature, or active breakage. In this specific case I think the relevant gecko bug is https://bugzilla.mozilla.org/show_bug.cgi?id=1530097, which is indeed associated with a number of cases of breakage.

@gsnedders
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@jgraham what's your plan for this currently being "not yet a complete set of bugs"? how are we coming up with the list of compat bugs here?

@bfgeek
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bfgeek commented Oct 27, 2022

@jgraham - This is why we'd like to expand the grid/flex areas for 2023. A (very) quick look through Gecko's bugs reveals the following issues:
https://bugzilla.mozilla.org/show_bug.cgi?id=1719273
https://bugzilla.mozilla.org/show_bug.cgi?id=1779799
https://bugzilla.mozilla.org/show_bug.cgi?id=1681354
https://bugzilla.mozilla.org/show_bug.cgi?id=1791398
I believe all of these issues have WPT in the css-grid/ associated with them.

Ian

@jgraham
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jgraham commented Oct 27, 2022

I will audit the proposed bugs, and which have wpt tests. In at least some cases there are ad-hoc tests and it would be reasonably easy to port them to wpt if that hasn't already happened.

For the grid and flex bugs (and similar cases), if there's a gecko bug and it has any webcompat links in the see-also, or has a webompat priority set I think it makes sense to include in this cateogry. And if there's other parts of the feature with browser-specific failures that also implies at least a compat hazard so I'm also broadly in favour of including those.

@chrishtr
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Also, @karlcow I'm not sure if there are failing WPT tests representing each of the issues you listed. Do you know?

@jgraham
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jgraham commented Oct 28, 2022

So an updated list of proposed bugs, some of which still need to have testcases exported to wpt:

I've tried to look at all the suggestions for ones that are clearly causing real-world compat issues. @karlcow might have additional evidence of compat issues from the Chromium bugs (or indeed from WebKit bugs).

In terms of the general grid/flex/etc. carryover issues, I think it's unfortunate that we haven't had a clear plan for those before now. My ideal solution would have been to have specific proposals for each carry over, so they could be assessed along with other priorities, and then maybe merged into the compat bucket where appropriate. But we didn't have a clear process for that in time. The list above only includes the issues for which I could easily find compat problems. But I think we should have an additional discussion about how to handle carry-over in general.

@gsnedders
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Remove (or standardise?) overflow: overlay
https://bugs.chromium.org/p/chromium/issues/detail?id=55436

This seems like the wrong bug? https://bugs.chromium.org/p/chromium/issues/detail?id=1271942 and https://bugs.chromium.org/p/chromium/issues/detail?id=554361 (oh, maybe you lost the last digit?) seem more relevant.

And to note, the WebKit behaviour today is that it is a synonym of auto.

@karlcow
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karlcow commented Nov 1, 2022

I will look for more details. But what would be good to do probably for all of us is to have a list for 2024. Longterm Webcompat bugs have a nasty side effect as they can't be demonstrated or showed easily because 1. browsers change the standard behavior to avoid them, 2. implement quirks or 3. webdevs adjust their codepath with UA sniffing for sending different behaviors.

@bfgeek
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bfgeek commented Nov 2, 2022

For the replaced/aspect-ratio issues (e.g. https://bugzilla.mozilla.org/show_bug.cgi?id=1681354, https://bugzilla.mozilla.org/show_bug.cgi?id=1719273 ) all of the failures in the css-grid/grid-items are relevant.
https://wpt.fyi/results/css/css-grid/grid-items?label=master&label=experimental&aligned&view=subtest&q=firefox%3Afail%20aspect-ratio%20or%20replaced-element
Additionally there are multiple alignment tests:
https://wpt.fyi/results/css/css-grid/alignment?label=master&label=experimental&aligned&view=subtest&q=firefox%3Afail%20aspect-ratio%20or%20replaced

We also find that because Firefox doesn't implement step 3 & step 4 of the grid sizing algorithm this compounds the replaced/aspect-ratio issues:
https://bugzilla.mozilla.org/show_bug.cgi?id=1300366 (note blocking https://bugzilla.mozilla.org/show_bug.cgi?id=1719273)
There are many test cases testing that implementations are running steps 3 & 4 when I disable these steps in our code the relevant tests are:
https://wpt.fyi/results/css/css-grid?label=master&label=experimental&aligned&view=subtest&q=grid-template-flexible-rerun-track-sizing.html%20or%20grid-percent-rows-spanned-shrinkwrap-001.html%20or%20flex-sizing-rows-min-max-height-001.html%20or%20grid-percentage-rows-indefinite-height-002.html%20or%20grid-percentage-rows-indefinite-height-001.html%20or%20grid-content-alignment-second-pass-002.html%20

For https://bugzilla.mozilla.org/show_bug.cgi?id=1779799 / https://bugzilla.mozilla.org/show_bug.cgi?id=1530097
At least the test below - but there are likely other relevant test-cases.
https://wpt.fyi/results/css/css-grid/layout-algorithm/flex-and-intrinsic-sizes-002.html?label=experimental&label=master&aligned

FWIW most of the Firefox failures in the css-grid directory are related web-compat issues that web developers are running into.

@andreubotella
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andreubotella commented Nov 4, 2022

In Igalia we're starting to look into this issue, and we'll be fixing it at some point in the next year. The issue should probably be limited to the fact that Chromium counts an element boundary before a space as a line breaking opportunity, and you can reproduce this in a test case that doesn't require zoom. The fact that different zoom levels result in different line breaks even when the line width does not depend on the viewport size is a separate issue that should not count for Interop 2023.

However, as we were initially looking into this bug, we noticed that Webkit does seem to have this bug in some cases, although maybe not in all of the cases where Chromium has it, or it might have a separate but related bug. So should it still count for Interop 2023?

Edit: I had tested this bug in Webkit using Epiphany (Gnome Web), and apparently Safari doesn't have it.

@karlcow
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karlcow commented Nov 8, 2022

@jgraham for decoration box semantics
Probably this test makes it more obvious

https://software.hixie.ch/utilities/js/live-dom-viewer/saved/10939 is a test from crbug 855589

https://software.hixie.ch/utilities/js/live-dom-viewer/?saved=10982

Screenshot 2022-11-08 at 17 29 53

@karlcow
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karlcow commented Nov 8, 2022

These are all small (paper cut) bugs

I'm reviewing my own suggestions and I think we can remove a bunch of them.
My reduced list

PROBABLY

MAYBE

For @jgraham list, still reviewing them, but:

  • overflow: overlay will be a difficult one. https://cs.github.com/?q=%22overflow%3A+overlay+%22 doesn't return a lot of significant results. I wonder how many sites from the SeeAlso list in the bugzilla list have been fixed. And there's no obvious fix. If it is removed from Chrome and Safari, it is likely to create the same breakage than Firefox. Maybe this is acceptable. Safari could use Quirks, but that would leave Chrome without an easy solutions for removing it. Chrome doesn't have for now this flexibility. overflow: overlay on WebKit === overflow: auto
  • Flexbox/abspos paint order seems reasonable and I can see how it could create very annoying issues in terms of webdevs.

To be continued.

@jgraham
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jgraham commented Nov 8, 2022

overflow: overlay will be a difficult one

I think it's acceptable if the outcome is that we standardise the Blink/WebKit behaviour and Firefox adopts that (although obviously that's not my preferred outcome). https://github.com/webcompat/knowledge-base/blob/main/data/overflow-overlay.yml has links to a lot of examples of this causing breakage in the wild.

https://bugs.chromium.org/p/chromium/issues/detail?id=811172 is another Blink/WebKit bug that has caused a number of compat problems.

@gsnedders
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So what is this proposal at this point? Is it just @jgraham's list of proposed bugs in #187 (comment), or is it a broader union of the listed bugs here?

@foolip
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foolip commented Nov 11, 2022

I'm commenting on proposals for features that came up in State of CSS 2022 going by the list in #248. Obviously this focus area cannot be named directly, but it is notable that flexbox is still top of mind. A lot of that is due to flex gap not being available in older browser versions still in use, but also comments like "Flexbox seems to have some overflow bugs still. (min-width: 0; fix, anyone?)"

overflow: overlay is actually mentioned once directly as well.

@chrishtr
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@gsnedders I'm treating this proposal as tracking the union of @jgraham's issues and the ones from @karlcow.

@foolip
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foolip commented Nov 15, 2022

text-transform capitalize behavior after dot (.)

Is this still on the table, given the discussion in w3c/csswg-drafts#8031? After internal review of the tests, this is one we're not sure about including.

@jgraham
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jgraham commented Nov 15, 2022

That's not in @karlcow's reduced list #187 (comment) so I consider it already removed. But in any case, removing it isn't a problem.

@nt1m
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nt1m commented Nov 15, 2022

Can all the testcases be exported to WPT? Makes it easier to assess the proposals generally.

@jgraham
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jgraham commented Nov 15, 2022

Per request we can also consider the overflow: overlay test removed since there's a pending spec issue there (see w3c/csswg-drafts#8063; hopefully we can all ship it as an alias of overflow:auto and get interop, but it doesn't need to be part of this issue).

@jgraham
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jgraham commented Nov 15, 2022

Can all the testcases be exported to WPT? Makes it easier to assess the proposals generally.

Yes, but realistically I doubt we can do that by Thursday.

If there are concerns with specific tests once they're ported to wpt I think it would be possible to deal with that later.

@karlcow
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karlcow commented Dec 7, 2022

@jgraham Should we add https://bugzilla.mozilla.org/show_bug.cgi?id=1772305 to the webcompat focus area.

It creates this compat issue for Safari while doing the right thing.
webcompat/web-bugs#106690

@jgraham
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jgraham commented Dec 9, 2022

That seems reasonable to me c.f. @emilio and @foolip who would need to find someone from Google to look at this.

@chrishtr
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chrishtr commented Dec 9, 2022

That seems reasonable to me c.f. @emilio and @foolip who would need to find someone from Google to look at this.

You're talking about this bug, right? Is that a bug in Gecko? Emilio's comment guesses that.

@jgraham
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jgraham commented Jan 12, 2023

Tests update for the areas I suggested:

Move to flex/grid:

  • Flexbox/abspos paint order
  • Firefox and Chrome differ on whether to honor a definite width on an image descendant of a grid
    • Seems like the issue is maybe already fixed? If it turns out there's a fix with a bug, we can add that.
  • Increase sizes to accommodate spanning items crossing flexible tracks

@jgraham
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jgraham commented Jan 12, 2023

Still need to identify / add tests from #187 (comment) and https://bugzilla.mozilla.org/show_bug.cgi?id=1772305 (cc @karlcow)

@bfgeek
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bfgeek commented Jan 12, 2023

What about issues mentioned in #187 (comment) ?

@jgraham
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jgraham commented Jan 12, 2023

@bfgeek I thought those tests were being added to grid / flexbox focus areas. I agree they're important and shouldn't be lost.

@bfgeek
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bfgeek commented Jan 12, 2023

I thought those tests were being added to grid / flexbox focus areas. I agree they're important and shouldn't be lost.

Should:

  • Flexbox/abspos paint order
  • Increase sizes to accommodate spanning items crossing flexible tracks

Also be dropped from this particular area as they are already in the grid/flexbox focus areas?

@bfgeek
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bfgeek commented Jan 12, 2023

(Just after consistency about how we think of these)

@andreubotella
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andreubotella commented Jan 12, 2023

I'm currently looking into fixing this in Blink, and working on a more comprehensive WPT test. Note that the Chromium bug isn't just about white-space: break-spaces, but about how it interacts with element boundaries when line breaking.

Also, I don't think https://wpt.fyi/results/css/CSS2/text/text-align-white-space-003.xht is related to this issue at all, since this is about whether text-align: justify does anything when the line has no collapsible white space, which is not a requirement (keyword "may") in the spec:

If an element’s white space is not collapsible, then the UA is not required to adjust its text for the purpose of justification and may instead treat the text as having no justification opportunities.

@jgraham
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jgraham commented Jan 13, 2023

@andreubotella how soon do you expect to have tests in wpt? If not in the next coupld of weeks, could we start by merging and tagging the test I ported and then replacing it once your tests are landed?

@jgraham
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jgraham commented Jan 13, 2023

@bfgeek I don't mind moving those into flexbox/grid tests instead of here.

@bfgeek
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bfgeek commented Jan 13, 2023

I don't mind moving those into flexbox/grid tests instead of here.
@jgraham sg - to be clear I don't mind either way - just consistency. The two tests for those are already part of the flex/grid test suites.

@andreubotella
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@andreubotella how soon do you expect to have tests in wpt? If not in the next coupld of weeks, could we start by merging and tagging the test I ported and then replacing it once your tests are landed?

I already opened a PR: web-platform-tests/wpt#37985

@johannesodland
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I know it might be too late, but I'll post this combat issue here and leave it up to you to decide if it can be included in interop 2023 or not.

There are some interop issues on ::first-letter when it comes to including punctuation and whitespace. This prevents some international authors and users from using ::first-letter in their sites, as it will not match their typographic conventions. It's a small issue, but it excludes many authors and users from using the pseudo element.

The spec includes punctuation and whitespace before and after the initial letter, as defined in css-pseudo-4. Browsers are not interoperable and supports punctuation and whitespace to a varying degree:

Safari:
Whitespace: supported
Punctuation: partial support

Chrome:
Whitespace: not supported
Punctuation: partial support

Firefox:
Whitespace: not supported
Punctuation: partial support

There is a crude test in WPT. It currently fails for all browsers:
https://wpt.fyi/results/css/css-pseudo/first-letter-punctuation-and-space.html?label=master&label=experimental&aligned

There are open issues in all browsers here:
https://bugs.chromium.org/p/chromium/issues/detail?id=1163175
https://bugs.webkit.org/show_bug.cgi?id=179815
https://bugzilla.mozilla.org/show_bug.cgi?id=602459

@jgraham
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jgraham commented Jan 18, 2023

I know it might be too late, but I'll post this combat issue here and leave it up to you to decide if it can be included in interop 2023 or not.

Unfortunately the proposal period for Interop 2023 is indeed over.

You are of course welcome (and encouraged!) to propose ::first-letter for a future round of Interop. However, based on the description so far it doesn't sound like it would be part of a Web Compatibility focus area; this is usually for browser differences in existing features that are breaking sites in the wild. Features that are poorly supported across browsers typically get their own top-level proposal.

@foolip foolip added the accepted An accepted proposal label Feb 1, 2023
@foolip
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foolip commented Feb 1, 2023

Thank you for proposing Web Compatibility for inclusion in Interop 2023.

We are pleased to let you know that this proposal was accepted as the Web Compat 2023 focus area. You can follow the progress of this Focus Area on the Interop 2023 dashboard.

For an overview of our process, see the proposal selection summary. Thank you for contributing to Interop 2023!

Posted on behalf of the Interop team.

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