LGTM1 to ship in M111 (while monitoring the relevant UMAs from M110) after
merging back the use counters.

On Thu, Jan 12, 2023 at 4:40 PM Rune Lillesveen <[email protected]>
wrote:

>
>
> On Thu, Jan 12, 2023 at 1:00 PM Yoav Weiss <[email protected]> wrote:
>
>>
>>
>> On Wed, Jan 11, 2023 at 7:53 AM Yoav Weiss <[email protected]>
>> wrote:
>>
>>> thanks! :)
>>>
>>> On Wed, Jan 11, 2023 at 6:42 AM Byungwoo Lee <[email protected]> wrote:
>>>
>>>> Something wrong with the citation style of the previous mail. I'll send
>>>> the reply again.
>>>>
>>>> >>> OK, so for where we're risking seeing more fallbacks than before,
>>>> but according to your manual inspection, that seems fine?
>>>> >> Yes, I think so.
>>>> >> Based on the usage metrics, only about 0.5 % of page loads could be
>>>> affected by this feature.
>>>>
>>>
>> Just to clarify - 0.5% is about 2 orders of magnitude higher than the
>> levels of breakage we're typically comfortable with.
>> But from our discussion it seems that the levels of actual breakage are
>> likely to be significantly smaller.
>>
>> Considering the manual investigation on the top pages (only 1 of of 10 is
>>>> for `:where()`, and the rest are for `:has()`. no urls for `:is()`), the
>>>> ratio of the `:where()` is likely to be much less than 0.5 %.
>>>> > In the manual inspection, how many function calls had a mix of valid
>>>> and invalid selectors? (that would be impacted by this change)
>>>> There is no mix of valid and invalid in the manual inspection for the
>>>> top URLs. :has() and :where() are used only with empty argument or valid
>>>> argument.
>>>>
>>>>
>>>> >> Will it be better to add a feature for this change and add some
>>>> metrics (something like, how many page loads use :has() with both valid and
>>>> invalid selector) before releasing it to stable?
>>>> > Adding a feature (including a base_feature) to the `:has` change
>>>> would be good. Would you be able to merge that back to 110?
>>>> > I think we should tie the `:has` change to this intent. The risk
>>>> profile seems similar.
>>>> I made a CL that adds 'CSSPseudoHasNonForgivingParsing' feature (
>>>> https://chromestatus.com/feature/6177049203441664) for the change:
>>>> - https://chromium-review.googlesource.com/c/chromium/src/+/4151453
>>>>
>>>> The CL also adds two metrics so that we can get usecounter of the cases
>>>> that the change affects:
>>>> - CSSPseudoHasContainsMixOfValidAndInvalid : ':has(a, :foo)'
>>>> - CSSPseudoIsWhereContainsMixOfValidAndInvalid : ':is(a, :foo)',
>>>> ':where(a, :foo)'
>>>>
>>>>  I'll try to merge the CL to 110 branch after it landed.
>>>>
>>>
>> That'd be great to land and merge back.
>> +Rune Lillesveen <[email protected]> - can you help make that happen?
>>
>
> Yes.
>
> Once we have that in place, I'd be comfortable with turning on the feature
>> on M111, and carefully watching the (internal) UMA use counter stats for
>> Beta as it rolls out, and revert it if we'd see that actual breakage is
>> likely to be larger than expected.
>>
>> Rune, Byungwoo - what do you think?
>>
>
> Sgtm.
>
>
>>
>>>>
>>>> 2023년 1월 11일 수요일 오후 2시 33분 10초 UTC+9에 Byungwoo Lee님이 작성:
>>>>
>>>>>
>>>>>
>>>>> 2023년 1월 9일 월요일 오후 7시 36분 34초 UTC+9에 [email protected]님이 작성:
>>>>> On Mon, Jan 9, 2023 at 11:12 AM Byungwoo Lee <[email protected]> wrote:
>>>>> Thanks! I replied again. :)
>>>>>
>>>>> 2023년 1월 6일 금요일 오후 7시 50분 43초 UTC+9에 [email protected]님이 작성:
>>>>> On Thu, Jan 5, 2023 at 4:59 PM Byungwoo Lee <[email protected]> wrote:
>>>>> Added missing links.
>>>>>
>>>>> 2023년 1월 6일 금요일 오전 12시 52분 25초 UTC+9에 Byungwoo Lee님이 작성:
>>>>>
>>>>> Thanks for asking!
>>>>>
>>>>>
>>>>> > Is this change covered by a base feature flag?
>>>>>
>>>>> This is behind 'CSSAtSupportsAlwaysNonForgivingParsing' flag, and the
>>>>> flag doesn't have 'base_feature' field yet. I'll add the field to the
>>>>> feature before enable it.
>>>>>
>>>>>
>>>>> > Can you clarify if the ':has()' behavior will change here or not?
>>>>> This last sentence seems to contradict the original message of the intent.
>>>>>
>>>>> > Can you confirm that both these cases won't break?
>>>>>
>>>>> There's a bit of twisted history here, so it would be better to answer
>>>>> these two questions at once. (Sorry for the long answer!)
>>>>>
>>>>>
>>>>> 1. What can this feature change?
>>>>>
>>>>> After this feature enabled, `@supports selector()` can return
>>>>> different result when it checks forgiving-parsing pseudo class.
>>>>>
>>>>> For example, `@supports selector(:where(:foo, a))` returns true now
>>>>> (forgiving parsing drops invalid `:foo` inside `:where()`, so the
>>>>> `:where(:foo, a)` becomes a valid selector `:where(a)` after forgiving
>>>>> parsing), but it will return false after this feature enabled
>>>>> (`:where(:foo, a)` will be invalid inside `@supports selector()`).
>>>>>
>>>>> OK, so for where we're risking seeing more fallbacks than before, but
>>>>> according to your manual inspection, that seems fine?
>>>>>
>>>>> Yes, I think so.
>>>>> Based on the usage metrics, only about 0.5 % of page loads could be
>>>>> affected by this feature. Considering the manual investigation on the top
>>>>> pages (only 1 of of 10 is for `:where()`, and the rest are for `:has()`. 
>>>>> no
>>>>> urls for `:is()`), the ratio of the `:where()` is likely to be much less
>>>>> than 0.5 %.
>>>>>
>>>>> In the manual inspection, how many function calls had a mix of valid
>>>>> and invalid selectors? (that would be impacted by this change)
>>>>> There is no mix of valid and invalid in the manual inspection for the
>>>>> top URLs. :has() and :where() are used only with empty argument or valid
>>>>> argument.
>>>>>
>>>>>
>>>>>
>>>>> But I cannot say that this feature will not affect at all, or that
>>>>> will be the exact numbers that this feature actually affects after
>>>>> 110(unforgiving `:has()`) released.
>>>>>
>>>>> I think we can get the number at about Apr (the next month after the
>>>>> 110 released).
>>>>>
>>>>> Will it be better to wait more so that we can see the number only for
>>>>> `:where()` and `:is()`?
>>>>>
>>>>>
>>>>> 2. How is this feature related to `:has()`?
>>>>>
>>>>> This `@supports` behavior change was applied to the spec [1] while
>>>>> resolving an issue of `:has()` [2]. At that time, `:has()` was a
>>>>> forgiving-parsing pseudo class. So this feature was able to change the
>>>>> result of `@supports selector(:has(:foo, a))` at first.
>>>>>
>>>>> But it is not true now since `:has()` is changed to unforgiving while
>>>>> resolving the jQuery `:has()` conflict issue [3].
>>>>>
>>>>> Hmm, so the behavior change to `:has` landed
>>>>> <https://chromium-review.googlesource.com/c/chromium/src/+/4090967>
>>>>> in M110 without a feature flag nor an intent. How confident are we that
>>>>> this is safe?
>>>>> ^^ +Rune Lillesveen
>>>>>
>>>>> I think it would not make a critical issue since,
>>>>> 1. the change only affects `:has()` validity if the `:has()` contains
>>>>> both valid and invalid arguments (e.g. `:has(:foo, a) { ... }`), and it
>>>>> will not be used often in the wild.
>>>>>     I got a comment saying something similar while landing the jQuery
>>>>> workaround  -
>>>>> https://github.com/w3c/csswg-drafts/issues/7676#issuecomment-1235724730
>>>>> 2. the change fixes the inconsistency in the existing :has() validity
>>>>> logic.
>>>>>     - Currently, `:has()`, `:has(:foo)` and `:has(:foo, :bar)` are
>>>>> invalid, but `:has(:foo, a)` is valid.
>>>>>     - After the change merged, all the above are invalid selector.
>>>>> 3. Basically, the conflict from the change(making `:has()`
>>>>> unforgiving) can be easily fixed by changing the selector. (e.g. change
>>>>> `:has(:foo, a) {...}` to `:has(:where(:foo, a)) {...}` or
>>>>> `where(:has(:foo), :has(a)) {...}`),
>>>>>
>>>>> Will it be better to add a feature for this change and add some
>>>>> metrics (something like, how many page loads use :has() with both valid 
>>>>> and
>>>>> invalid selector) before releasing it to stable?
>>>>>
>>>>> Adding a feature (including a base_feature) to the `:has` change would
>>>>> be good. Would you be able to merge that back to 110?
>>>>>
>>>>> I think we should tie the `:has` change to this intent. The risk
>>>>> profile seems similar.
>>>>>
>>>>> I made a CL that adds 'CSSPseudoHasNonForgivingParsing' feature (
>>>>> https://chromestatus.com/feature/6177049203441664) for the change:
>>>>> - https://chromium-review.googlesource.com/c/chromium/src/+/4151453
>>>>>
>>>>> The CL also adds two metrics so that we can get usecounter of the
>>>>> cases that the change affects:
>>>>> - CSSPseudoHasContainsMixOfValidAndInvalid : ':has(a, :foo)'
>>>>> - CSSPseudoIsWhereContainsMixOfValidAndInvalid : ':is(a, :foo)',
>>>>> ':where(a, :foo)'
>>>>>
>>>>>  I'll try to merge the CL to 110 branch after it landed.
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> Now this feature doesn't change the `@supports selector(:has(:foo,
>>>>> a))` result. `@supports selector(:has(:foo, a))` returns always false
>>>>> regardless of this feature since `:has(:foo, a)` is an invalid selector
>>>>> both inside and outside of `@supports selector()`.
>>>>>
>>>>>
>>>>> 3. The history about empty `:has()`
>>>>>
>>>>> This is a tricky part.
>>>>> When the 105(the first `:has()` enabled version) is released to
>>>>> stable, a workaround was merged [4] to avoid the jQuery conflict issue.
>>>>>
>>>>> At that time, `:has()` was a forgiving-parsing pseudo class, so
>>>>> `:has(:foo)` and `:has()` should be a valid selector.
>>>>>
>>>>> But the workaround changed the behavior - make `:has()` invalid when
>>>>> all the arguments are dropped.
>>>>> - `:has()` is invalid because it doesn't have any argument.
>>>>> - `:has(:foo)` is invalid because it doesn't have any argument after
>>>>> the invalid argument `:foo` is dropped.
>>>>> - `:has(:foo, a)` is valid because it has a valid argument `a` after
>>>>> the invalid argument `:foo` is dropped.
>>>>>
>>>>> Last December, the jQuery conflict issue was resolved [3] and it was
>>>>> applied to 110 [5] - make `:has()` unforgiving.
>>>>> - `:has()` is invalid because it doesn't have any argument.
>>>>> - `:has(:foo)` is invalid because it has an invalid argument `:foo`.
>>>>> - `:has(:foo, a)` is invalid because it has an invalid argument `:foo`.
>>>>>
>>>>> Due to this, the result of `@supports selector(:has())` has been false
>>>>> since 105.
>>>>> OK, so the `:has` change only differs from currently shipped behavior
>>>>> if there's a mix of invalid and valid arguments as part of the supports
>>>>> statement. And given the fact that the M110 shipped behavior is stricter,
>>>>> what we may see is more sites fallback if they have such :has supports
>>>>> statements, but we wouldn't expect real breakage, because presumably the
>>>>> fallbacks are reasonable?
>>>>> Yes,  exactly. As I replied at above, the 110 change fixes the
>>>>> inconsistency of :has() validity, and the selector expression can be 
>>>>> simply
>>>>> fixed if it creates actual problem on a site.
>>>>>
>>>>> In the perspective of the jQuery `:has()` conflict issue, this change
>>>>> fixes remaining bugs that the jQuery workaround doesn't fix.
>>>>> Currently jQuery has a bug on `$(':has(span, :contains(abc))')` since
>>>>> `@supports selector()` returns true for the selector and
>>>>> `querySelectorAll()` doesn't throw invalid selector exception.
>>>>> After making `:has()` unforgiving, jQuery can do its custom traversal
>>>>> for `:contains()` since `@supports selector()` returns false and
>>>>> `querySelectorAll()` throws exception.
>>>>>
>>>>>
>>>>>
>>>>> 4. Why does this feature not affect URLs that use WordPress yootheme?
>>>>>
>>>>> Because it checks with empty `:has()` - `@supports not
>>>>> selector(:has())`.
>>>>>
>>>>> `@supports not selector(:has())` has been always true since 105, and
>>>>> it will still be true after this feature enabled because this feature
>>>>> doesn't affect unforgiving parsing.
>>>>>
>>>>> The strange point is that the statement is useless(because it is
>>>>> always true) and semantically incorrect [6].
>>>>>
>>>>>
>>>>> 5. Why does this feature not affect URLs that use jQuery `:has()`?
>>>>>
>>>>> Because the jQuery `has()` conflict issue was already resolved by
>>>>> making `:has()` unforgiving [3], [5], and this feature doesn't affect
>>>>> unforgiving parsing.
>>>>>
>>>>>
>>>>> 6. In short,
>>>>>
>>>>> This feature will not affect `:has()` inside `@supports selector()`.
>>>>>
>>>>> This feature can affects `:is()` or `where()` inside `@supports
>>>>> selector()`. (only when its argument is empty or invalid)
>>>>>
>>>>>
>>>>> Hope that this has clarified the question.
>>>>>  --------
>>>>>
>>>>> [1]
>>>>> https://github.com/w3c/csswg-drafts/commit/3a2efb33d12f6667d6142e89609a982978b49223
>>>>>
>>>>> [2] https://github.com/w3c/csswg-drafts/issues/7280
>>>>>
>>>>> [3]
>>>>> https://github.com/w3c/csswg-drafts/issues/7676#issuecomment-1341347244
>>>>>
>>>>> [4]
>>>>> https://chromium.googlesource.com/chromium/src/+/2b818b338146d89e524c4fabc2c6f7fd7776937a
>>>>>
>>>>> [5]
>>>>> https://chromiumdash.appspot.com/commit/7278cf3bf630c7791ba4b4885eb7da64dc16eab2
>>>>> [6] It uses `@supports` like this:
>>>>>      @supports not selector(:has()) {
>>>>>       .woocommerce:has(> .woocommerce-MyAccount-navigation){
>>>>>         display:flex;
>>>>>         justify-content:space-between
>>>>>       }
>>>>>     }
>>>>>     I'm not sure but the `not` seems to be a workaround to make the
>>>>> block works.
>>>>>
>>>>>
>>>>> 2023년 1월 5일 목요일 오후 7시 8분 7초 UTC+9에 [email protected]님이 작성:
>>>>> Thanks!!
>>>>>
>>>>> A couple of questions below, plus another one: Is this change
>>>>> covered by a base feature
>>>>> <https://chromium.googlesource.com/chromium/src/+/main/third_party/blink/renderer/platform/RuntimeEnabledFeatures.md#generate-a-instance-from-a-blink-feature>
>>>>>  flag?
>>>>>
>>>>> On Wed, Jan 4, 2023 at 12:34 PM Byungwoo Lee <[email protected]> wrote:
>>>>> I checked the top URLs in the ChromeStatus page. (TL;DR - this feature
>>>>> looks not affect the existing behavior of the top URLs)
>>>>>
>>>>> I was able to categorize the URLs as below.
>>>>>
>>>>> 1. Checking `:has()` support
>>>>> - Most of the URLs use `@supports` to check `:has()` support.
>>>>> - `@support` behavior will not be changed for `:has()` (We can ignore
>>>>> this case since `:has()` will be unforgiving after 110 released)
>>>>>
>>>>> Can you clarify if the ':has()' behavior will change here or not? This
>>>>> last sentence seems to contradict the original message of the intent.
>>>>>
>>>>> - There are 2 sub cases:
>>>>>      - URLs using WordPress yootheme [1]
>>>>>      - URLs using jQuery `has()` [2]
>>>>>
>>>>> Can you confirm that both these cases won't break?
>>>>>
>>>>>
>>>>> 2. Checking `:where()` support
>>>>> - Only one URL(https://learn.ooznest.co.uk/) uses `@supports` to
>>>>> check `:where()` support.
>>>>> - `@supports` behavior will be changed for `:where()` after this
>>>>> feature enabled, but it will not affect the behavior of the web page since
>>>>> the page handles both support and not support case[3].
>>>>>
>>>>> The only problem that I can see from the top URLs is checking
>>>>> `:where()` support, but it looks very rare case and it may be already
>>>>> handled like learn.ooznest.co.uk.
>>>>> (I was able to see some incorrect usages while checking[4], but I
>>>>> think it is another discussion of checking empty `:where()`, `:has()`)
>>>>>
>>>>> I think that this feature does not have critical impact on the
>>>>> existing behavior. And as shared previously, Safari and Firefox already
>>>>> changed their implementations.
>>>>>
>>>>> How about shipping this?
>>>>>
>>>>> ------------
>>>>>
>>>>> [1] 6 URLs (6/10):
>>>>>       - https://lavalmore.gr/
>>>>>       - https://www.kussenwereld.nl/
>>>>>       - https://thelocustgroveflowers.com/
>>>>>       - https://shop.bmgi.com.au/
>>>>>       - https://badaptor.com/
>>>>>       - https://suicidprev.se/
>>>>>     'theme1.css' of yootheme contains `@supports not selector(:has())
>>>>> {...}` statement.
>>>>>     (e.g.
>>>>> https://thelocustgroveflowers.com/wp-content/themes/locust-ff/css/theme.1.css?ver=1669913762
>>>>> )
>>>>>     The `@supports not...` statement looks weird since the conditional
>>>>> block contains rules using `:has()`.
>>>>>
>>>>> [2] 2 URLs (2/10):
>>>>>       - https://www.midroog.co.il/
>>>>>       - https://whadam.tistory.com/
>>>>>
>>>>> [3] A stylesheet file has `@supports selector(:where()) {...}` and
>>>>> `@supports not selector(:where()) {...}` statement.
>>>>>     (
>>>>> https://d3015z1jd0uox2.cloudfront.net/Assets/Guide/black/guide-all-j81VMtmAdGEcl2BaHR40jA.css
>>>>> )
>>>>>
>>>>> [4] Passing empty `:has()` or `:where()` to `@supports selector()` to
>>>>> check whether a browser supports the pseudo class.
>>>>>     (e.g. `@supports not selector(:has())`, `@supports
>>>>> selector(:where())`)
>>>>>
>>>>> 2023년 1월 3일 화요일 오후 6시 18분 31초 UTC+9에 Byungwoo Lee님이 작성:
>>>>> Hello Yoav,
>>>>>
>>>>> Chrome status shows the number from stable now.
>>>>>
>>>>> I checked these metrics.
>>>>> - https://chromestatus.com/metrics/feature/timeline/popularity/4361
>>>>> (CSSAtSupportsDropInvalidWhileForgivingParsing)
>>>>> - https://chromestatus.com/metrics/feature/timeline/popularity/976
>>>>> (CSSAtRuleSupports)
>>>>>
>>>>> According to the above metrics, some pages will be affected by this
>>>>> feature but it seems to be a relatively small fraction:
>>>>> - Only 0.50 % of page loads are dropping invalid selector while
>>>>> parsing forgiving selector inside '@supports selector()'.
>>>>> - 41.10% of page loads are using '@supports', but only 1.21%
>>>>> (0.5/41.1) of the page loads are dropping invalid selector while parsing
>>>>> forgiving selector inside '@supports selector()'.
>>>>> - Less than 0.01 % of top sites are dropping invalid selector while
>>>>> parsing forgiving selector inside '@supports selector()'.
>>>>> - 50.89% of top URLs are using '@supports', but less than 0.02%
>>>>> (0.01/50.89) of the URLs are dropping invalid selector while parsing
>>>>> forgiving selector inside '@supports selector()'.
>>>>>
>>>>> Can we move forward based on this? Or should I check another number?
>>>>>
>>>>> 2022년 12월 10일 토요일 오전 1시 26분 57초 UTC+9에 Byungwoo Lee님이 작성:
>>>>> Hello,
>>>>>
>>>>> The 108 branch is shipping to stable now, but the numbers from stable
>>>>> doesn't seems to be applied to the ChromeStatus stats yet. It seems that
>>>>> the stable numbers will be applied at Jan. 1st.
>>>>> - https://chromestatus.com/metrics/feature/timeline/popularity/4361
>>>>>
>>>>> I'll reschedule the feature release to 112 so that we can revisit this
>>>>> thread when we can get the numbers from stable.
>>>>>
>>>>> Thank you!
>>>>>
>>>>> p.s. 1
>>>>> This feature is not related to :has() anymore since :has() is now
>>>>> unforgiving:
>>>>> - Issue resolution:
>>>>> https://github.com/w3c/csswg-drafts/issues/7676#issuecomment-1341347244
>>>>> - CL :
>>>>> https://chromium-review.googlesource.com/c/chromium/src/+/4090967
>>>>> This feature only affects :is()/:where() inside @supports.
>>>>>
>>>>> p.s. 2
>>>>> Once I get the stable number, I'll provide a comparison of these two
>>>>> numbers that I can get from the ChromeStatus stats:
>>>>> - Percentage of page loads that drop invalid while forgiving parsing
>>>>> inside @supports selector
>>>>>   (https://chromestatus.com/metrics/feature/timeline/popularity/4361)
>>>>> - Percentage of page loads that use @supports rule
>>>>>   (https://chromestatus.com/metrics/feature/timeline/popularity/976)
>>>>>
>>>>> The comparison doesn't prove anything, but I think we can at least
>>>>> guess how much the @supports change affects the existing behavior:
>>>>> Assuming the current numbers in the above links are from stable, about
>>>>> 40% of the loaded pages use @supports rule, but only 0.002% of the loaded
>>>>> pages hit the case of dropping invalid selector while forgiving selector
>>>>> parsing inside @supports. By simply comparing the numbers, I think we can
>>>>> say that 1/20000 of the @supports rule usages will be affected by the
>>>>> feature.
>>>>>
>>>>> 2022년 10월 10일 월요일 오후 11시 18분 41초 UTC+9에 Byungwoo Lee님이 작성:
>>>>> To continue this thread after getting the stable Chrome's use counter,
>>>>> I changed the estimated milestone of this feature from 109 to 111.
>>>>> I'll share the use counter after the version 108 released.
>>>>>
>>>>> Thank you!
>>>>>
>>>>> 2022년 9월 29일 목요일 오전 11시 52분 43초 UTC+9에 Byungwoo Lee님이 작성:
>>>>>
>>>>>
>>>>> On 9/27/22 10:07, Byungwoo Lee wrote:
>>>>>
>>>>>
>>>>> On 9/24/22 00:40, Yoav Weiss wrote:
>>>>>
>>>>>
>>>>> On Fri, Sep 23, 2022 at 5:25 PM Byungwoo Lee <[email protected]> wrote:
>>>>>
>>>>> Hello Yoav and Mike,
>>>>>
>>>>> Thanks for the feedback! I replied inline.
>>>>> On 9/23/22 22:18, Yoav Weiss wrote:
>>>>>
>>>>>
>>>>> On Fri, Sep 23, 2022 at 3:15 PM Mike Taylor <[email protected]>
>>>>> wrote:
>>>>> Hi Byungwoo,
>>>>>
>>>>> On 9/23/22 4:34 AM, Byungwoo Lee wrote:
>>>>> Contact emails [email protected]
>>>>>
>>>>> Specification
>>>>> https://drafts.csswg.org/css-conditional-4/#support-definition-ext
>>>>>
>>>>> Summary
>>>>>
>>>>> Some functional selectors are parsed forgivingly. (e.g. :is(), :has())
>>>>> If an argument of the functional selectors is unknown or invalid, the
>>>>> argument is dropped but the selector itself is not invalidated. To provide
>>>>> a way of detecting the unknown or invalid arguments in those functional
>>>>> selectors, this feature applies the CSS Working Group issue resolution: -
>>>>> @supports uses non-forgiving parsing for all selectors (
>>>>> https://github.com/w3c/csswg-drafts/issues/7280#issuecomment-1143852187
>>>>> )
>>>>> Am I understanding correctly that content that now uses a functional
>>>>> selector argument that's invalid may break as a result of this?
>>>>> If so, do we have usecounters to that effect?
>>>>>
>>>>> Yes it can change the previous behavior.
>>>>>
>>>>> This changes the selector parsing behavior only for the selectors
>>>>> inside @supports selector().
>>>>>
>>>>> So if authors expected true for '@supports
>>>>> selector(:is(:some-invalid-selector))', this feature will break it because
>>>>> the return value will be changed to false after this feature is enabled.
>>>>>
>>>>> I'm not sure that we have the usecounters of the case: counting drop
>>>>> of invalid selector inside @supports selector.
>>>>>
>>>>> If it doesn't exists but it is needed, I think we can add it. Will it
>>>>> be better to add it to get use counters before ship it?
>>>>>
>>>>> Yeah, knowing the order of magnitude of potential breakage would be
>>>>> good.
>>>>> I landed a CL to add the use counter:
>>>>>
>>>>> https://chromiumdash.appspot.com/commit/d060459d174c468a78d69d4e2a12925e0e7ab216
>>>>>
>>>>> It counts the drop of invalid selector while forgiving selector
>>>>> parsing inside @supports selector(). We can see the stats with
>>>>> CSSAtSupportsDropInvalidWhileForgivingParsing(4361):
>>>>> https://chromestatus.com/metrics/feature/timeline/popularity/4361
>>>>>
>>>>> This will be in 108 version so hopefully we can get the use counter
>>>>> after the version is released.
>>>>>
>>>>>    - beta (Oct 27)
>>>>>    - stable (Nov 29)
>>>>>
>>>>> I'll share the stats when it released.
>>>>>
>>>>> Thanks!
>>>>>
>>>>>
>>>>>
>>>>> Blink component Blink
>>>>> <https://bugs.chromium.org/p/chromium/issues/list?q=component:Blink>
>>>>>
>>>>> TAG review
>>>>>
>>>>> TAG review status Not applicable
>>>>>
>>>>> Can you expand on why you think a TAG review is not needed here?
>>>>>
>>>>> I thought that we don't need TAG review and the reason was
>>>>>
>>>>> - This is already specified in the spec:
>>>>>     https://drafts.csswg.org/css-conditional-4/#support-definition-ext
>>>>> <https://drafts.csswg.org/css-conditional-4/#support-definition-ext>
>>>>>
>>>>> - Firefox already landed it:
>>>>>   https://bugzilla.mozilla.org/show_bug.cgi?id=1789248
>>>>>
>>>>> Will it be better to change the TAG review status to 'Pending'?
>>>>>
>>>>>
>>>>> Risks
>>>>>
>>>>>
>>>>> Interoperability and Compatibility
>>>>>
>>>>> *Gecko*: Shipped/Shipping
>>>>> https://bugzilla.mozilla.org/show_bug.cgi?id=1789248
>>>>>
>>>>> *WebKit*: Positive
>>>>>
>>>>> *Web developers*: Positive
>>>>> Can you please link to these signals?
>>>>>
>>>>>
>>>>> WebKit:
>>>>>
>>>>> - Explained about this in a blog post:
>>>>>   https://webkit.org/blog/13096/css-has-pseudo-class/
>>>>>
>>>>> Web developers:
>>>>>
>>>>> - Thumbs ups in the CSSWG issue:
>>>>>    https://github.com/w3c/csswg-drafts/issues/7280
>>>>>
>>>>> - jQuery applied the spec:
>>>>>   https://github.com/jquery/jquery/pull/5107
>>>>>
>>>>>
>>>>> Rego let me know what I missed (Thanks!), so I'm updating this.
>>>>>
>>>>> This specification change has been implemented in WebKit as well as
>>>>> Firefox:
>>>>> https://bugs.webkit.org/show_bug.cgi?id=244808
>>>>>
>>>>> I updated the 'Safari views' and 'Tag review' in the chromestatus
>>>>> accordingly.
>>>>>
>>>>>
>>>>> *WebKit:* Shipped/Shipping
>>>>> https://bugs.webkit.org/show_bug.cgi?id=244808
>>>>>
>>>>>
>>>>> *Tag review*
>>>>> No TAG review
>>>>>
>>>>>
>>>>> - This is already specified in the spec:
>>>>>     https://drafts.csswg.org/css-conditional-4/#support-definition-ext
>>>>>
>>>>> - Firefox and WebKit already implemented it:
>>>>>   https://bugzilla.mozilla.org/show_bug.cgi?id=1789248
>>>>>   https://bugs.webkit.org/show_bug.cgi?id=244808
>>>>>
>>>>>
>>>>> *Tag review status*
>>>>> pending
>>>>>
>>>>>
>>>>> Could this update affect the shipping decisions?
>>>>>
>>>>> thanks,
>>>>> Mike
>>>>>
>>>>>
>>>>> --
>>>>> You received this message because you are subscribed to the Google
>>>>> Groups "blink-dev" group.
>>>>> To unsubscribe from this group and stop receiving emails from it, send
>>>>> an email to [email protected].
>>>>> To view this discussion on the web visit
>>>>> https://groups.google.com/a/chromium.org/d/msgid/blink-dev/b03b90af-3911-40b4-dd6f-b12764826cf1%40chromium.org
>>>>> <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/b03b90af-3911-40b4-dd6f-b12764826cf1%40chromium.org?utm_medium=email&utm_source=footer>
>>>>> .
>>>>>
>>>>
>
> --
> Rune Lillesveen
>
>

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