LGTM2
On 04/10/2023 11:49, Yoav Weiss wrote:
Thanks for clarifying and verifying! :) My LGTM still stands.
On Wed, Oct 4, 2023 at 11:48 AM Anders Hartvoll Ruud
<andr...@chromium.org <mailto:andr...@chromium.org>> wrote:
On Tue, Oct 3, 2023 at 8:46 PM Anders Hartvoll Ruud
<andr...@chromium.org <mailto:andr...@chromium.org>> wrote:
On Tue, Oct 3, 2023 at 3:14 PM Yoav Weiss
<yoavwe...@chromium.org <mailto:yoavwe...@chromium.org>> wrote:
LGTM1
Thanks for evaluating the compat risk for this. While
non-zero, it seems manageable given Mozilla already shipping
this, with Safari likely to follow, given the landed
implementation.
Clarification: Mozilla is shipping the main part of the feature
(retrying a failed declaration as a nested style rule), but they
are not (yet) shipping the tweaks to css-syntax described as
risk (1) and (2). (1) is a recent resolution (~three weeks), so
no mystery there. (2) has been part of this all along - I assume
it was seen as something that could be done separately (and it is).
Just to make sure it wasn't /deliberately/ omitted for whatever
reason, I checked with Emilio and they do intend to implement (1)
and (2) once it's specified.
So in this case "Mozilla: Shipping" should only be interpreted
as a positive signal for the overall change, not as a way to
manage compat risk. :-)
I'll emphasize again though, that in both (1) and (2), we're
just changing from one kind of invalid/has-no-effect to a
/slightly/ different kind of invalid/has-no-effect.
On Mon, Oct 2, 2023 at 1:30 PM Anders Hartvoll Ruud
<andr...@chromium.org <mailto:andr...@chromium.org>> wrote:
Contact emails
andr...@chromium.org <mailto:andr...@chromium.org>
Specification
https://drafts.csswg.org/css-syntax/#consume-block-contents
<https://drafts.csswg.org/css-syntax/#consume-block-contents>
Summary
Allows nested style rules
<https://drafts.csswg.org/css-nesting-1/#nested-style-rule> to
begin with an identifier. For example, the following will now be possible:
p {
span { color: green; }
}
<p>
<span>I am green</span>
</p>
Before this change, the inner spanselector had to be
“escaped” using :is()or similar, due to restrictions in
css-syntax. These restrictions have now been lifted by
giving the parser the ability to restart
<https://drafts.csswg.org/css-syntax/#token-stream-restore-a-mark>.
Blink component
Blink>CSS
<https://bugs.chromium.org/p/chromium/issues/list?q=component:Blink%3ECSS>
TAG review
None
TAG review status
Not applicable
Risks
Interoperability and Compatibility
To address some problematic parsing edge cases, the
CSSWG has made two additional changes to css-syntax that
have theoretical web-facing impact. These changes will
ship in this intent as well:
1.
Braces ({}) are now fundamentally invalid in
standard properties, unless they span the whole
value. No property grammar allows {}in any part of
the value currently, so this is already invalid, but
when var()is used in combination with {}, this
intent changes whenit becomes invalid. With this
intent, e.g. color: var(--x) {};becomes invalid
parse-timeinstead of at computed-value time
<https://drafts.csswg.org/css-variables/#invalid-at-computed-value-time>. This isan
observable difference, but there’s no known reason for this to occur in practice outside of
mistakes. Nevertheless, I have tried to estimate the number of possibly-impacted sites: ~0.0011%
(Web Compat Analysis: Relaxed Nesting
<https://docs.google.com/document/d/1WxIAXWFy3q9XJrFK8k2J5my71jn8Cvdxq6Z8NAg99Q0/edit#bookmark=id.ufp2erlyto93>[@chromium.org
<http://chromium.org>]).
2.
A style rule prelude (i.e. the selector list) can no
longer start with --ident:. Again, this is in a
sense already “invalid”, since HTML elements never
start with -- (including custom elements, which must
start with a letter), so such rules can never match
anything. This intent makes the situation a parse
error instead. Estimated impact: ~0.0007% (Web
Compat Analysis: Relaxed Nesting
<https://docs.google.com/document/d/1WxIAXWFy3q9XJrFK8k2J5my71jn8Cvdxq6Z8NAg99Q0/edit#bookmark=id.geo17wxm8bwh>[@chromium.org
<http://chromium.org>]).
Gecko: Shipped/Shipping
(https://www.mozilla.org/en-US/firefox/117.0/releasenotes
<https://www.mozilla.org/en-US/firefox/117.0/releasenotes>)
WebKit: In development
(https://github.com/WebKit/WebKit/pull/17189
<https://github.com/WebKit/WebKit/pull/17189>)
Web developers: No signals
Other signals:
WebView application risks
Does this intent deprecate or change behavior of
existing APIs, such that it has potentially high risk
for Android WebView-based applications?
None
Debuggability
Nested style rules that start with identifiers appear in
the inspector like other nested style rules.
Will this feature be supported on all six Blink
platforms (Windows, Mac, Linux, Chrome OS,
Android, and Android WebView)?
Yes
Is this feature fully tested by
web-platform-tests
<https://chromium.googlesource.com/chromium/src/+/main/docs/testing/web_platform_tests.md>?
Yes
The tests exist in wpt_internal/css/css-nesting/ident at
the time of writing, but will be upstreamed when the
feature is turned on.
Flag name on chrome://flags
CSSNestingIdent
Finch feature name
I’m not sure what a “Finch feature name” is. There have
been no Finch trialsrelated to this, but the feature is
guarded by the Blink runtime flag “CSSNestingIdent” with
“base_feature” unset, which automatically generates a
corresponding base::Feature.
Non-finch justification
None
Requires code in //chrome?
False
Estimated milestones
Shipping on desktop
120
Shipping on Android
120
Shipping on WebView
120
Anticipated spec changes
These issues need to be resolved and/or edited into the
spec beforeshipping.
*
https://github.com/w3c/csswg-drafts/issues/9317
<https://github.com/w3c/csswg-drafts/issues/9317>The
behavior that braces are invalid in standard
properties (unless it’s the whole value) was
resolved at TPAC 2023, but css-syntax has not been
updated yet.
*
https://github.com/w3c/csswg-drafts/issues/9336
<https://github.com/w3c/csswg-drafts/issues/9336>This is a
tweak to the error recovery of the --ident: case. This needs a resolution, and an
edit.
There are no anticipated spec changes aftershipping.
Link to entry on the Chrome Platform Status
https://chromestatus.com/feature/5070369895743488
<https://chromestatus.com/feature/5070369895743488>
This intent message was generated by Chrome Platform
Status <https://chromestatus.com/>.
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