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[css-grid] grid-line custom identifier auto? #2856
Description
Blink and WebKit reject grid-row-end 1 auto.
Edge and Firefox accept grid-row-end 1 auto and serialize it as 1 auto.
Blink and WebKit reject grid-row-end values span 1 auto, span auto 1 and 1 auto span.
Edge and Firefox accept these and serialize all of them as span 1 auto.
Testing with uppercase makes it clear that span is being accepted as a keyword and auto is being accepted as a custom identifier:
http://jsfiddle.net/ericwilligers/meya2q7d/
All browsers reject the following:
auto 1
span span 1, span 1 span and 1 span span
1 span auto, auto 1 span and auto span 1
The relevant grammar for <grid-line> is
<grid-line> =
auto |
<custom-ident> |
[ <integer> && <custom-ident>? ] |
[ span && [ <integer> || <custom-ident> ] ]
Are auto or span permitted as a <custom-ident>?
The custom-ident spec may be relevant:
Note: When designing grammars with
<custom-ident>, the<custom-ident>should always be "positionally unambiguous", so that it’s impossible to conflict with any keyword values in the property.
I don't see a reading of the spec where span 1 auto would be permissible but not span 1 span.
Activity
mrego commentedon Jul 2, 2018
Some excerpts from Grid Layout spec:
Also from CSS Values and Units spec:
There is also a related issue #494 and some old threads in www-style:
[css-grid] Parse various grid properties
fantasai commentedon Jul 24, 2018
Seems to me the spec is clear that
spanisn't valid as a<custom-ident>. But it does raise the question of whetherautoshould be similarly excluded.css-meeting-bot commentedon Aug 8, 2018
The Working Group just discussed
grid-line custom identifier auto?, and agreed to the following:RESOLVED: drop auto from grid line syntaxThe full IRC log of that discussion
<dael> Topic: grid-line custom identifier auto?<dael> github: https://github.com//issues/2856
<dael> Rossen_: eric brought this and fantasai you put this on the agenda
<dael> fantasai: There was an issue against grid asking if the ID auto should be excluded from the places where we use custom ident to rep. named lined. Auto has a special meaning it doesn't resolve to a named line. We exclude span keyword, but not auto.
<dael> fantasai: Question if we should exclude auto in places we exclude span
<dael> Rossen_: I wouldn't put span and auto in same cat. for this behavior. span is forward looking directive and auto is a applied to a single item
<dael> fantasai: You cannot have...if you named a line auto you're just going to have trouble, esp. in level 2 where you can combine auto with a custom ident. You can see the grammar in the issue. If a custom ident can include auto you can write auto1 and have that resolve. I'm not sure allowing that is helpful
<dael> fantasai: Where we have span custom ident we're planning to add auto as a similar pattern. That's a grid 2 issue
<fantasai> https://github.com//issues/796#issuecomment-385547068
<dael> Rossen_: I see your point
<dael> Rossen_: I can live with it
<dael> Rossen_: Anyone from mozilla that's close to grid impl. dbaron do you have an opinion?
<dael> dbaron: No opinion. Have to ask Mats
<dael> Rossen_: It's only our impl that allow auto
<dael> fantasai: I think chances of people naming a line auto is pretty much 0 unless you're a QA person
<dael> Rossen_: How did we end up removing span but not auto?
<dael> fantasai: Don't know. I think there's some syntactic construct where one was ambig. It said span and a custom ident you could do and you want to know that you are consuming a custom ident or the span up front. If you write span span is it a keyword or an ident. So we prob did for parsing
<dael> Rossen_: We allow span int and span custom ident
<dael> fantasai: Yes and auto custom ident will be in L2
<dael> Rossen_: Okay, I'm okay with proposed change
<dael> Rossen_: Any other opinions? Or do we try to resolve?
<fantasai> s/auto custom ident/auto <custom-ident>/
<dael> Rossen_: Objections to dropping auto from grid line syntax?
<dael> RESOLVED: drop auto from grid line syntax
[css-grid] Exclude 'auto' from line name
[css-grid] Parse various grid properties
[css-grid] Exclude 'auto' from line name
[css-grid] Parse various grid properties
Bug 1502185 - Don't allow auto in grid line names. r=mats
Bug 1502185 - Don't allow auto in grid line names. r=mats
Bug 1502185 - Don't allow auto in grid line names. r=mats
style: Don't allow auto in grid line names.
Bug 1502185 - Don't allow auto in grid line names. r=mats
Bug 1502185 - Don't allow auto in grid line names. r=mats
Bug 1502185 - Don't allow auto in grid line names. r=mats
Bug 1502185 - Don't allow auto in grid line names. r=mats