Re: being clearer about css-wide keywords and reset-only sub-properties [css-cascade][css-grid][css-border]

On Saturday 2015-11-28 17:21 -0800, Tab Atkins Jr. wrote:
> On Tue, Nov 17, 2015 at 7:51 AM, L. David Baron <dbaron@dbaron.org> wrote:
> > I think this points to lack of clarity in the spec wording, given
> > that the definition I quote above in css-cascade is not findable
> > from the definitions of these reset-only sub-properties.  I think
> > that the prose defining these reset-only sub-properties in css-grid,
> > css-border, etc., should:
> >
> >   1. link to the definition of the term "reset-only sub-property" in
> >      css-cascade
> >
> >   2. either (a) be more deferential to that definition about what it
> >      means (and not state that the properties are reset to initial
> >      values) or (b) explicitly mention that CSS-wide keywords are
> >      applied rather than resetting those subproperties to their
> >      initial values (as all other values of the shorthand do).  Or,
> >      to put it another way, spec prose should not state that most
> >      values reset the subproperty to its initial value without also
> >      stating that the css-wide keywords do otherwise.
> 
> The css-wide keywords are never present in the grammars, and thus
> never described in the definitions of the property.  They're defined
> for all properties in Cascade in a uniform manner - they get expanded
> out to themselves for all subproperties. I don't really want to have
> to remember to include boilerplate in the description of every
> shorthand reminding people that the css-wide keywords exist and how
> they work; that's extra work, and provokes extra confusion when it's
> forgotten and people try to infer a difference from the lack.

I'm not saying that something needs to be done for every shorthand.
I'm saying that it needs to be done when properties are defined as
reset-only subproperties.

Lax wording defining reset-only subproperties has been taken to
trump the general rules by multiple implementors who work on
different engines:
  https://code.google.com/p/chromium/issues/detail?id=557159#c5
  https://bugzilla.mozilla.org/show_bug.cgi?id=1176792#c40 (and #c39)
so this is in fact a real problem.

-David

-- 
𝄞   L. David Baron                         http://dbaron.org/   𝄂
𝄢   Mozilla                          https://www.mozilla.org/   𝄂
             Before I built a wall I'd ask to know
             What I was walling in or walling out,
             And to whom I was like to give offense.
               - Robert Frost, Mending Wall (1914)