Currently, NAC always inherits from the closest non-NAC ancestor element,
regardless of whether it is for an element-backed pseudo or not.
This patch changes the inheritance so that for element-backed pseudos, we
inherit from the closest native anonymous root's parent, and for other NAC we
inherit from the parent.
This prevents the following two issues and allows us to remove the
NODE_IS_NATIVE_ANONYMOUS flag:
* Avoiding inheriting from the non-NAC ancestor in XBL bindings bound to NAC.
- This is no longer a problem since we apply the rule only if we're a
pseudo-element, and all pseudo-elements are in native anonymous subtrees.
- This also allows to remove the hack that propagates the
NODE_IS_NATIVE_ANONYMOUS flag from the ::cue pseudo-element from
BindToTree.
* Inheriting from the wrong thing if we're a nested NAC subtree.
- We no longer look past our NAC subtree, with the exception of
::-moz-number-text's pseudo-elements, for which we do want to propagate
::placeholder to.
A few rules from forms.css have been modified because they're useless or needed
to propagate stuff to the anonymous form control in input[type="number"] which
previously inherited from the input itself.
Bug: 1460382
Reviewed-by: heycam
MozReview-Commit-ID: IDKYt3EJtSH
Now that we have an Element around on cascade, we can stop using the cascade
flags mechanism to pass various element-related state, like "is this element the
root", or "should it use the item-based display fixup".
That fixes handwaviness in the handling of those flags from style reparenting,
and code duplication to handle tricky stuff like :visited.
There are a number of other changes that are worth noticing:
* skip_root_and_item_based_display_fixup is renamed to skip_item_display_fixup:
TElement::is_root() already implies being the document element, which by
definition is not native anonymous and not a pseudo-element.
Thus, you never get fixed-up if your NAC or a pseudo, which is what the code
tried to avoid, so the only fixup with a point is the item one, which is
necessary.
* The pseudo-element probing code was refactored to return early a
Option::<CascadeInputs>::None, which is nicer than what it was doing.
* The visited_links_enabled check has moved to selector-matching time. The rest
of the checks aren't based on whether the element is a link, or are properly
guarded by parent_style.visited_style().is_some() or visited_rules.is_some().
Thus you can transitively infer that no element will end up with a :visited
style, not even from style reparenting.
Anyway, the underlying reason why I want the element in StyleAdjuster is because
we're going to implement an adjustment in there depending on the tag of the
element (converting display: contents to display: none depending on the tag), so
computing that information eagerly, including a hash lookup, wouldn't be nice.
Not super-proud of this one, but it's the easiest way I could think of.
The changeset looks bigger than what it is, because while at it I've rewrapped a
fair amount of functions around to use proper block indentation.
Alternatives are parameterizing Stylist by <E>, which is not fun, or moving the
concrete element from layout_thread to layout, but that implies layout depending
on script, which isn't fun either.
Other alternative is implementing an empty enum and making anon boxes work on
it. It has the advantage of removing the annoying type parameter, but the
disadvantage of instantiating `cascade` twice, which isn't great, and having to
maintain all the boilerplate of a `TElement` implementation that just does
nothing.
All TElement's implement Copy, and are just pointers, so the double indirection
is stupid.
I'm going to try to see if removing this double-indirection fixes some
selector-matching performance, and this is a trivial pre-requisite while I wait
for Talos results.
This reverts commit 1970e82b0d, reversing
changes made to e882660ea6.
The reparenting logic is still bogus, but I'll figure out how to deal with that
in a bit.
In practice the only NAC that possibly inherits from a grid or flex container
are pseudos.
In Gecko, if the root element is an item container, custom anon content would
also sometimes incorrectly inherit from that (see bug 1405635), but that's fixed
in Stylo.
We remove the IS_ROOT_ELEMENT blockification from the "skip display fixup"
check, since the root element is never NAC or anything like that, so there's no
need for the check.
This also fixes some reparenting fishiness related to pseudo-elements. We were
only skipping the fixup when reparenting anon boxes, not when reparenting normal
element styles, nor when reparenting other pseudo styles which are not anon
boxes.
Right now we go through a lot of hoops to see if we ever see a relevant link.
However, that information is not needed: if the element is a link, we'll always
need to compute its visited style because its its own relevant link.
If the element inherits from a link, we need to also compute the visited style
anyway.
So the "has a relevant link been found" is pretty useless when we know what are
we inheriting from.
The branches at the beginning of matches_complex_selector_internal were
affecting performance, and there are no good reasons to keep them.
I've verified that this passes all the visited tests in mozilla central, and
that the test-cases too-flaky to be landed still pass.
We have optimizations to avoid doing selector-matching when the style attribute
changes, so, given you can toggle the display property and the pseudo-elements
will suddenly become effective, we can't really skip them.
Furthermore, we assume that if an element has an ElementStyles, they're
up-to-date and we can use them for getComputedStyle, so it's pretty easy to
prove that we do the wrong thing when calling getComputedStyle with a
pseudo-element on a display: none root.
Bug: 1384065
Reviewed-by: heycam
MozReview-Commit-ID: BIOqevGZyrm
The alias is left there temporarilly and will be removed completely in a later commit where
also components/style/gecko/generated/structs_{debug|release}.rs are re-generated (they still
use the old alias).
