1358586 - Gecko incorrectly accepts -webkit-linear-gradient expressions without a comma after the angle

Status: RESOLVED FIXED

(Core :: CSS Parsing and Computation, enhancement)

Description

[Daniel Holbert [:dholbert]]

We seem to accept -webkit-linear-gradient values with "angle" syntax *without a comma* after the angle.

For example, we honor the following (and paint a gradient in all cases):
data:text/html,<div style="background:-webkit-linear-gradient(135deg red, blue)">Hi

data:text/html,<div style="background:-webkit-linear-gradient(0deg red, blue)">Hi

data:text/html,<div style="background:-webkit-linear-gradient(0 red, blue)">Hi


...but Chrome does not honor those.  If I add a comma after the angle, they do accept it though.

So, we should treat the comma as mandatory here, and we need to update property_database.js accordingly to make http://searchfox.org/mozilla-central/rev/7aa21f3b531ddee90a353215bd86e97d6974e25b/layout/style/test/property_database.js#715 "invalid" instead of "valid" (and add a few similar invalid examples with "deg" units as well).

Comment 1

[Daniel Holbert [:dholbert]]

Attachment: Bug 1358586: Require comma after <angle>, in -webkit-linear-gradient() CSS syntax.

The logic around here is a bit tricky, because -moz-linear-gradient() shares
this codepath. Here's how things were going wrong:

* The -moz-linear-gradient syntax allows an angle (e.g. "30deg") to be followed
  by an optional box-position (e.g. "top right") before eventually requiring a
  comma and then some color stops.
* In contrast, the -webkit-linear-gradient syntax does NOT allow a box-position
  there (unless the box-position is by itself, without an angle).
* So, for -webkit-linear-gradient, we (correctly) skipped the box-position
  parsing code, if we've seen an angle already.
* BUT: in skipping that code, we *also* inadvertantly skipped the code that
  enforces that we eventually see a comma before we get to the color stops.
  So, we incorrectly accept some -webkit-linear-gradient() expressions that are
  missing a comma that really should be mandatory.

So, this patch adds a special case for -webkit-linear-gradient that
preemptively bails if we get an angle that's not followed by a comma. (With
that, we can also simplify the condition around the box position parsing, too.)

Review commit: https://reviewboard.mozilla.org/r/132536/diff/#index_header
See other reviews: https://reviewboard.mozilla.org/r/132536/

Comment 2

[Cameron McCormack (:heycam)]

Comment on attachment 8860545 [details]
Bug 1358586: Require comma after <angle>, in -webkit-linear-gradient() CSS syntax.

https://reviewboard.mozilla.org/r/132536/#review135474

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/a9c09e578cf3
Require comma after <angle>, in -webkit-linear-gradient() CSS syntax. r=heycam

Comment 4

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/a95c42f6d33f
Adjust stylo expectation data a=me

Comment 5

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/69364e8ccec5
Fix adjusted stylo expectation data a=me

Comment 6

[Iris Hsiao [:ihsiao]]

https://hg.mozilla.org/mozilla-central/rev/a9c09e578cf3
https://hg.mozilla.org/mozilla-central/rev/a95c42f6d33f
https://hg.mozilla.org/mozilla-central/rev/69364e8ccec5