tree 50ab2c0530f5a7f9e0401248f1486529411499d0
parent 877e91047a351241a8abc6d69b7e593a935dd475
author Frederic Wang <fred.wang@free.fr> 1697090387 +0000
committer moz-wptsync-bot <wptsync@mozilla.com> 1697166874 +0100

[css-properties-values-api] Invalid @property declarations should be dropped.

Currently Firefox properly performs validation of an @property rule, as
defined in [1]. However when such a rule is invalid, it only does not
register the custom property instead of dropping the whole rule. Other
implementations also follow that aproach and existing web platform tests
disagree with the specification [2].

This patch aligns Firefox's behavior with the specification, by moving
@property validation during parsing and dropping invalid rules. Tests
are updated as follows:

1. /css/css-properties-values-api/at-property-cssom.html

  Existing tests that don't have the three descriptors (syntax,
  inherit, initial-value) are invalid and now the test verifies
  no corresponding rules are exposed via CSSOM. `--no-initial-value`
  is renamed `--no-initial-color-value` and its legacy tests are
  kept for a new @property `--no-initial-universal-value` which uses
  the universal syntax (so initial value is optional). Some dummy
  descriptors are added for --tab\ttab so that it remains valid.
  Similarly, we ensure --valid-whitespace's syntax (space-separated)
  and initial-value (comma-separated) agree.

2. /css/css-properties-values-api/at-property.html

  Existing `test_descriptor()` tests are trying an @property with
  a single specified descriptor and so are always invalid. To work
  around that, we tweak `test_descriptor()` so that it can build a
  valid descriptor instead. The `syntax` and `inherits` fallback
  to universal and true respectively while the `initial-value`
  descriptor is built from the `syntax`. An extra parameters is
  introduced in case the caller wants to provide these values
  directly. Finally, when the expected value is null the function
  instead verifies that the rule is really dropped.

  2.1. Some existing syntax tests are registering rules with unquoted
  syntax value 'red', 'rgb(255, 0, 0)', 'color', 'foo | bar' and
  expect to obtain a rule with an empty syntax string, suggesting some
  kind of invalidity handling (cf similar tests). We interpret the
  first two as "specifying a color value", quotes are added and the
  first one actually becomes a valid custom-ident. The last two already
  have a similar quoted version, so we just interpret them as
  "missing quotes".

  2.2. Given the previous 'red' custom-ident, we add tests for invalid
  custom-ident as defined in [3].

  2.3. Some existing `syntax` tests are checking that we must have
  "pipe between components" and no "leading bar" and are again expecting
  a rule with an empty syntax string. We fix the apparent mistake of
  missing quotes and provide initial values that could potentially be
  interpreted as correct by implementations accepting these invalid
  syntaxes.

  2.4. One `initial-value` test is checking "var(--x)" but that is
  not computationally independent so tweak the test to check that
  makes the @property rule invalid. Also add a similar '3em' test
  mentioned in the spec.

  2.5. Some `inherits` tests verify that invalid rules are interpreted
  as false. It seems they should instead be treated as if it does not
  exist and so should make the @property rule invalid.

[1] https://drafts.css-houdini.org/css-properties-values-api-1/#at-property-rule
[2] https://github.com/w3c/css-houdini-drafts/issues/1098
[3] https://drafts.csswg.org/css-values-4/#custom-idents

Differential Revision: https://phabricator.services.mozilla.com/D190444

bugzilla-url: https://bugzilla.mozilla.org/show_bug.cgi?id=1857724
gecko-commit: cfd3a0958f03cb28be6b62a57eb5873358189e1e
gecko-reviewers: emilio