1574750 - Add preference to disable MathML length values thinmathspace, mediummathspace, thickmathspace, etc

Status: RESOLVED FIXED

(Core :: MathML, defect)

Description

[Frédéric Wang (:fredw)]

MathML3 defines the following values: https://www.w3.org/TR/MathML3/chapter2.html#type.namedspace

But they are equivalent to em values. The MathML CG agreed to removed them from Core: https://github.com/mathml-refresh/mathml/issues/75#issuecomment-487757558

I think we will need to proceed carefully with these, as we know they are being used https://github.com/mathml-refresh/mathml/issues/55

Comment 1

[Frédéric Wang (:fredw)]

Attachment: Bug 1574750 - Remove support for MathML length values thinmathspace, mediummathspace, thickmathspace, etc. r=emilio

See https://github.com/mathml-refresh/mathml/issues/75
and https://groups.google.com/forum/#!topic/mozilla.dev.platform/yEMdIOo4i-0

This commit introduces a new preference option
mathml.mathspace_names.disabled to disable *mathspace names for MathML lengths.
For now, these are only disabled in Nightly builds.

• test_bug553917.html is updated to check that these values now cause an
  error message to be logged into the console when mathsize names are used
  and the feature disabled.
• mathml-negativespace-ref.html and positive-namedspace.html verify support for
  mathspace names, so force running them with the support enabled.
• The reference files for mo-lspace-rspace-2.html, mo-lspace-rspace-3.html,
  mo-lspace-rspace.html, op-dict-8.html and op-dict-9.html use explicit
  lspace/rspace attributes corresponding to the one read from the operator
  dictionary. Instead of running them with mathspace names enabled, use the
  equivalent em values from core
  https://mathml-refresh.github.io/mathml-core/#operator-dictionary
  See https://github.com/mathml-refresh/mathml/issues/75#issuecomment-523016332
• Force WPT tests
  mathml/presentation-markup/fractions/frac-linethickness-002.html and
  mathml/relations/css-styling/lengths-2.html to be run with the features
  disabled and remove corresponding failure expectation.

Comment 2

[Frédéric Wang (:fredw)]

https://treeherder.mozilla.org/#/jobs?repo=try&revision=6ea0bc9a51b456ef03b9d55bc0841464ba6cb1fc

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/fc9ada7ccc21
Remove support for MathML length values thinmathspace, mediummathspace, thickmathspace, etc. r=emilio

Comment 4

[Frédéric Wang (:fredw)]

For the dev doc, here are the substitutions to perform:
https://github.com/mathml-refresh/mathml/issues/75#issuecomment-523016332

Comment 5

[Andrei Ciure[:aciure]]

https://hg.mozilla.org/mozilla-central/rev/fc9ada7ccc21

Comment 6

[Kohei Yoshino [:kohei]]

Posted site compatibility note: https://www.fxsitecompat.dev/en-CA/docs/2019/various-legacy-mathml-features-have-been-deprecated-or-removed/

Comment 7

[Florian Scholz (Open Web Docs)]

I don't think these length values appear in the MathML reference documentation other than here: https://developer.mozilla.org/en-US/docs/Web/MathML/Attribute/Values#Constants I've updated that section.

Please add 'dev-doc-needed' to the bug that removes this in a stable Firefox version.

Comment 8

[Tom Ritter [:tjr] (OOTO until 4/30 at least)]

Emilio, do you know if we can disable these on release at this point?

Comment 9

[Frédéric Wang (:fredw)]

This was not handled by https://bugzilla.mozilla.org/show_bug.cgi?id=1772697 yet. I guess we need to analyze usage and try to disable it.