652014 - Add diagnostic for nested at-rules so we give an error when @-moz-keyframes is inside @media

Status: RESOLVED FIXED

(Core :: CSS Parsing and Computation, defect, P3)

Description

[u382751]

User-Agent:       Opera/9.80 (Macintosh; Intel Mac OS X 10.6.6; U; en) Presto/2.8.131 Version/11.50
Build Identifier: 5.0a2

When CSS animations are used outside of media queries they work, but fail when used within a media query

Reproducible: Always

Steps to Reproduce:
1. Click on the link
2. The loader should rotate like http://jsfiddle.net/nimbu/C3rt8/1/
3. Loader fails to rotate
Actual Results:  
No animation

Expected Results:  
The CSS animations get applied.

Comment 1

[Boris Zbarsky [:bzbarsky]]

CSS syntax does not allow nesting @-rules.  So the @-moz-keyframes rule inside @media is ignored.

We should probably report an error to the error console in this situation instead of silently skipping the rule...

Comment 2

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

I think I have a patch for the diagnostic, but the testcase seems to have been modified...

Comment 3

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

Oh, wait, the link in comment 0 is different from the one in the URL field.

Comment 4

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

Attachment: add diagnostic

Comment 5

[Tab Atkins Jr.]

Boris, that doesn't seem right.  According to
<http://www.w3.org/TR/CSS21/syndata.html>, an @-rule can contain more @-rules:

The 'at-rule' construction produces a 'block'.
The 'block' construction can produce the at-rule construction (indirectly).

And section 4.1.5 doesn't appear to give any more specific contraindications.

Comment 6

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

http://www.w3.org/TR/CSS21/grammar.html is very clear that @media rules contain only ruleset.  http://www.w3.org/TR/CSS21/media.html#at-media-rule also says explicitly:
  # At-rules inside @media are invalid in CSS2.1.

Comment 7

[Boris Zbarsky [:bzbarsky]]

Ah, indeed.  The basic CSS2.1 grammar does not disallow nesting @-rules in theory, but it does disallow actually putting @-rules inside any @-rules CSS2.1 defines (that just being @media).

Comment 8

[Boris Zbarsky [:bzbarsky]]

Comment on attachment 527699 [details] [diff] [review]
add diagnostic

r=me

Comment 9

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

https://hg.mozilla.org/mozilla-central/rev/e00435bb54b5