Test - - http://w3c-test.org/css/vendor-imports/mozilla/mozilla-central-reftests/contain/contain-layout-formatting-context-margin-001.html https://dxr.mozilla.org/mozilla-central/source/layout/reftests/w3c-css/submitted/contain/contain-layout-formatting-context-margin-001.html Reference file - - - - - - - http://w3c-test.org/css/vendor-imports/mozilla/mozilla-central-reftests/contain/contain-paint-formatting-context-margin-001-ref.html https://dxr.mozilla.org/mozilla-central/source/layout/reftests/w3c-css/submitted/contain/contain-layout-formatting-context-margin-001-ref.html Explanations - - - - - - #c (the light blue sliver) overflows #a which has 'contain: layout'. "If the contents of the element overflow the element, they must be treated as ink overflow." So, the light blue sliver should be rendered and not be clipped. Actual ------ The light blue sliver is absent in the reference file. Expected -------- The light blue sliver is present in the reference file. Credit should go to Manuel Rego Casasnovas for reporting this.

I think you meant for this to be about "contain-layout-formatting-context-margin-001.html", not any contain-paint-* files, correct? (The bug title and one of the URLs in comment 0 have "contain-paint-*" filenames, but the other 3 URLs in comment 0 have "contain-layout-*" filenames) --> Fixing bug title, assuming I'm understanding correctly.

Oh, I see -- contain-layout-formatting-context-margin-001.html does have <link rel="match" href="contain-paint-formatting-context-margin-001-ref.html"> i.e. it's incorrectly pointing to a contain-paint reference case, rather than to its own correspondingly-named reference case. Maybe that's the issue you're reporting here? That does indeed seem to be a typo that needs fixing.

Hm... Daniel, you indeed untangled something that I did not untangled correctly in the first place. Yes, the <link rel="match">'s href in the test incorrect.

Pushed by dholbert@mozilla.com: https://hg.mozilla.org/integration/mozilla-inbound/rev/609607ebb73e Fix typo in reference case link-tag for reftest contain-layout-formatting-context-margin-001.html. (no review; just a trivial test metadata tweak)

Thanks for reporting this. I've landed a fix, which I think should make it upstream to WPT within a day or two.

web-platform-tests import in https://github.com/web-platform-tests/wpt/pull/12954