The block overflow ellipsis generated by block-ellipsis (one of the longhands for line-clamp) can fully displace a line box's entire contents, so the line would only contain that ellipsis. While the ellipsis behaves as if it had line-height: 0, when it fully displaces a line, it is considered to contain a "strut", so the line doesn't end up having a height of zero (unless the block container also had line-height: 0).
However, in quirks mode, the "blocks ignore line-height quirk" has the effect of removing the strut corresponding to the root inline box, and the "line height calculation quirk" has the effect of removing struts from any other inline boxes (except that line-left and line-right paddings and borders behave as non-removed struts).
These quirks together have the effect that the height of a line box is not floored by the line-height of any inline box, including the root inline box, unless that inline has glyphs.
Given that, how should those quirks interact with the block overflow ellipsis? Since it explicitly behaves like an inline with line-height: 0, maybe these quirks should prevent that strut. Otherwise we'd have an ellipsis which would otherwise not contribute to a line box's layout bounds, contribute to them if it's the only thing in the line.
The block overflow ellipsis generated by
block-ellipsis(one of the longhands forline-clamp) can fully displace a line box's entire contents, so the line would only contain that ellipsis. While the ellipsis behaves as if it hadline-height: 0, when it fully displaces a line, it is considered to contain a "strut", so the line doesn't end up having a height of zero (unless the block container also hadline-height: 0).However, in quirks mode, the "blocks ignore line-height quirk" has the effect of removing the strut corresponding to the root inline box, and the "line height calculation quirk" has the effect of removing struts from any other inline boxes (except that line-left and line-right paddings and borders behave as non-removed struts).
These quirks together have the effect that the height of a line box is not floored by the
line-heightof any inline box, including the root inline box, unless that inline has glyphs.Given that, how should those quirks interact with the block overflow ellipsis? Since it explicitly behaves like an inline with
line-height: 0, maybe these quirks should prevent that strut. Otherwise we'd have an ellipsis which would otherwise not contribute to a line box's layout bounds, contribute to them if it's the only thing in the line.