[Dev-luatex] Re: Ignore null paragraph before display equation

On 2/2/2025 12:52 PM, Udicoudco wrote:

Hello Hans,

On Sun, Feb 2, 2025 at 1:35 PM Hans Hagen wrote:

...

This kind of behavior is not going to change .. adding / changing things wrt luatex waS frozen for a reason so only real bugs get fixed.

Then why was it changed *after* LuaTeX was declared as frozen (LuaTeX 1.10) for paragraphs not created by math displays?

well, 1.10 was kind of an official release where we decided that this-is-it also because of pressure to freeze (before that we only had sort of stable development snapshots for TL) but realy freezing happened bit later with it now being deep-freeze

(It was you who changed it :)

indeed kind of a bug

To me, it seems like it was decided it is a bug... and simply display math was not considered at the time.

because displaymmath is used in various scenarios: as a pargaraph of its own, inside a paragraph (where it is assumed to take 3 lines), in order to catch a previous line width (kind of an abuse), etc we also don't remove dir nodes from hboxes when there's only dirs (so \ifvoid is seeing them)

...

Keep in mind that there a lot of macro code around thta depends on the engine not changing.

This is why I suggested to add a new possible value to one of the *mode primitives, if you think this is a breaking change (although it was not done three years ago)

indeed something like that has to be under mode primitive control; for an empty paragraph one can argue that the textdir is a side effect but for a construct like display math it's a bit different, so maybe mode control is indeed needed here (\mathemptydisplaymode) as we can't know if it won't break something where it is assumed so can you add a mode ? (i have no time for doing that now) Hans ----------------------------------------------------------------- Hans Hagen | PRAGMA ADE Ridderstraat 27 | 8061 GH Hasselt | The Netherlands tel: 038 477 53 69 | www.pragma-ade.nl | www.pragma-pod.nl -----------------------------------------------------------------