On Tue, Feb 26, 2019 at 08:56:05PM -0800, Matt Kline wrote:
With that said, I respectfully point out that "--- gives an em dash" is prescribed in almost every TeX and LaTeX reference you can find, including Knuth's TeXbook, Lamport's LaTeX: ADPS, and popular online guides. A change like this is sure to cause a mismatch in expectations for most folks: anybody who doesn't actively follow TeX development on the mailing lists (which I presume is most users) will likely be surprised and frustrated that this decades-old convention suddenly stops working after recent updates.
They are implemented as ligatures in Computer Modern fonts, so it is not unreasonable for them to not work with any other font that does not have such ligatures. XeTeX and LuaTeX providing ways to emulate this with other fonts is already going out of their way, since even Knuth's TeX does not do this (if the font does not have a ligature it will do nothing). Regards, Khaled