Re: How do I set up font fallback in a robust way?

[Eli Zaretskii <eliz@gnu.org>]

> From: Clément Pit--Claudel <clement.pit@gmail.com>
> Date: Sat, 9 Apr 2016 15:14:50 -0400
> 
> Since my main programming font does not cover all the mathematical symbols I need, I initially set up font fallback as shown below:
> 
>     (set-fontset-font t 'unicode (font-spec :name "FreeMono") nil 'append)
>     (set-fontset-font t 'unicode (font-spec :name "Symbola") nil 'append)

The default fontset already defines specific blocks to be handled by
these fonts, see fontset.el.  What problems, specifically, do you have
with the default setup and the current emacs-25 branch?

> What's the proper way to configure font fallback?

In general: find the characters you want to change and augment the
default fontset to use the font you want for them.

But let's first see the specific problems you have with the Emacs 25
defaults.  This issue got some attention a few months ago, so I'm
surprised to hear there are still problems in that area.

> *Note*: for testing purposes, here are a few math characters: `ℕ𝓟⧺×≠≥≤±¬∨∧∃∀λ⟿⟹⊥⊤⊢`

Which, if any, of those give you trouble with the default fontset?