bug#58184: Faulty font selection for Latin characters

[Eli Zaretskii]

> From: समीर सिंह Sameer Singh
>  <lumarzeli30@gmail.com>
> Date: Fri, 30 Sep 2022 04:23:28 +0530
> 
> When a font is set for the "default" face in the init.el file.
> For example, like this:
> 
> (set-face-attribute 'default nil
>    :font "Fira Code"
>    :weight 'regular
>    :height 170)
> 
> This messes up the font selection for various latin and all ipa characters.

What happens if you use 'medium instead of 'regular?

> Despite the configured font supporting the characters which are typed, Emacs 
> selects a different font for
> them, this results in visually jarring text or sometimes failed composition.
> 
> For example see in 1.png
> All of the letters except ṇ (#x1E47) are in Fira Code while it is in Latin 
> Modern Mono despite Fira Code
> supporting it.
> Below it t̪ (t + #x32A) is not composed properly because while 't' is in 
> FiraCode #x32A is in Step Regular.
> 
> Note: This does not happen with emacs -Q

I don't understand: what doesn't happen in "emacs -Q"?  Can you show a
recipe starting from "emacs -Q" that reproduces the problem?