Dear Maintainer,

   * What led up to the situation?

     Checking for defects with

[test-][g|n]roff -mandoc -t -K utf8 -ww -b -z <man page>

  [test-groff is a script in the repository for "groff"]

   * What was the outcome of this action?

troff: backtrace: '/home/bg/git/groff/build/s-tmac/an.tmac':562: macro 'B'
troff: backtrace: file '<stdin>':117
troff:<stdin>:117: warning: ignoring escape character before '+'
troff: backtrace: '/home/bg/git/groff/build/s-tmac/an.tmac':562: macro 'B'
troff: backtrace: file '<stdin>':174
troff:<stdin>:174: warning: cannot select font 'F'
troff: backtrace: file '<stdin>':534
troff:<stdin>:534: warning: [page 6, 9.1i]: cannot break line

   * What outcome did you expect instead?

     No output (warnings).

-.-

  Remarks and a patch are in the attachments.

I have included portions of this in the upstream MR:
https://gitlab.freedesktop.org/xorg/xserver/-/merge_requests/1875

The first line too long fix cannot be applied upstream as the upstream source
substitutes the font path at build time, so it doesn't appear expanded
as it does in this patch.

The second line too long issue was already handled by a previous commit in
this MR.