Commits on Oct 10, 2023

1. Silence "warning: cannot select font 'C'" with GNU roff 1.23 …

   It's difficult to portably ask the man(7) macro package for a monospaced
   font (whether it's referred to as C, CW or CR) without any extra
   configuration.  That's what leads to:
     warning: cannot select font 'C'
   
   This can be reproduced on Fedora 39, which has GNU roff 1.23, with:
     $ man crun >/dev/null
     troff:<standard input>:25: warning: cannot select font 'C'
     troff:<standard input>:134: warning: cannot select font 'C'
     ...
     $ man podman >/dev/null
     troff:<standard input>:15: warning: cannot select font 'C'
     troff:<standard input>:25: warning: cannot select font 'C'
     ...
     $ man toolbox >/dev/null
     troff:<standard input>:33: warning: cannot select font 'C'
     troff:<standard input>:43: warning: cannot select font 'C'
     ...
   
   These may look like odd uses of man(1), but it's used by the Toolbx [1]
   test suite to ensure that 'toolbox help' and 'toolbox --help' do render
   the toolbox(1) manual, which, like crun(1) and podman(1), is generated
   by go-md2man(1).
   
   The warnings come from the current \\fB\\fC sequence for inline code
   enclosed in single backticks (ie., `) that uses 'C' to ask for a
   monospace font.  Other than the difficulties with portably asking the
   man(7) macro package for a monospace font, the \\fB\\fC sequence has
   some oddities.
   
   If a monospace font does get selected by \\fC, then the request for bold
   with \\fB gets masked, with the possible surprise that switching back to
   the 'previous font' with \\fP will result in bold.  This is what happens
   when the manual is rendered in HyperText Markup Language or PostScript:
     $ man --troff-device html <manual> > foo.html
     $ man --troff-device ps <manual> > foo.ps
   
   If the manual is displayed on a terminal device, \\fC is a NOP because
   terminals are always monospaced and can't change the font family.  So,
   only \\fB is in effect.
   
   Therefore, the use of \\fC is only relevant for non-terminal outputs,
   like HTML and PS.  Since HTML and PS use serif fonts by default, an
   inline switch to monospace looks visually jarring.  This is different
   from other common uses of monospace for inline code, such as on GitLab
   and GitHub, where sans-serif fonts are used by default.
   
   Hence, just don't attempt to use monospace for inline code enclosed in
   single backticks (ie., `) and stick to bold everywhere.
   
   As suggested by G. Branden Robinson.
   
   [1] https://containertoolbx.org/
       https://github.com/containers/toolbox
   
   cpuguy83#99
   https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1049968

   

   debarshiray committed Oct 10, 2023
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