URL: <https://savannah.gnu.org/bugs/?67356>
Summary: Make "semantic" tty-char.tmac fallbacks more widely
available
Group: GNU roff
Submitter: barx
Submitted: Fri 25 Jul 2025 04:54:51 PM CDT
Category: Macro package - others/general
Severity: 1 - Wish
Item Group: Feature change
Status: None
Privacy: Public
Assigned to: None
Open/Closed: Open
Discussion Lock: Any
Planned Release: None
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Follow-up Comments:
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Date: Fri 25 Jul 2025 04:54:51 PM CDT By: Dave <barx>
Branden wrote in bug #67252 that some of the
[http://git.savannah.gnu.org/cgit/groff.git/tree/tmac/tty-char.tmac
tmac/tty-char.tmac] fallbacks are "suitable any time your device's fonts don't
have coverage." In particular, the ones he terms "semantic" fallbacks (e.g.,
"<infinity>" for \[if]) communicate useful information if the specified glyphs
are unavailable, regardless of whether or not output is to a terminal (tty).
However:
* The only place tty-char.tmac is loaded automatically is from nroff.sh.
* The only place tty-char.tmac is documented is in comments in itself and in
tty.tmac (and even there, suboptimally: bug #62814). (See also bug #61958.)
* Fallbacks in tty-char.tmac are defined using ".if !cA .char A B" logic.
Testing the character's existence once and then overriding it globally is
suitable for a terminal device, where a glyph is either available or not on
that device. It is not suitable for a typesetter device, where fonts can
change, and glyphs available in some fonts might not be in others.
* As Branden notes in #67252, there's no clean way to separate the "semantic"
fallbacks from the others; users would have to manually copy the ones they
want, or edit tty-char.tmac.
So the current infrastructure effectively supports tty-char.tmac fallbacks
only when running nroff. This ticket requests making the semantic ones more
widely available.
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