[bug #60571] Footnote markers defeat end-of-sentence recognition

[G. Branden Robinson]

URL:
  <https://savannah.gnu.org/bugs/?60571>

                 Summary: Footnote markers defeat end-of-sentence recognition
                 Project: GNU troff
            Submitted by: gbranden
            Submitted on: Mon 10 May 2021 02:55:16 PM UTC
                Category: Core
                Severity: 3 - Normal
              Item Group: Incorrect behaviour
                  Status: None
                 Privacy: Public
             Assigned to: None
             Open/Closed: Open
         Discussion Lock: Any
         Planned Release: None

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Details:

I see the following in ms.ms.


The ms macros are the oldest surviving package for roff systems.[1] While the 
man  package
...
    Longer  documents  include a table of contents, which you can invoke by
placing the .TC
    macro at the end of your document.[2] Printing the table of contents at
the end is nec‐
...
On  occasion,  you  may want to keep multiple lines of text together on the
same page.  For
example, ms enables you to prevent a page break between two paragraphs, or
between a  para‐
graph and an adjacent list, table, or other item it discusses.[3] Material
thus grouped  is


I am ending my input lines after the footnote marker, but by having characters
that don't have the .cflags option set after my end-of-sentence punctuation,
detection of the end of the sentence is defeated.

The macro package user shouldn't have to care about this, but in any case
there doesn't seem to be a mechanism to work around it.  There is no escape
sequence that enables us to bracket a sequence of input characters as
transparent to end-of-sentence detection.

Manipulating the .cflags of numerals inside the * string definition is not
syntactically possible.  (How would I do this with .ds?)  And we don't want
the macro package set the .cflags for the numerals in a more general case
because that would just be wrong.  Consider this sentence.


I'm spitballing here; in other words, it's just my .02
bucks.


Making the numerals transparent would create a false positive end-of-sentence
detection after "my .".

I'm thinking we need yet another read-only register exposing internal troff
state, that being the end of sentence detection flag.  We could call it .eos
maybe.  It could be saved before the footnote marker is written, then restored
afterwards.  But that would still mean turning ms's * from a string into a
macro.  Hmm.

Maybe someone else has a better idea.




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