[bug #64255] [eqn] "big" is broken

[G. Branden Robinson]

URL:
  <https://savannah.gnu.org/bugs/?64255>

                 Summary: [eqn] "big" is broken
                   Group: GNU roff
               Submitter: gbranden
               Submitted: Fri 26 May 2023 07:24:08 AM UTC
                Category: Preprocessor eqn
                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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Follow-up Comments:


-------------------------------------------------------
Date: Fri 26 May 2023 07:24:08 AM UTC By: G. Branden Robinson <gbranden>
Affects groff 1.22.4.  Appears to go all the way back to this feature's
introduction in commit d239103a7b, 3 February 2007.

"big" is documented as a primitive, but it doesn't work that way.  Instead it
is contextually meaningful only after a "size" primitive.

And, moreover, only when MathML is being generated.  It causes havoc in
_groff_ output.


$ cat EXPERIMENTS/eqn-use-big.roff
.EQ
big sin x
.EN
.EQ
size big sin x
.EN
$ eqn -TMathML EXPERIMENTS/eqn-use-big.roff 
.if !dEQ .ds EQ
.if !dEN .ds EN
.EQ
<math><mrow><mi>b</mi><mi>i</mi><mi>g</mi><mstyle
mathvariant='normal'><mtext>sin</mtext></mstyle><mi>x</mi></mrow></math>
.EN
.EQ
<math><mrow><mstyle mathsize='big'><mstyle
mathvariant='normal'><mtext>sin</mtext></mstyle></mstyle><mi>x</mi></mrow></math>
.EN
$ eqn -Tascii EXPERIMENTS/eqn-use-big.roff |nroff -Tascii | cat -s
troff: EXPERIMENTS/eqn-use-big.roff:14: warning: numeric expression expected
(got 'b')
bigsinx sinx
$ eqn -Tascii EXPERIMENTS/eqn-use-big.roff 
.if !dEQ .ds EQ
.if !dEN .ds EN
[...]
.nr 0w2 +\w\(EQ\,b\&i\&g\/\,x\/\(EQ
[...]
.as1 10
\&\E*[0sfont]\f[I]\s'\En[0ssize]u'\,b\&i\&g\/\h'17M'\f[R]sin\f[\n[0f5]]\h'17M'\,x\/\E*[0rfont]
[...]
.ps big \" GBR: !!!!
[...]


(You might notice that the line number in the diagnostic is off.  This is due
to _eqn_ itself producing invalid _groff_ input, for which line numbers are
generally not reliable because `lf` requests must be used to align those
numbers with user expectations.)







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