[metapost] Bug?

[Pétiard François]

Hello

My config: windows10 pro, MiKTeX 2.9 updated

The file:

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

vardef TEX primary s =
write "verbatimtex"                             to "mptextmp.mp";
write "%&latex"                              to "mptextmp.mp";
write "\documentclass[12pt,french]{article}"    to "mptextmp.mp";
write "\usepackage[T1]{fontenc}"                to "mptextmp.mp";
write "\usepackage{babel}"                      to "mptextmp.mp";
write "\pagestyle{empty}"                       to "mptextmp.mp";
write "\begin{document}"                        to "mptextmp.mp";
write "\sffamily\Huge\bfseries"                 to "mptextmp.mp";
write "etex;"                                   to "mptextmp.mp";
write "btex "&s&" etex"                         to "mptextmp.mp";
write EOF                                       to "mptextmp.mp";
scantokens "input mptextmp"
enddef;
prologues:=3;
outputformat:="eps";
outputtemplate:="%j_%3c.mps";
for i=1 upto 502:
   beginfig(i);
     label(TEX("i: $"&decimal(i)&"$"),(0,0));
   endfig;
endfor;
end;

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

compiles without problem (mpost -tex=latex) and I obtain 502 pictures 
but the file (note \usepackage{kpfonts}):

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

vardef TEX primary s =
write "verbatimtex"                             to "mptextmp.mp";
write "%&latex"                              to "mptextmp.mp";
write "\documentclass[12pt,french]{article}"    to "mptextmp.mp";
write "\usepackage[T1]{fontenc}"                to "mptextmp.mp";
write "\usepackage{kpfonts}"                    to "mptextmp.mp";
write "\usepackage{babel}"                      to "mptextmp.mp";
write "\pagestyle{empty}"                       to "mptextmp.mp";
write "\begin{document}"                        to "mptextmp.mp";
write "\sffamily\Huge\bfseries"                 to "mptextmp.mp";
write "etex;"                                   to "mptextmp.mp";
write "btex "&s&" etex"                         to "mptextmp.mp";
write EOF                                       to "mptextmp.mp";
scantokens "input mptextmp"
enddef;
prologues:=3;
outputformat:="eps";
outputtemplate:="%j_%3c.mps";
for i=1 upto 502:
   beginfig(i);
     label(TEX("i: $"&decimal(i)&"$"),(0,0));
   endfig;
endfor;
end;

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

makes an error after 250 pictures and the log is:

This is MetaPost, version 2.01 (MiKTeX 21.12.10)  22 DEC 2021 18:24
**test.mp
(C:/Program Files/MiKTeX/metapost/base/mpost.mp (C:/Program 
Files/MiKTeX/metapost/base/plain.mp
Preloading the plain mem file, version 1.005) ) (./test.mp 
(./mptextmp.mp) [1{psfonts.map}{8r.enc}<j
kpssbn8a.pfb><jkpmn8a.pfb>] (./mptextmp.mp) 
[2<jkpssbn8a.pfb><jkpmn8a.pfb>] (./mptextmp.mp) [3<jkpss
bn8a.pfb><jkpmn8a.pfb>] (./mptextmp.mp) [4<jkpssbn8a.pfb><jkpmn8a.pfb>] 
(./mptextmp.mp) [5<jkpssbn8a
.pfb><jkpmn8a.pfb>] (./mptextmp.mp) [6<jkpssbn8a.pfb><jkpmn8a.pfb>] 
(./mptextmp.mp) [7<jkpssbn8a.pfb
 ><jkpmn8a.pfb>] (./mptextmp.mp) [8<jkpssbn8a.pfb><jkpmn8a.pfb>] 
(./mptextmp.mp) [9<jkpssbn8a.pfb><jk
pmn8a.pfb>] (./mptextmp.mp) [10<jkpssbn8a.pfb><jkpmn8a.pfb>] 
(./mptextmp.mp) [11<jkpssbn8a.pfb><jkpm
n8a.pfb>] (./mptextmp.mp) [12<jkpssbn8a.pfb><jkpmn8a.pfb>] 
(./mptextmp.mp) [13<jkpssbn8a.pfb><jkpmn8
a.pfb>] (./mptextmp.mp) [14<jkpssbn8a.pfb><jkpmn8a.pfb>] (./mptextmp.mp) 
[15<jkpssbn8a.pfb><jkpmn8a.
pfb>] (./mptextmp.mp) [16<jkpssbn8a.pfb><jkpmn8a.pfb>] (./mptextmp.mp) 
[17<jkpssbn8a.pfb><jkpmn8a.pf
b>] (./mptextmp.mp) [18<jkpssbn8a.pfb><jkpmn8a.pfb>] (./mptextmp.mp) 
[19<jkpssbn8a.pfb><jkpmn8a.pfb>
] (./mptextmp.mp) [20<jkpssbn8a.pfb><jkpmn8a.pfb>] (./mptextmp.mp) 
[21<jkpssbn8a.pfb><jkpmn8a.pfb>]

[...]
(./mptextmp.mp) [250<jkpssbn8a.pfb><jkpmn8a.pfb>] (./mptextmp.mp
 >> mptextmp.mp
 >> mptextmp.mpx
! ! Unable to read mpx file.
l.11 btex
           i: $251$ etex
The two files given above are one of your source files
and an auxiliary file I need to read to find out what your
btex..etex blocks mean. If you don't know why I had trouble,
try running it manually through MPtoTeX, TeX, and DVItoMP

250 output files written: test_001.mps .. test_250.mps

I don't understand:

* why it's OK with cm fonts and not with kpfonts

* why it's OK for 250 pictures and not after...

???

Best regards

François Pétiard