Compiling my simpler version of Peter's program with 'm2c C all' exposes C double assigning variables, thus losing parameter values when nested:
(par_WriteCard_InOut._x=((par_add_Bug._i=(11),par_add_Bug._j=((par_add_Bug._i=(100),par_add_Bug._j=(1000),_add_Bug(&par_add_Bug))),_add_Bug(&par_add_Bug))),par_WriteCard_InOut._n=(0),_WriteCard_InOut(&par_WriteCard_InOut));

This returns 1200:
InOut.WriteInt(add(11, add(100, 1000)), 0);
This returns 1111:
InOut.WriteInt(add(add(1, 10), 1100), 0);

Thanks and sorry. My mistake.
I used the search box to the left of the screen and it had/has an option "bugs", which, as it turns out, is global, not project specific.
The Free Software Foundation seems to do a very remarkable and important job, but I think that sometimes they should pay more attention to the quality of their products. May be the approach "less, but better" might help them.
I'll try to resubmit the flaw report to the Octave flawtrack.
Thanks again for Your helpful comment. :)

Martin, you seem to be talking about a problem with Octave. You're reporting it in the wrong place, this project is about m2c, a Modula2 compiler. For instructions on reporting on Octave, see https://www.gnu.org/software/octave/bugs.html .

Sorry, the markup collided with the code in my previous comment. Hopefully this is a bit better:
restatementstart
May be it's a different flaw, but the plotting of
y=sin(x)+sin(x+4 * sin(x))
works and the plotting of
y=sin(x)+sin(x Y 4 * sin(x))
where the Y is a star, id est multiplication,
did not work.
restatementend

May be it's a different flaw, but the plotting of
y=sin(x)+sin(x+4*sin(x))
works and the plotting of
y=sin(x)+sin(x*4*sin(x))
does not work.
verbatimstart
octave:7> x=10:0.1:10;
octave:8> plot(x,sin(x)+sin(x+4*sin(x)));
octave:9> plot(x,sin(x)+sin(x*4*sin(x)));
error: operator *: nonconformant arguments (op1 is 1x201, op2 is 1x201)
error: evaluating argument list element number 1
error: evaluating argument list element number 2
octave:9>
verbatimend

Consider the program below. It should output "1111", but the actual output is "1200". This is related to, but not the same as, Debian bug #168588.
MODULE Bug;
IMPORT InOut;
PROCEDURE add(i, j: INTEGER): INTEGER;
BEGIN RETURN i + j
END add;
BEGIN
InOut.WriteInt(add(add(1, 10), add(100, 1000)), 0);
InOut.WriteLn;
END Bug.
