Compiler problem

[LPD at MIT-AI (L. Peter Deutsch)]

I had a mysterious problem in which a string constant computed by
string-append during macro expansion was getting smashed in the
eventual compiled code.  I believe the cause is that the compiler
rebinds the default working area, and the string is getting put
there and not copied.  This loses because the compiler's working
area gets zapped at every compilation.  The problem probably doesn't
show up when compiling to a QFASL file, since the string gets
written out before it gets smashed, but in my situation I was using
control-top-C to compile into memory.

I can fix this with a relatively minor change in my code, in this
particular case, but if this is really the cause of the problem,
it obviously has the potential for causing many subtle difficulties
in the future.