Fwd: make-system and gensyms

[Eric Swenson]

make-system make generate a dummy system, with a GENSYM’ed name, if there are 
macros that need compiling and loading prior to the other non-macro modules in 
a system.  It then invokes make-system (recursively) on this dummy system, and 
after this returns, it performs the functionality of the original system 
specified as the parameter.  The GENSYM’ed name of the dummy system appears 
fixed as “g0052”, which is returned by a call to (GENSYM) in 
PASS-TRANSFORMATION in maksys.lisp.181.  Now, standalone, GENSYM, invoked 
multiple times, returns different symbols in the keyword package — as it 
should.  But for some reason, if you invoke make-system multiple times, the 
dummy system will always be named “g0052”.  This is manifested when make-system 
writes the message:

Writing compiler warnings data base to file CHAOS3: /g0052-cwarns.lisp.  

to the console.  You will see this message prior to the make-system on the mail 
system, which will look like this:

Writing compiler warnings data base to file CHAOS3: /math-cwarns.lisp.

when compiling the main system (in this example, MATH).  

The code in question appears to be this:

(DEFUN MAYBE-RELOAD-FILE (FILE KEYWORDS &AUX SYSTEM)
 (OR (SETQ SYSTEM (SEND FILE :GET 'MAYBE-RELOAD-SYSTEM))
     (LET* ((LISP (SEND FILE :SOURCE-PATHNAME))
        (QFASL (SEND FILE :NEW-PATHNAME :TYPE :QFASL :VERSION :NEWEST))
        ;; Compiled if qfasl ever loaded, else interpreted if lisp ever loaded,
        ;; else check file computer and default to interpreted.
   ;** this doesnt really win with new GENERIC-PATHNAME scheme.
       ; should be fixed by adding mode of loading to :FILE-ID-PACKAGE-ALIST 
element,
   ; I guess.  Seems pretty random anyway.
        (COMPILED (COND ((SEND QFASL :GET :FILE-ID-PACKAGE-ALIST) T)
                ((SEND LISP :GET :FILE-ID-PACKAGE-ALIST) NIL)
                ((PROBEF QFASL) T)
                (T NIL))))
   (SETQ SYSTEM (GENSYM))
   (DEFSYSTEM-1 SYSTEM `((,(IF COMPILED :COMPILE-LOAD :READFILE)
                  (,(STRING FILE))))
            T NIL)
   (SEND FILE :PUTPROP SYSTEM 'MAYBE-RELOAD-SYSTEM)))
 (APPLY 'MAKE-SYSTEM SYSTEM
    (NCONC (LOOP FOR KEY IN KEYWORDS
             WHEN (EQ KEY :BATCH) COLLECT :NOWARN
             ELSE UNLESS (MEMQ KEY '(:NOLOAD :RELOAD :RECOMPILE :PRINT-ONLY))
             COLLECT KEY)
       '(:COMPILE :NO-RELOAD-SYSTEM-DECLARATION))))

Note that the dummy system is created with the name (GENSYM), and this is 
“made” in the APPLY above.

I thought, perhaps that some macro expansion was being cached and reused, but I 
don’t see any such macro expansions above.

Why is the system name not unique here, each time a new system is made (that 
requires a dummy macro system).  

— Eric