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From: dinapoli@rodan.acs.syr.edu (Ron DiNapoli)
Newsgroups: comp.sys.mac.programmer
Subject: MPW 2.0 and 3.0/3.1
Message-ID: <3238@rodan.acs.syr.edu>
Date: 9 May 90 15:16:32 GMT
Sender: dinapoli@rodan.acs.syr.edu
Reply-To: dinapoli@rodan.acs.syr.edu (Ron DiNapoli)
Distribution: usa
Organization: Syracuse University, Syracuse, NY
Lines: 57


A few weeks back I posted a message regarding a problem I was having with
the MPW 3.0 C pre-processor.  This problem reared its ugly head when I at-
tempted to port my MPW 2.0 C code to 3.0.  The majority of responses I re-
ceived advised me to upgrade to MPW C 3.1.  I did this, but the problem 
did not go away.  Well I finally discovered what was going wrong... I had the
following macro defined:

	#define OP(tkdef,tkname,d1,d2) {#tkdef,tkname,d1,d2}

and I wanted to expand the following:

	OP(TK_SSLASH,"//",ASSC_YFX,400)

Anybody see the problem?  In MPW C 3.0 and later, the '//' symbol stands
for a comment.  It also seems that the preprocessor is unable to detect
that this particular comment character is occurring within a string.  
Since it doesn't, the preprocessor sees the open end of a string, and never
finds the closing " (because the real one was 'commented' out) before its
internal buffer overflows.  Once discovered, the fix was easy.  I just 
changed this particular occurrance of OP to:

	OP(TK_SSLASH,"/\/",ASSC_YFX,400)


So, it this a bug?  In my opinion it isn't.  Take for example the following 
macro definition:

#define PRINTIT(prstr) printf("PRINTIT has been called with: %s\n",prstr);

and the following program:

main()
{
	PRINTIT("/* This is a comment */")
	PRINTIT(" This is normal text ")
	PRINTIT(" // Another type of comment")
}

The preprocessor (3.1 C) will output the following:

main()
{
	printf("PRINTIT has been called with: %s\n","");
	printf("PRINTIT has been called with: %s\n"," This is normal text ");

Obviously, it was unable to finish expanding the last macro because of the 
// comment character.  Attempting to further compile this example will 
NOT work!

Note how in the first occurrance of the PRINTIT macro, the text between the
/* */ comment characters does not appear.  This tells me that in the 3.0/3.1
C preprocessor, comments are "taken out" regardless of where they appear.
Thus my problems with the '//' in my string seems consistent with this
philosophy.  For this reason, I would say it is not a bug at all!

Ron D.