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From: trt@rti.rti.org (Thomas Truscott)
Newsgroups: comp.compilers
Subject: Re: Semicolons (Re: Low-Rent Syntax)
Summary: The real problem is the compiler, not the language
Keywords: C, design, debug
Message-ID: <4032@rtifs1.UUCP>
Date: 24 Aug 90 01:40:41 GMT
References: <9008202341.AA06543@llama.ingres.com>
Sender: compilers-sender@esegue.segue.boston.ma.us
Reply-To: trt@rti.rti.org (Thomas Truscott)
Organization: Research Triangle Institute, RTP, NC
Lines: 41
Approved: compilers@esegue.segue.boston.ma.us

> >	while( x );/* a nasty case */
> >		x--;
> 
> The real problem here is not with the semicolon, it is with the grammar 
> production that dominates C and Pascal:

The problem is with the compiler that fails to issue warnings about the
obvious problems with the above code:

prog.c: line 12: degenerate "while" loop
prog.c: line 13: dubious indentation level.


Tinkering with language syntax can go only a short distance towards
stamping out the bugs that typical code contains.  Syntax restrictions
would be hard put to catch bugs such as:

prog.c: line 20: variable "i" may be used before set

	p = malloc(strlen(s));
			    ^
prog.c: line 32: was "strlen(s) + 1" intended?

I believe this type of diagnostic assistance, fueled by examples of
typical errors, is far more effective than adding syntactic handcuffs.  I
was quite surprised to learn, this evening, of a C compiler that actually
does this level of diagnostic analysis.  (Along with convenient options to
control the degree of nit-picking).  Perhaps if it becomes widely
available (and demanded), compilers for other languages will do it too, to
catch errors such as:

	while ( x )
		y--;
	endwhile;

Tom Truscott
[Which compiler is it?  And when I really do want to write a degenerate
while loop, how do I tell it not to complain? -John]
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