Path: utzoo!utgpu!water!watmath!clyde!rutgers!sri-spam!sri-unix!quintus!sun!pitstop!sundc!seismo!uunet!sdrc!scjones
From: scjones@sdrc.UUCP (Larry Jones)
Newsgroups: comp.lang.c
Subject: Re: "Noalias" warning and questions
Summary: No problems here ...
Message-ID: <213@sdrc.UUCP>
Date: 12 Feb 88 23:06:34 GMT
References: <8012@elsie.UUCP>
Organization: Structural Dynamics Research Corp., Cincinnati
Lines: 36

In article <8012@elsie.UUCP>, ado@elsie.UUCP (Arthur David Olson) writes:
< [stuff about noalias]
< 
< Now a bit of background for a few questions.  Here are two function prototypes
< from the proposed Standard:
< 	int strcmp(const noalias char *s1, const noalias char *s2);
< 	void perror(const noalias char *s);
< 
< 1.  Does the program
< 	#include "stdlib.h"
< 	main() {
< 		char	array[3];
< 		array[0] = '\0';
< 		return strcmp(array, array);
< 	}
<     violate any constraints?  If so, must the compiler detect the violation?
< 
< [other similar examples]

Nope, no problems here.  The definition of noalias doesn't forbid aliases, it
just says that if you do have aliases and >modify< one of them, all bets are
off.  Since strcmp() doesn't modify any of its arguments (as evidenced by the
"const"), your examples are all fine and dandy.

< 4.  What is the "noalias" in the "perror" declaration designed to do?

The same thing as it does in the "strcmp" declaration - basically nothing.
It's really only applicable to output arguments but we decided to put it
on all the library pointers for consistency's sake.
-- 

----
Larry Jones                         UUCP: uunet!sdrc!scjones
SDRC                                MAIL: 2000 Eastman Dr., Milford, OH  45150
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