From:	Erik Max Francis <max AT alcyone DOT com>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: strange warning
Date:	Sat, 14 Dec 1996 19:49:18 -0800
Organization:	Alcyone Systems
Lines:	25
Message-ID:	<32B3753E.26758647@alcyone.com>
References:	<58vhpj$ors AT nntp DOT novia DOT net>
NNTP-Posting-Host:	newton.alcyone.com
Mime-Version:	1.0
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

Alaric Dailey wrote:

> I am trying to create a make file for a package of source code written in
> ansi-C everything seems to compile ok except for one code fragment.  see
> below. this  code always produces  this warning
> 
> context.c: In function `go_deep':
> context.c:34 warning: function returns  address of local variable

This is inherently a bad thing.  Perhaps the authors are trying to do
something tricky based on the knowledge that in the limited circumstances
this is to be used everything will be okay, but that seems unlikely in a
preemptive multitasking system.

Basically, the problem is that an automatic variable is destroyed once the
block it is declared in is left.  Returning the address of an automatic
variable is a Bad Thing To Do -- it means that you're pointing to an area of
the stack which may be reclaimed at any time.

-- 
                             Erik Max Francis | max AT alcyone DOT com
                              Alcyone Systems | http://www.alcyone.com/max/
                         San Jose, California | 37 20 07 N 121 53 38 W
                                 &tSftDotIotE | R^4: the 4th R is respect
     "You must surely know if man made heaven | Then man made hell"

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