From:	"John M. Aldrich" <fighteer AT cs DOT com>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: v2 unwanted warnings
Date:	Thu, 21 Nov 1996 20:31:06 -0800
Organization:	Three pounds of chaos and a pinch of salt
Lines:	50
Message-ID:	<32952C8A.3728@cs.com>
References:	<EF21E372FE AT fs2 DOT mt DOT umist DOT ac DOT uk>
Reply-To:	fighteer AT cs DOT com
NNTP-Posting-Host:	ppp211.cs.com
Mime-Version:	1.0
To:	"A.Appleyard" <A DOT APPLEYARD AT fs2 DOT mt DOT umist DOT ac DOT uk>
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

A.Appleyard wrote:
> 
>   Please reply to me also in person, as I had to unsubscribe from djgpp email
> group due to email intray overload. I am sorry to keep troubling you.
> 
>   (0) About how many messages are there per day now on djgpp email group?

It's around 40-50 nowadays, but as Eli suggested you can simply read the
newsgroup.  ;)

>   I have just had my first go with v2, which I downloaded from Hensa at
> Lancaster (England) today. I have a big program (a text editor), which v1 has
> compiled many times under -Wall without complaint, but under v2 with -Wall:-

v1 and v2 are substantially different compilers.  I suggest seriously
that you read the v2 FAQ (v2/faq202b.zip) for information on all the
changes.

>   (2) Can this warning be suppressed specifically, similarly?:-
>     `warning: suggest parentheses around assignment used as truth value'

No!  It is a very bad idea to suppress this sort of warning.  The
precedence of the '=' and '==' operators can be very confusing, and if
you do it wrong you'll get undesired results.  For example:

  if ( x = y == z )
     ...

In this expression, (y == z) is evaluated first, and the value of that
expression is assigned to x.  If this is truly what you intended, then
you should explicitly put parentheses around the (y == z).  If not, then
this is a serious bug in your program, and should be replaced by:

  if ( ( x = y ) == z )
     ...

That warning is there because the compiler is unable to distinguish
between correct and incorrect applications of these operators.  Eli
suggested a method to use, but you should only use it if you KNOW that
all your truth expressions are correct!

-- 
John M. Aldrich, aka Fighteer I <fighteer AT cs DOT com>

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