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Date:      Mon, 20 Jun 2011 12:28:09 -0700
From:      Chuck Swiger <cswiger@mac.com>
To:        Stephen Montgomery-Smith <stephen@missouri.edu>
Cc:        Niclas Zeising <niclas.zeising@gmail.com>, Roman Divacky <rdivacky@freebsd.org>, "freebsd-ports@freebsd.org" <freebsd-ports@freebsd.org>
Subject:   Re: [ANNOUNCE]: clang compiling ports
Message-ID:  <B94EED31-5992-44E6-B72C-C37D4D7FEF0F@mac.com>
In-Reply-To: <4DFF9AE3.10609@missouri.edu>
References:  <20110620153753.GA41541@freebsd.org> <4DFF73E3.5010405@gmail.com> <4DFF76C7.5070001@missouri.edu> <432743E3-272A-40F5-AF31-6C1805F620F3@mac.com> <4DFF9AE3.10609@missouri.edu>

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On Jun 20, 2011, at 12:09 PM, Stephen Montgomery-Smith wrote:
>> top_button_cross() probably should be declared as returning void.  What's presumably happening is that it gets a default return type of int since it doesn't otherwise specify a return type, and then fails to have an explicit return, which is an error.
> 
> Is a return with no value, from a function of type int, meant to be an error in K&R code?

I don't believe so, but pure K&R didn't require compilers to perform any sanity checking of function return types.  This led to all sorts of bugs, which is why lint was invented and why ANSI-C compilers do expect function prototypes and perform function return-type checking.

> If so, I will change the code so that "return" becomes "return 0".
> 
> Otherwise, I think the clang compiler should be changed so that this is a warning, not an error.  Or at least an error that can be switched off with -Wno-return-type.
> 
> I will say that I have no desire to put ansii patches into working K&R code.

It sounds like you want Clang to support -traditional.
It explicitly does not do so, although there is a bug filed as:

  http://llvm.org/bugs/show_bug.cgi?id=4557

The best course is to convert K&R C code to C89/ANSI; failing that, perhaps use gcc for things which require -traditional instead of Clang (although GCC seems to be depreciating -traditional also).

Regards,
-- 
-Chuck




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