GNU bug report logs - #23640
25.1.50; Getting rid of compiler warnings

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From: Andy Moreton <andrewjmoreton <at> gmail.com>
To: 23640 <at> debbugs.gnu.org
Subject: bug#23640: 25.1.50; Getting rid of compiler warnings
Date: Tue, 31 May 2016 09:03:00 +0100

On Mon 30 May 2016, Paul Eggert wrote:

> Ken Brown wrote:
>> Why not just unconditionally initialize the variables that gcc complains about?
>
> That could make the code harder to understand. Someone who sees "int i = 0;"
> can reasonably infer that the 0 is needed, i.e., that a later part of the code
> needs the 0. Someone who sees "int i IF_LINT (= 0);" should be under no such
> illusion.

Surely this makes the code easier to understand, since "int i = 0;"
immediately shows that the variable is always initialised, so there is
no need to check that it is initialised before use on all code paths
(and recheck after making any chages during maintenance).

Given that the performance cost of this is likely to be unmeasurably
small, the IF_LINT stuff is either unneccessary clutter, or hiding a
latent bug.

> The FreeBSD and Cygwin uses of 'lint' violate the C Standard. For example:
>
> #define lint 1
> #include <stdio.h>
> _Noreturn int x;
>
> This program violates a constraint so the C Standard requires a compile-time
> diagnostic, but from what you say on FreeBSD and Cygwin the compiler
> misbehaves and silently ignores the _Noreturn. I see that HBBroeker is
> independently making a similar point on the Cygwin mailing list
> <https://www.cygwin.com/ml/cygwin/2016-05/msg00405.html>.

That may be so, but any codebase has to deal with the world as it is,
not the ideal in one of the applicable standards.

    AndyM

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