Mailinglist Archive: opensuse-packaging (266 mails)

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Re: [opensuse-packaging] How to disable no-return-in-nonvoid-function?
  • From: Guido Berhoerster <gber@xxxxxxxxxxxx>
  • Date: Mon, 26 Nov 2012 13:58:14 +0100
  • Message-id: <20121126125813.GA4247@hal.local.invalid>
* Ruediger Meier <sweet_f_a@xxxxxx> [2012-11-26 13:42]:
On Monday 26 November 2012, Dominique Leuenberger a.k.a DimStar wrote:
A warning by the compiler does not mean you don't have to care for
it.. It means the programmer is responsible to know what is happening
in this code and there is NO guarantee between gcc versions that this
is not 'just changing'.

The only valid solution is to fix the code.

See for example this code piece (C++)

###
#include <iostream>

int foo() {
int a = 5;
int b = a + 1;
}

int main() { std::cout << foo() << std::endl; }
###

What is the recommended output of this? this example is somewhat
simple enough to understand what is going on... BUT the bad thing is,
if you ever extend the function foo() with anything AFTER, you migh
get a new return value, which is not what you wanted... hence the
warning.

Best regards,
Dominique (who wishes upstreams would learn about -Werror -Wall)


The example below also gives you "control reaches end of non-void
function" and obviously the compiler (gcc 4.5.1) is wrong. A valid
solution here is to ignore the warning or to fix gcc.

int main()
{
int i = 1;
if (i == 1) {
return 1;
}
}

(This is a stupid trivial example. You can imagine that there are also
real world examples where the programmer knows for sure that the
warning is invalid.)


Best regards,
Dominique (who wishes upstreams would learn about -Werror -Wall)

Yes, if you want to break your build on any compiler update.

FYI
https://lkml.org/lkml/2011/4/21/325

I find it generally useful to rebuild packages with clang or even
scan-build when investigating compiler warnings. While it isn't
completely without false positives, it is vastly better than gcc
and its warnings are actually readable and give you some context
often allowing you to issues or non-issues without even digging
into the source files.
--
Guido Berhoerster
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