proposal: add -Werror-implicit-function-declaration to the default optflags

[Hans de Goede]

Lubomir Kundrak wrote:
> On Mon, 2008-03-24 at 22:03 +0100, Hans de Goede wrote:
>> Hi all,
>>
>> This is a new thread spawning from the "3.6% of heads up: Please correct your 
>> #includes or optflags use" thread.
>>
>> I would like to propose to add "-Werror-implicit-function-declaration" to the 
>> default optflags. Why? Because missing prototypes can cause all sorts of problems:
> 
> You're not the first one with this idea. It's inevitable that this will
> happen at some time. But, as was expressed in some other place of this
> thread this needs some effort before it's done. It's going to break a
> big part of distribution (far more than 3.6%) if it's done now, and
> would need serious effort to be done.
> 

I disagree, yes it will probably break a large part of the distribution, but 
fixing it does not have to be a huge effort. My plan is:
%define optflags "current_optflags -Werror-implicit-function-declaration"
%define lame_optflags "current_optflags"

And the if it turns out an application / lib is rather broken with regards to 
this and fixing it is non trivial, one can simply do:
export CFLAGS="%lame_optflags"
export CXXFLAGS="%lame_optflags"

Before %configure, and if one is using optflags manually in an other way, 
simply replace the use of %optflags there with %lame_optflags.

This way:
1) working around the breakage for not trivial to fix packages is easy
2) We can have a script which greps CVS for lame_optflags and reports packages
    which still need proper fixing.

So the effort for doing this does not need to be that big, as long as Matt does 
some mass rebuilds with the new flags in place to give people early warning of 
breakage before a mass rebuild during the F-10 cycle, if the F-10 cycle will 
have a mass rebuild that is.

> So, why not create a wiki page, plan how to make this harm the least it
> can (limit the number of packages affected by calling for changes before
> the rule is enforced), and get it through packaging commitee (or
> fesco?).

I could do that, but currently there has been only a little feedback in this 
thread, so lets discuss this some more first.

Regards,

Hans