Re: NDEBUG when building packages?

[Mathieu Malaterre <malat@debian.org>]

On Sat, Feb 23, 2013 at 11:09 AM, Vincent Cheng <vincentc1208@gmail.com> wrote:
> On Sat, Feb 23, 2013 at 1:39 AM, Mathieu Malaterre <malat@debian.org> wrote:
>> On Fri, Feb 22, 2013 at 9:52 PM, Russ Allbery <rra@debian.org> wrote:
>>> Ian Jackson <ijackson@chiark.greenend.org.uk> writes:
>>>> Mathieu Malaterre writes ("Re: NDEBUG when building packages?"):
>>>
>>>>> In that case, this should really be clarified. A lot of debian/cmake
>>>>> packages are actually doing:
>>>
>>>>> -DCMAKE_BUILD_TYPE:STRING=Release
>>>
>>>>> within there debian/rules files. This settings by default compiles
>>>>> with: `-O3 -DNDEBUG`
>>>
>>>> OMG WTF BBQ
>>>
>>>> Certainly -DNDEBUG should never be used unless upstream explicitly say
>>>> that it's intended to be supported, and usually not even then.
>>>
>>> Also, -O3 is generally considered rather iffy.  It's not very well-tested
>>> and in various versions of GCC it tended to make the code slower, not
>>> faster (usually because it unrolled loops too far and blew the CPU cache).
>>> It's also had various code generation bugs from time to time.
>>>
>>> I wouldn't use -O3 without benchmarking of that specific code to confirm
>>> that it really improves matters.
>>
>> Seems like everyone agreed. I'll report a bug to lintian package to
>> have it check for this string in d/rules:
>>
>> http://codesearch.debian.net/search?q=DCMAKE_BUILD_TYPE:STRING%3DRelease
>
> We should also suggest that packages use
> -DCMAKE_BUILD_TYPE=RelWithDebInfo instead (-g -O2). In fact, I think
> that this would be a sensible default for packages using debhelper's
> cmake integration. Sounds like another wishlist bug for debhelper...

cmake from sid makes it even harder. RelWithDebInfo now contains
-DNDEBUG ... I have to source-upload all my packages :(

$ grep NDEBUG ChangeLog.manual
      Add -DNDEBUG to RelWithDebInfo flags where where Release flags had it.


The solution (backward compat) is now:

Either do *not* define CMAKE_BUILD_TYPE, or define CMAKE_BUILD_TYPE to
Debug (and hope -DNDEBUG does not creep in ever)

2cts