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Re: prepare to fix build failures with new GCC versions



On 28.02.2011 08:02, Raphael Hertzog wrote:
> On Sun, 27 Feb 2011, Matthias Klose wrote:
>> Unreflected usage of symbols files for C++ libraries
>> - ----------------------------------------------------
>>
>> These seem to be limited to Qt and KDE related libraries.
>>
>> Apparently g++-4.4 did emit references to symbols defined in header files of
>> depending libraries.  At least some of these are not emitted anymore with 4.5
>> and 4.6.  Packages calling dpkg-gensymbols with -c2 or higher, fail to build.
>>
>> The mangling for virtual thunks did change, and generates different symbols on
>> some architectures.  The issues can be avoided by using the unmangled names.
> 
> Well, if the mangling changed it means binaries linked against old
> libraries will no longer work so it's rather good that the symbols files
> doesn't match any more because you have to bump the mimimum version number
> for that symbol.

can you show that these symbols are actually referenced?

> So "avoiding" the problem is not really a goal in this case... a symbols
> files which does match based on the unmangled name would have let this
> mistake slip through. :-|

no, if there are no references to these symbols, then adding these symbols is
just an annoyance.

  Matthias


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