Re: [Boost-users] [Graph] redefinition of hash<void*> clashes with boost/functional/hash.hpp

Subject: Re: [Boost-users] [Graph] redefinition of hash<void*> clashes with boost/functional/hash.hpp
From: Ioannis Papadopoulos (ipapadop_at_[hidden])
Date: 2011-10-26 22:34:03

On 10/26/2011 8:18 PM, Jeremiah Willcock wrote:
> On Wed, 26 Oct 2011, Ioannis Papadopoulos wrote:
>
>> Hi,
>>
>> In graph/detail/adjacency_list.hpp:2766 there is a specialization of
>> struct hash for void*. Isn't the generic pointer specialization in
>> functional/hash/extensions.hpp:172 enough?
>>
>> The problem I am facing is the following (which I couldn't reproduce
>> in a trivial example):
>>
>> 1. I include <boost/functional/hash.hpp> and
>> <boost/tr1/unordered_map.hpp>
>> 2. I create an std::tr1::unordered_map<void*, int> and typedef
>> std::tr1::unordered_map<void*, int>::iterator iterator_type;
>> 3. In some test file that includes <boost/graph/adjacency_list.hpp>
>> and uses it, I get the following error (gcc 4.4.5/4.6.1):
>> /usr/local/include/boost/graph/detail/adjacency_list.hpp:2766: error:
>> specialization of ‘boost::hash<void*>’ after instantiation
>> /usr/local/include/boost/graph/detail/adjacency_list.hpp:2766: error:
>> redefinition of ‘struct boost::hash<void*>’
>> /usr/local/usr/include/boost/functional/hash/extensions.hpp:172:
>> error: previous definition of ‘struct boost::hash<void*>’
>>
>> I can resolve it by providing my own hash functor to the unordered_map
>> (which causes hash<void*> not to be instantiated). I will keep trying
>> to provide a trivial example.
>
> I have removed that from the trunk (boost::hash always provides that
> specialization now). See if that helps (if you don't want to get the
> trunk version, the only change is removing the hash<void*> part of
> boost/graph/detail/adjacency_list.hpp).
>
> -- Jeremiah Willcock

Yes, that does the trick. Thanks