[Graph] redefinition of hash<void*> clashes with boost/functional/hash.hpp
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. Thanks
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
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
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Ioannis Papadopoulos -
Jeremiah Willcock