Reference to stack memory associated with local variable 'x' returned

[brian.doig@…]

It looks like x is not being passed in by reference. Because of this a copy is made on the stack. The operator returns x.value as a reference which is dangerous since x will go out of scope.

This bug occurred with Xcode 4 beta 2, and with the latest version of clang/llvm from the open source project.

CompileC /Users/bdoig/Library/Developer/Xcode/DerivedData/WDStoreTest-dbsxxdunpvzihagbzjvgylinzzaf/Build/Intermediates/WDStoreTest.build/Debug-iphonesimulator/WDStoreTest.build/Objects-normal/i386/TopoSort.o /Users/bdoig/Dropbox/WData/TopoSort.mm normal i386 objective-c++ com.apple.compilers.llvm.clang.1_0.compiler

cd /Users/bdoig/Dropbox/WDStoreTest setenv LANG en_US.US-ASCII setenv PATH "/Xcode4/Platforms/iPhoneSimulator.platform/Developer/usr/bin:/Xcode4/usr/bin:/usr/bin:/bin:/usr/sbin:/sbin" /Xcode4/Platforms/iPhoneSimulator.platform/Developer/usr/bin/clang -x objective-c++ -arch i386 -fmessage-length=0 -pipe -fdiagnostics-print-source-range-info -fdiagnostics-show-category=id -Wno-trigraphs -fpascal-strings -O0 -Wreturn-type -Wunused-variable -DIPHONE_OS_VERSION_MIN_REQUIRED=30200 -isysroot /Xcode4/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator4.0.sdk -fasm-blocks -mmacosx-version-min=10.6 -gdwarf-2 -fvisibility=hidden -fobjc-abi-version=2 -fobjc-legacy-dispatch -iquote /Users/bdoig/Library/Developer/Xcode/DerivedData/WDStoreTest-dbsxxdunpvzihagbzjvgylinzzaf/Build/Intermediates/WDStoreTest.build/Debug-iphonesimulator/WDStoreTest.build/WDStoreTest-generated-files.hmap -I/Users/bdoig/Library/Developer/Xcode/DerivedData/WDStoreTest-dbsxxdunpvzihagbzjvgylinzzaf/Build/Intermediates/WDStoreTest.build/Debug-iphonesimulator/WDStoreTest.build/WDStoreTest-own-target-headers.hmap -I/Users/bdoig/Library/Developer/Xcode/DerivedData/WDStoreTest-dbsxxdunpvzihagbzjvgylinzzaf/Build/Intermediates/WDStoreTest.build/Debug-iphonesimulator/WDStoreTest.build/WDStoreTest-all-target-headers.hmap -iquote /Users/bdoig/Library/Developer/Xcode/DerivedData/WDStoreTest-dbsxxdunpvzihagbzjvgylinzzaf/Build/Intermediates/WDStoreTest.build/Debug-iphonesimulator/WDStoreTest.build/WDStoreTest-project-headers.hmap -F/Users/bdoig/Library/Developer/Xcode/DerivedData/WDStoreTest-dbsxxdunpvzihagbzjvgylinzzaf/Build/Products/Debug-iphonesimulator -I/Users/bdoig/Library/Developer/Xcode/DerivedData/WDStoreTest-dbsxxdunpvzihagbzjvgylinzzaf/Build/Products/Debug-iphonesimulator/include -I/Users/bdoig/Documents/Projects/boost_1_43_0 -I/Users/bdoig/Library/Developer/Xcode/DerivedData/WDStoreTest-dbsxxdunpvzihagbzjvgylinzzaf/Build/Intermediates/WDStoreTest.build/Debug-iphonesimulator/WDStoreTest.build/DerivedSources/i386 -I/Users/bdoig/Library/Developer/Xcode/DerivedData/WDStoreTest-dbsxxdunpvzihagbzjvgylinzzaf/Build/Intermediates/WDStoreTest.build/Debug-iphonesimulator/WDStoreTest.build/DerivedSources -include /Users/bdoig/Library/Developer/Xcode/DerivedData/WDStoreTest-dbsxxdunpvzihagbzjvgylinzzaf/Build/PrecompiledHeaders/WDStoreTest_Prefix-bwcwseswayysywfpkcwdmibmtjef/WDStoreTest_Prefix.pch -c /Users/bdoig/Dropbox/WData/TopoSort.mm -o /Users/bdoig/Library/Developer/Xcode/DerivedData/WDStoreTest-dbsxxdunpvzihagbzjvgylinzzaf/Build/Intermediates/WDStoreTest.build/Debug-iphonesimulator/WDStoreTest.build/Objects-normal/i386/TopoSort.o

In file included from /Users/bdoig/Dropbox/WData/TopoSort.mm:11: In file included from /Users/bdoig/Dropbox/WData/TopoSort.h:20: In file included from /Users/bdoig/Documents/Projects/boost_1_43_0/boost/graph/topological_sort.hpp:16: In file included from /Users/bdoig/Documents/Projects/boost_1_43_0/boost/graph/depth_first_search.hpp:21: In file included from /Users/bdoig/Documents/Projects/boost_1_43_0/boost/graph/named_function_params.hpp:15: In file included from /Users/bdoig/Documents/Projects/boost_1_43_0/boost/parameter/name.hpp:8: In file included from /Users/bdoig/Documents/Projects/boost_1_43_0/boost/parameter/keyword.hpp:10: In file included from /Users/bdoig/Documents/Projects/boost_1_43_0/boost/parameter/aux_/tag.hpp:8: In file included from /Users/bdoig/Documents/Projects/boost_1_43_0/boost/parameter/aux_/tagged_argument.hpp:10: /Users/bdoig/Documents/Projects/boost_1_43_0/boost/parameter/aux_/arg_list.hpp:127:16:{127:16-127:23}: warning: reference to stack memory associated with local variable 'x' returned [2]

return x.value;

In file included from /Users/bdoig/Dropbox/WData/TopoSort.mm:11: In file included from /Users/bdoig/Dropbox/WData/TopoSort.h:20: In file included from /Users/bdoig/Documents/Projects/boost_1_43_0/boost/graph/topological_sort.hpp:16: In file included from /Users/bdoig/Documents/Projects/boost_1_43_0/boost/graph/depth_first_search.hpp:21: /Users/bdoig/Documents/Projects/boost_1_43_0/boost/graph/named_function_params.hpp:408:19: note: in instantiation of function template specialization 'boost::parameter::aux::empty_arg_list::operator[]<boost::graph::keywords::tag::vertex_index_map, int const>' requested here [2]

()(g, ap[t | 0]);

/Users/bdoig/Documents/Projects/boost_1_43_0/boost/graph/named_function_params.hpp:472:18: note: in instantiation of function template specialization 'boost::detail::override_const_property<boost::parameter::aux::arg_list<boost::parameter::aux::tagged_argument<boost::graph::keywords::tag::visitor, boost::topo_sort_visitor<std::front_insert_iterator<std::deque<int, std::allocator<int> > > > const>, boost::parameter::aux::arg_list<boost::parameter::aux::tagged_argument<boost::graph::keywords::tag::buffer, int const>, boost::parameter::aux::empty_arg_list> >, boost::graph::keywords::tag::vertex_index_map, boost::vertex_index_t, boost::adjacency_list<boost::listS, boost::vecS, boost::directedS, TopoVertexProperty, boost::no_property, boost::no_property, boost::listS> >' requested here [2]

override_const_property(

/Users/bdoig/Documents/Projects/boost_1_43_0/boost/graph/named_function_params.hpp:496:24: note: in instantiation of member function 'boost::detail::color_map_maker_helper<0, boost::adjacency_list<boost::listS, boost::vecS, boost::directedS, TopoVertexProperty, boost::no_property, boost::no_property, boost::listS>, boost::parameter::aux::arg_list<boost::parameter::aux::tagged_argument<boost::graph::keywords::tag::visitor, boost::topo_sort_visitor<std::front_insert_iterator<std::deque<int, std::allocator<int> > > > const>, boost::parameter::aux::arg_list<boost::parameter::aux::tagged_argument<boost::graph::keywords::tag::buffer, int const>, boost::parameter::aux::empty_arg_list> >, boost::default_color_type, int>::make_map' requested here [2]

return helper::make_map(g, white_color, ap[boost::graph::keywords::_color_map | 0], ap);

In file included from /Users/bdoig/Dropbox/WData/TopoSort.mm:11: In file included from /Users/bdoig/Dropbox/WData/TopoSort.h:20: In file included from /Users/bdoig/Documents/Projects/boost_1_43_0/boost/graph/topological_sort.hpp:16: /Users/bdoig/Documents/Projects/boost_1_43_0/boost/graph/depth_first_search.hpp:300:72: note: in instantiation of member function 'boost::detail::color_map_maker<boost::adjacency_list<boost::listS, boost::vecS, boost::directedS, TopoVertexProperty, boost::no_property, boost::no_property, boost::listS>, boost::parameter::aux::arg_list<boost::parameter::aux::tagged_argument<boost::graph::keywords::tag::visitor, boost::topo_sort_visitor<std::front_insert_iterator<std::deque<int, std::allocator<int> > > > const>, boost::parameter::aux::arg_list<boost::parameter::aux::tagged_argument<boost::graph::keywords::tag::buffer, int const>, boost::parameter::aux::empty_arg_list> > >::make_map' requested here [2]

boost::detail::color_map_maker<VertexListGraph, arg_pack_type>::make_map(g, arg_pack),

In file included from /Users/bdoig/Dropbox/WData/TopoSort.mm:11: In file included from /Users/bdoig/Dropbox/WData/TopoSort.h:20: /Users/bdoig/Documents/Projects/boost_1_43_0/boost/graph/topological_sort.hpp:65:5: note: in instantiation of function template specialization 'boost::depth_first_search<boost::adjacency_list<boost::listS, boost::vecS, boost::directedS, TopoVertexProperty, boost::no_property, boost::no_property, boost::listS>, boost::topo_sort_visitor<std::front_insert_iterator<std::deque<int, std::allocator<int> > > >, boost::graph_visitor_t, boost::bgl_named_params<int, boost::buffer_param_t, boost::no_property> >' requested here [2]

depth_first_search(g, params.visitor(TopoVisitor(result)));

/Users/bdoig/Documents/Projects/boost_1_43_0/boost/graph/topological_sort.hpp:71:5: note: in instantiation of function template specialization 'boost::topological_sort<boost::adjacency_list<boost::listS, boost::vecS, boost::directedS, TopoVertexProperty, boost::no_property, boost::no_property, boost::listS>, std::front_insert_iterator<std::deque<int, std::allocator<int> > >, int, boost::buffer_param_t, boost::no_property>' requested here [2]

topological_sort(g, result,

/Users/bdoig/Dropbox/WData/TopoSort.mm:20:3: note: in instantiation of function template specialization 'boost::topological_sort<boost::adjacency_list<boost::listS, boost::vecS, boost::directedS, TopoVertexProperty, boost::no_property, boost::no_property, boost::listS>, std::front_insert_iterator<std::deque<int, std::allocator<int> > > >' requested here [2]

boost::topological_sort(vectorList, std::front_inserter(topo_order));

In file included from /Users/bdoig/Dropbox/WData/TopoSort.mm:11: In file included from /Users/bdoig/Dropbox/WData/TopoSort.h:20: In file included from /Users/bdoig/Documents/Projects/boost_1_43_0/boost/graph/topological_sort.hpp:16: In file included from /Users/bdoig/Documents/Projects/boost_1_43_0/boost/graph/depth_first_search.hpp:21: In file included from /Users/bdoig/Documents/Projects/boost_1_43_0/boost/graph/named_function_params.hpp:15: In file included from /Users/bdoig/Documents/Projects/boost_1_43_0/boost/parameter/name.hpp:8: In file included from /Users/bdoig/Documents/Projects/boost_1_43_0/boost/parameter/keyword.hpp:10: In file included from /Users/bdoig/Documents/Projects/boost_1_43_0/boost/parameter/aux_/tag.hpp:8: In file included from /Users/bdoig/Documents/Projects/boost_1_43_0/boost/parameter/aux_/tagged_argument.hpp:10: /Users/bdoig/Documents/Projects/boost_1_43_0/boost/parameter/aux_/arg_list.hpp:127:16:{127:16-127:23}: warning: reference to stack memory associated with local variable 'x' returned [2]

return x.value;

In file included from /Users/bdoig/Dropbox/WData/TopoSort.mm:11: In file included from /Users/bdoig/Dropbox/WData/TopoSort.h:20: In file included from /Users/bdoig/Documents/Projects/boost_1_43_0/boost/graph/topological_sort.hpp:16: In file included from /Users/bdoig/Documents/Projects/boost_1_43_0/boost/graph/depth_first_search.hpp:21: /Users/bdoig/Documents/Projects/boost_1_43_0/boost/graph/named_function_params.hpp:496:49: note: in instantiation of function template specialization 'boost::parameter::aux::empty_arg_list::operator[]<boost::graph::keywords::tag::color_map, int const>' requested here [2]

return helper::make_map(g, white_color, ap[boost::graph::keywords::_color_map | 0], ap);

In file included from /Users/bdoig/Dropbox/WData/TopoSort.mm:11: In file included from /Users/bdoig/Dropbox/WData/TopoSort.h:20: In file included from /Users/bdoig/Documents/Projects/boost_1_43_0/boost/graph/topological_sort.hpp:16: /Users/bdoig/Documents/Projects/boost_1_43_0/boost/graph/depth_first_search.hpp:300:72: note: in instantiation of member function 'boost::detail::color_map_maker<boost::adjacency_list<boost::listS, boost::vecS, boost::directedS, TopoVertexProperty, boost::no_property, boost::no_property, boost::listS>, boost::parameter::aux::arg_list<boost::parameter::aux::tagged_argument<boost::graph::keywords::tag::visitor, boost::topo_sort_visitor<std::front_insert_iterator<std::deque<int, std::allocator<int> > > > const>, boost::parameter::aux::arg_list<boost::parameter::aux::tagged_argument<boost::graph::keywords::tag::buffer, int const>, boost::parameter::aux::empty_arg_list> > >::make_map' requested here [2]

boost::detail::color_map_maker<VertexListGraph, arg_pack_type>::make_map(g, arg_pack),

In file included from /Users/bdoig/Dropbox/WData/TopoSort.mm:11: In file included from /Users/bdoig/Dropbox/WData/TopoSort.h:20: /Users/bdoig/Documents/Projects/boost_1_43_0/boost/graph/topological_sort.hpp:65:5: note: in instantiation of function template specialization 'boost::depth_first_search<boost::adjacency_list<boost::listS, boost::vecS, boost::directedS, TopoVertexProperty, boost::no_property, boost::no_property, boost::listS>, boost::topo_sort_visitor<std::front_insert_iterator<std::deque<int, std::allocator<int> > > >, boost::graph_visitor_t, boost::bgl_named_params<int, boost::buffer_param_t, boost::no_property> >' requested here [2]

depth_first_search(g, params.visitor(TopoVisitor(result)));

/Users/bdoig/Documents/Projects/boost_1_43_0/boost/graph/topological_sort.hpp:71:5: note: in instantiation of function template specialization 'boost::topological_sort<boost::adjacency_list<boost::listS, boost::vecS, boost::directedS, TopoVertexProperty, boost::no_property, boost::no_property, boost::listS>, std::front_insert_iterator<std::deque<int, std::allocator<int> > >, int, boost::buffer_param_t, boost::no_property>' requested here [2]

topological_sort(g, result,

/Users/bdoig/Dropbox/WData/TopoSort.mm:20:3: note: in instantiation of function template specialization 'boost::topological_sort<boost::adjacency_list<boost::listS, boost::vecS, boost::directedS, TopoVertexProperty, boost::no_property, boost::no_property, boost::listS>, std::front_insert_iterator<std::deque<int, std::allocator<int> > > >' requested here [2]

boost::topological_sort(vectorList, std::front_inserter(topo_order));

In file included from /Users/bdoig/Dropbox/WData/TopoSort.mm:11: In file included from /Users/bdoig/Dropbox/WData/TopoSort.h:20: In file included from /Users/bdoig/Documents/Projects/boost_1_43_0/boost/graph/topological_sort.hpp:16: In file included from /Users/bdoig/Documents/Projects/boost_1_43_0/boost/graph/depth_first_search.hpp:21: In file included from /Users/bdoig/Documents/Projects/boost_1_43_0/boost/graph/named_function_params.hpp:15: In file included from /Users/bdoig/Documents/Projects/boost_1_43_0/boost/parameter/name.hpp:8: In file included from /Users/bdoig/Documents/Projects/boost_1_43_0/boost/parameter/keyword.hpp:10: In file included from /Users/bdoig/Documents/Projects/boost_1_43_0/boost/parameter/aux_/tag.hpp:8: In file included from /Users/bdoig/Documents/Projects/boost_1_43_0/boost/parameter/aux_/tagged_argument.hpp:10: /Users/bdoig/Documents/Projects/boost_1_43_0/boost/parameter/aux_/arg_list.hpp:127:16:{127:16-127:23}: warning: reference to stack memory associated with local variable 'x' returned [2]

return x.value;

In file included from /Users/bdoig/Dropbox/WData/TopoSort.mm:11: In file included from /Users/bdoig/Dropbox/WData/TopoSort.h:20: In file included from /Users/bdoig/Documents/Projects/boost_1_43_0/boost/graph/topological_sort.hpp:16: /Users/bdoig/Documents/Projects/boost_1_43_0/boost/graph/depth_first_search.hpp:301:8: note: in instantiation of function template specialization 'boost::parameter::aux::empty_arg_list::operator[]<boost::graph::keywords::tag::root_vertex, unsigned long const>' requested here [2]

arg_pack[_root_vertex | *vertices(g).first]

In file included from /Users/bdoig/Dropbox/WData/TopoSort.mm:11: In file included from /Users/bdoig/Dropbox/WData/TopoSort.h:20: /Users/bdoig/Documents/Projects/boost_1_43_0/boost/graph/topological_sort.hpp:65:5: note: in instantiation of function template specialization 'boost::depth_first_search<boost::adjacency_list<boost::listS, boost::vecS, boost::directedS, TopoVertexProperty, boost::no_property, boost::no_property, boost::listS>, boost::topo_sort_visitor<std::front_insert_iterator<std::deque<int, std::allocator<int> > > >, boost::graph_visitor_t, boost::bgl_named_params<int, boost::buffer_param_t, boost::no_property> >' requested here [2]

depth_first_search(g, params.visitor(TopoVisitor(result)));

/Users/bdoig/Documents/Projects/boost_1_43_0/boost/graph/topological_sort.hpp:71:5: note: in instantiation of function template specialization 'boost::topological_sort<boost::adjacency_list<boost::listS, boost::vecS, boost::directedS, TopoVertexProperty, boost::no_property, boost::no_property, boost::listS>, std::front_insert_iterator<std::deque<int, std::allocator<int> > >, int, boost::buffer_param_t, boost::no_property>' requested here [2]

topological_sort(g, result,

/Users/bdoig/Dropbox/WData/TopoSort.mm:20:3: note: in instantiation of function template specialization 'boost::topological_sort<boost::adjacency_list<boost::listS, boost::vecS, boost::directedS, TopoVertexProperty, boost::no_property, boost::no_property, boost::listS>, std::front_insert_iterator<std::deque<int, std::allocator<int> > > >' requested here [2]

boost::topological_sort(vectorList, std::front_inserter(topo_order));

3 warnings generated.

[Jeremiah Willcock]

This looks like a Boost.Parameter issue, not a BGL one. The code mentioned in the error message (line 127 of boost/parameter/aux_/arg_list.hpp) does return a reference to a parameter passed in by copy.