I get errors when I try to compile the following bit of code: #include <tr1/unordered_set>
int main() { std::tr1::unordered_set<int> s; const std::tr1::unordered_set<int> &s_ref = s; s_ref.find(27); // Problem is here. return 0; } It appears that hashtable::find_node should be marked as a const member function and isn't. Putting const in (see below) seems to let the thing work, though I haven't tested it rigorously. debian-800:/usr/include/c++/4.0/tr1# diff hashtable-orig hashtable-fixed 863c863 < node* find_node (node* p, const key_type& k, typename hashtable::hash_code_t c); --- > node* find_node (node* p, const key_type& k, typename hashtable::hash_code_t c) const; 1219c1219 < ::find_node (node* p, const key_type& k, typename hashtable::hash_code_t code) --- > ::find_node (node* p, const key_type& k, typename hashtable::hash_code_t code) const Here's the full text of the error I get: [EMAIL PROTECTED]:~/c$ g++-4.0 -v -save-temps -fmessage-length=80 temp.cpp Using built-in specs. Target: i486-linux-gnu Configured with: ../src/configure -v --enable-languages=c,c++,java,f95,objc,ada,treelang --prefix=/usr --enable-shared --with-system-zlib --libexecdir=/usr/lib --enable-nls --without-included-gettext --enable-threads=posix --program-suffix=-4.0 --enable-__cxa_atexit --enable-libstdcxx-allocator=mt --enable-clocale=gnu --enable-libstdcxx-debug --enable-java-gc=boehm --enable-java-awt=gtk --with-java-home=/usr/lib/jvm/java-1.4.2-gcj-4.0-1.4.2.0/jre --enable-mpfr --disable-werror --enable-checking=release i486-linux-gnu Thread model: posix gcc version 4.0.1 (Debian 4.0.1-2) /usr/lib/gcc/i486-linux-gnu/4.0.1/cc1plus -E -quiet -v -D_GNU_SOURCE temp.cpp -mtune=i486 -fmessage-length=80 -fpch-preprocess -o temp.ii ignoring nonexistent directory "/usr/local/include/i486-linux-gnu" ignoring nonexistent directory "/usr/include/i486-linux-gnu" #include "..." search starts here: #include <...> search starts here: /usr/lib/gcc/i486-linux-gnu/4.0.1/../../../../include/c++/4.0.1 /usr/lib/gcc/i486-linux-gnu/4.0.1/../../../../include/c++/4.0.1/i486-linux-gnu /usr/lib/gcc/i486-linux-gnu/4.0.1/../../../../include/c++/4.0.1/backward /usr/local/include /usr/lib/gcc/i486-linux-gnu/4.0.1/include /usr/include End of search list. /usr/lib/gcc/i486-linux-gnu/4.0.1/cc1plus -fpreprocessed temp.ii -quiet -dumpbase temp.cpp -mtune=i486 -auxbase temp -version -fmessage-length=80 -o temp.s GNU C++ version 4.0.1 (Debian 4.0.1-2) (i486-linux-gnu) compiled by GNU C version 4.0.1 (Debian 4.0.1-2). GGC heuristics: --param ggc-min-expand=47 --param ggc-min-heapsize=32148 /usr/lib/gcc/i486-linux-gnu/4.0.1/../../../../include/c++/4.0.1/tr1/hashtable: In member function 'typename std::tr1::hashtable<Key, Value, Allocator, ExtractKey, Equal, H1, H2, H, RehashPolicy, cache_hash_code, mutable_iterators, unique_keys>::const_iterator std::tr1::hashtable<Key, Value, Allocator, ExtractKey, Equal, H1, H2, H, RehashPolicy, cache_hash_code, mutable_iterators, unique_keys>::find(const Key&) const [with Key = int, Value = int, Allocator = std::allocator<int>, ExtractKey = Internal::identity<int>, Equal = std::equal_to<int>, H1 = std::tr1::hash<int>, H2 = Internal::mod_range_hashing, H = Internal::default_ranged_hash, RehashPolicy = Internal::prime_rehash_policy, bool cache_hash_code = false, bool mutable_iterators = false, bool unique_keys = true]': temp.cpp:9: instantiated from here /usr/lib/gcc/i486-linux-gnu/4.0.1/../../../../include/c++/4.0.1/tr1/hashtable:1135: error: passing 'const std::tr1::hashtable<int, int, std::allocator<int>, Internal::identity<int>, std::equal_to<int>, std::tr1::hash<int>, Internal::mod_range_hashing, Internal::default_ranged_hash, Internal::prime_rehash_policy, false, false, true>' as 'this' argument of ' typename std::tr1::hashtable<Key, Value, Allocator, ExtractKey, Equal, H1, H2, H, RehashPolicy, cache_hash_code, mutable_iterators, unique_keys>::node* std::tr1::hashtable<Key, Value, Allocator, ExtractKey, Equal, H1, H2, H, RehashPolicy, cache_hash_code, mutable_iterators, unique_keys>::find_node(Internal::hash_node<Value, cache_hash_code>*, const Key&, typename std::tr1::hashtable<Key, Value, Allocator, ExtractKey, Equal, H1, H2, H, RehashPolicy, cache_hash_code, mutable_iterators, unique_keys>::hash_code_t) [with Key = int, Value = int, Allocator = std::allocator<int>, ExtractKey = Internal::identity<int>, Equal = std::equal_to<int>, H1 = std::tr1::hash<int>, H2 = Internal::mod_range_hashing, H = Internal::default_ranged_hash, RehashPolicy = Internal::prime_rehash_policy, bool cache_hash_code = false, bool mutable_iterators = false, bool unique_keys = true]' discards qualifiers -- Summary: Const-correctness issue in TR1 hashtable Product: gcc Version: 4.0.1 Status: UNCONFIRMED Severity: minor Priority: P3 Component: libstdc++ AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: evilalias at hotmail dot com CC: gcc-bugs at gcc dot gnu dot org GCC build triplet: i486-linux-gnu GCC host triplet: i486-linux-gnu GCC target triplet: i486-linux-gnu http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23053