Creating two files:
==== t1.cpp ===
#include <tr1/unordered_map>
std::tr1::unordered_map<int,int> map1;
int main() {}
==== t2.cpp ====
#include <tr1/unordered_map>
std::tr1::unordered_map<int, float> map;
int t2(int i) { return 0; }
=============
compiling them with
g++ -Wall t1.cpp t2.cpp
leads to compiler output:
t2.o:(.bss+0x20): multiple definition of `std::tr1::placeholders::(anonymous
namespace)::_10'
t1.o:(.bss+0x20): first defined here
t2.o:(.bss+0x21): multiple definition of `std::tr1::placeholders::(anonymous
namespace)::_9'
t1.o:(.bss+0x21): first defined here
t2.o:(.bss+0x22): multiple definition of `std::tr1::placeholders::(anonymous
namespace)::_8'
t1.o:(.bss+0x22): first defined here
t2.o:(.bss+0x23): multiple definition of `std::tr1::placeholders::(anonymous
namespace)::_7'
t1.o:(.bss+0x23): first defined here
t2.o:(.bss+0x24): multiple definition of `std::tr1::placeholders::(anonymous
namespace)::_6'
t1.o:(.bss+0x24): first defined here
t2.o:(.bss+0x25): multiple definition of `std::tr1::placeholders::(anonymous
namespace)::_5'
t1.o:(.bss+0x25): first defined here
t2.o:(.bss+0x26): multiple definition of `std::tr1::placeholders::(anonymous
namespace)::_4'
t1.o:(.bss+0x26): first defined here
t2.o:(.bss+0x27): multiple definition of `std::tr1::placeholders::(anonymous
namespace)::_3'
t1.o:(.bss+0x27): first defined here
t2.o:(.bss+0x28): multiple definition of `std::tr1::placeholders::(anonymous
namespace)::_2'
t1.o:(.bss+0x28): first defined here
t2.o:(.bss+0x29): multiple definition of `std::tr1::placeholders::(anonymous
namespace)::_1'
t1.o:(.bss+0x29): first defined here
t2.o:(.bss+0x2a): multiple definition of `std::tr1::(anonymous
namespace)::ignore'
t1.o:(.bss+0x2a): first defined here
t2.o:(.data+0x0): multiple definition of `_ZN8Internal1XIXT_EE8n_primesE'
t1.o:(.data+0x0): first defined here
==========
Thus preventing use of two unordered_map's in a single application.
g++ -v:
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
--without-included-gettext --enable-threads=posix --enable-nls
--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 --enable-gtk-cairo
--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 4.0.2 (Debian 4.0.2-2)
--
Summary: tr1::unordered_map duplicate symbols (not extern?)
Product: gcc
Version: 4.0.2
Status: UNCONFIRMED
Severity: normal
Priority: P2
Component: c++
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: maarten dot keijzer at gmail dot com
GCC host triplet: Linux version 2.6.10
GCC target triplet: g++ 4.0.2
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24389
