Here is my environment. % g++ -v Using built-in specs. Target: i686-apple-darwin9 Configured with: /var/tmp/gcc/gcc-5483~1/src/configure --disable-checking -enable-werror --prefix=/usr --mandir=/share/man --enable-languages=c,objc,c++,obj-c++ --program-transform-name=/^[cg][^.-]*$/s/$/-4.0/ --with-gxx-include-dir=/include/c++/4.0.0 --with-slibdir=/usr/lib --build=i686-apple-darwin9 --with-arch=apple --with-tune=generic --host=i686-apple-darwin9 --target=i686-apple-darwin9 Thread model: posix gcc version 4.0.1 (Apple Inc. build 5483) Boost 1.35.0 (also produced same issue with Boost 1.34.1) Here is the code. 1 #include <boost/lambda/lambda.hpp> 2 #include <boost/lambda/construct.hpp> 3 #if defined(INCLUDE_BOOST_BIND) 4 # include <boost/bind.hpp> 5 #endif 6 #include <iostream> 7 #include <iterator> 8 #include <algorithm> 30 31 int main() 32 { 33 using namespace std; 34 using namespace boost::lambda; 35 36 typedef std::istream_iterator<int> in; 37 std::for_each(in(std::cin), in(), std::cout << (_1 * 3) << " " ); 76 } (The astute reader will note discontinuity in the line numbering. This is a playground for my exploration with boost. All elided lines are #if 0'ed. Here is the compile command line and the compilation error, both edited for clarity. g++ -c -g -Wall -fexceptions -DINCLUDE_BOOST_BIND -I/path/to/boost-1.35.0/include main.cpp -o main.o main.cpp: In function 'int main()': main.cpp:37: error: '_1' was not declared in this scope I have seen these related articles from the archives of this list but none of the suggestions eliminated the error. I added the inclusion of boost/lambda/construct.hpp per one of the suggestions there. Its inclusion or exclusion doesn't change the behavior. http://thread.gmane.org/gmane.comp.lib.boost.user/35128 http://thread.gmane.org/gmane.comp.lib.boost.user/16630 http://thread.gmane.org/gmane.comp.lib.boost.user/16887 As you may imagine, the elided (and commented out) lines contain actual uses of boost/bind.hpp but it is a mystery to me that simple inclusion of a header file would cause otherwise working code to stop compiling. This compile command (same as above but with -D removed): g++ -c -g -Wall -fexceptions -I/path/to/boost-1.35.0/include main.cpp -o main.o runs to completion and the subsequent link is successful. Any ideas? Thanks in advance, Ken