On Tue, Oct 05, 2004 at 03:05:13PM +0200, Markus Sch?pflin wrote:
When compiling the smart pointer tests with gcc 3.4.2 on Tru64, two tests fail with an error message. (See http://tinyurl.com/4jngu )
As far as I can see, the shared pointer implementation at some point includes the "pthread.h" system header file but gcc on Tru64 requires that -pthread must be specified on the command line when including this header file.
When running this test with gcc 3.4.2 on Linux the file "pthread.h" is also included but gcc doesn't require the addition of -pthread in the command line on this platform.
This leads to the question whether it is ok to include "pthread.h" without specifying -pthread on the command line. Does anyone know an answer to this?
Short answer: yes, it's OK. Long answer: On Linux, with GCC, yes, it's fine. libstdc++ does this itself. When configured to use pthreads (*) the library includes gthr-posix.h, which unconditionally includes pthread.h At link time, if -pthread wasn't given, the pthread_xxx() symbols declared in pthread.h aren't found and so the linker falls back to weak symbols defined in the libstdc++ library (which are just stubs that do nothing). I'm not so sure about other POSIX platforms, just Linux. jon (*) N.B. configuring the compiler to use threads does NOT mean you always compile with pthreads, it means you have the _option_ of compiling with -pthread. If the compiler isn't configured to use threads then you can't use -pthread at all. -- "Live fast, die old, and make very sure everyone knows you were there." - Alan Cox