On Wed, Jun 30, 2004 at 09:25:56AM -0400, David Abrahams wrote:
Christoph Ludwig <cludwig@cdc.informatik.tu-darmstadt.de> writes:
BTW, I was told that if boost/config.hpp is included before any system headers, it will still be able to use _REENTRANT to detect if -pthread was specified on the command line.
That's correct AFAICT, but does not really help. There's already too much code that includes system headers before any boost headers.
If we're in the same situation as Python, which requires "python.h" be included before any system headers, it's a damn shame. I don't understand all the reasons for this situation -- is it POSIX's fault?
The first problem is that the gcc option `-pthread' isn't documented for linux / x86. If you search http://gcc.gnu.org/onlinedocs/gcc-3.4.0/gcc/Option-Summary.html then "pthread" is found only among the RS/6000 and PowerPC options. It's therefore always some guesswork what you can expect from gcc if you compile with pthread support. In particular, it's not documented how you can *detect* pthread support. IIUC POSIX does not (implicitly or explicitly) require any special compiler flags when you compile C code that uses a pthread implementation. I am not even sure whether it is strictly necessary to use the `-pthread' flag if you compile and link such code with gcc or whether it it is mainly a convenience option. (The situation may be different for C++ code if, e.g., the EH code is affected by the pthread support. But POSIX ignores C++, doesn't it?) If I am correct then POSIX cannot require any means to detect *activated* pthread support. I rather think it is a QoI defect of gcc 3.4.
Can we get them to fix this?
If you look at the discussion of gcc PR#11953 (http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11953) then it seems the gcc developers intend to restore the situation we had up to gcc 3.3.x where you could rely on _REENTRANT. That won't happen before gcc 3.4.2, though. Christoph -- http://www.informatik.tu-darmstadt.de/TI/Mitarbeiter/cludwig.html LiDIA: http://www.informatik.tu-darmstadt.de/TI/LiDIA/Welcome.html