I come from a Java background, using mostly just IDEs to handle builds, so I'm very confused about how all this linking is done.

I installed GDC from source into /opt/gdc, and I'm trying to build a simple program using SCons.

After a lot of experimenting, I came up with this SConstruct file:

DefaultEnvironment(DC='/opt/gdc/bin/gdmd')
Program('helloworld',
        'main.d',
        LIBPATH='/opt/gdc/lib64',
        LIBS='gphobos2')

When I run scons, these commands are executed:

/opt/gdc/bin/gdmd -I. -c -ofmain.o main.d
Use of uninitialized value $ENV{"HOME"} in concatenation (.) or string at /opt/gdc/bin/gdmd line 186.
gcc -o helloworld main.o -L/opt/gdc/lib64 -lgphobos2

then, I get a bunch of undefined reference errors like this:

/opt/gdc/lib64/libgphobos2.a(monitor_.o): In function `_STI_monitor_staticctor':
/home/ed/code/gdc/gdc/dev/gcc-4.6.2/objdir/x86_64-unknown-linux-gnu/libphobos/../../../libphobos/rt/monitor_.d:191: undefined reference to `pthread_mutexattr_init'
/home/ed/code/gdc/gdc/dev/gcc-4.6.2/objdir/x86_64-unknown-linux-gnu/libphobos/../../../libphobos/rt/monitor_.d:192: undefined reference to `pthread_mutexattr_settype'

I also don't know why it's saying these files are in /home/ed/... That's where I compiled them from before installing to /opt, but they are not there anymore.

The /opt/gdc directory structure is:

$ ls /opt/gdc
bin  include  lib  lib32  lib64  libexec  share

So, what's going on here, and how do I go about building the helloworld program?

Nevermind, I think I figured it out. Looks like libgphobos2 depends on libm, libpthread, and librt. So, changing the SConstruct file to:

DefaultEnvironment(DC='/opt/gdc/bin/gdmd')
Program('helloworld',
        'main.d',
        LIBPATH=['/opt/gdc/lib64','/usr/lib'],
        LIBS=['gphobos2','m','pthread','rt'])

Solves the problem. Though, if there's a better way to do things, feel free to let me know.