import std.parallelism;

void foo()
{}

void main() {
   auto t = task!foo();
   t.executeInNewThread(1);
}

Output from gdb:

Program received signal SIGSEGV, Segmentation fault.
0x0000003016e0839b in pthread_getschedparam () from /lib64/libpthread.so.0
Missing separate debuginfos, use: debuginfo-install glibc-2.12-1.80.el6_3.5.x86_64
(gdb) bt
#0  0x0000003016e0839b in pthread_getschedparam () from /lib64/libpthread.so.0
#1  0x0000000000458cd0 in core.thread.Thread.priority() ()
#2  0x0000000000000000 in ?? ()

Compiling with -m32 causes the same issue with better backtrace:

Program received signal SIGSEGV, Segmentation fault.
0x0011844d in pthread_getschedparam () from /lib/libpthread.so.0
Missing separate debuginfos, use: debuginfo-install glibc-2.12-1.80.el6_3.5.i686
(gdb) bt
#0  0x0011844d in pthread_getschedparam () from /lib/libpthread.so.0
#1  0x08095253 in core.thread.Thread.priority() ()
#2  0x08092f1e in std.parallelism.TaskPool.__ctor() ()
#3  0x080873df in std.parallelism.Task!(foo).Task.executeInNewThread (this=0xf7ee5fe0, priority=1) at /usr/include/d/dmd/phobos/std/parallelism.d:753
#4  0x08086ae1 in D main () at deneme.d:102585
#5  0x0808f564 in rt.dmain2.main() ()
#6  0x0808f074 in rt.dmain2.main() ()
#7  0x0808f5a6 in rt.dmain2.main() ()
#8  0x0808f074 in rt.dmain2.main() ()
#9  0x0808f024 in main ()