Problem still happens with gdc 4.9 :-( gdc -I. -O3 -c -o pi_parallelReduce.o pi_parallelReduce.d /usr/include/d/4.9/std/parallelism.d: In member function 'reduce': /usr/include/d/4.9/std/parallelism.d:2630: error: cannot access frame of function 'main' from 'reduce' scons: *** [pi_parallelReduce.o] Error 1