dmd 2.064.2 stuck compiling code?

[michaelc37]

I have an issue where dmd v2.064.2 never finishes compiling 
(hangs)

i'm trying to recompile my patched up fork of qtd 
(https://github.com/michaelc37/qtd) but the code never stops 
compiling (it was compiling with v2.063.2).

i was able to catch the last compiler command line executed using
make SHELL="/bin/bash -x"

/usr/bin/dmd -version=QtdCppShared -I<projectpath>build_dir/build 
-I<projectpath> -I<projectpath>/d2 -O -release -inline -c <lots 
and lots of d source files> 
-of<projectpath>/build_dir/build/CMakeFiles/qtdgui.dir/qtdgui0.o

anyone experiencing this issue using similar command line 
params(-O -release -inline -c)?

any suggestions on how to investigate this further?