what's this Error: corrupt MS Coff object module

[mw]

I got this error, when build with 
VisualD-v1.0.1-dmd-2.093.1-ldc2-1.23.0.exe

dmd:

lib\unit-threaded_property.lib: Error: corrupt MS Coff object 
module 
obj\debug\dummy\dummy\dummy\dummy\dummy\dummy\unit-threaded_property\..\..\..\..\..\..\Users...\AppData\Local\dub\packages\unit-threaded-1.0.4\unit-threaded\subpackages\property\source\unit_threaded\randomized\benchmark.obj 320
lib\unit-threaded_property.lib: Error: corrupt MS Coff object 
module 
obj\debug\dummy\dummy\dummy\dummy\dummy\dummy\unit-threaded_property\..\..\..\..\..\..\Users...\AppData\Local\dub\packages\unit-threaded-1.0.4\unit-threaded\subpackages\property\source\unit_threaded\randomized\package.obj 320
Building lib\unit-threaded_property.lib failed!


(I didn't add package unit-threaded myself, guess it's indirectly 
pulled in by some other packages.)

How to fix this Coff object issues?

(BTW, why there are so many \dummy\... dirs?)