There was a bug introduced with the header file generation, so that when you generate both headers and objects in one run and specify path to both header file and object file - then the directory for the object file gets lost in translation.
Something like this, names changed to protect the innocent:
$ gdmd -vdmd -H -Hffoo/bar.di -c foo/bar.d -offoo/bar.o
/usr/bin/gdc -c foo/bar.d -o bar.o -fintfc -fintfc-file=foo/bar.di
Comment #1 by afb — 2007-09-14T03:49:45Z
Created attachment 179
gdmd-interface-output.patch