[Bug d/107101] d: Add stub for object module when libphobos is not compiled, or supported

[ibuclaw at gdcproject dot org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107101

--- Comment #1 from Iain Buclaw <ibuclaw at gdcproject dot org> ---
This also affects when compiling with `-nostdinc`.