GNAT - filename/unitname question

Consider the following source file:

filename.adb
------------
  procedure unitname is
  begin
     ...
  end unitname;

Compiling it gives a warning:

  filename.adb:1:11: warning: file name does not match unit name, should
  be "unitname.adb"

And generates the files:

  filename.ali
  filename.o


The question is: is there a gcc switch or GNAT pragma to force the compiler to use the unitname for the object files? To have:

  unitname.ali
  unitname.o

instead of filename.* object files.

I've read the GNAT documentation for gcc switches and pragmas, but found nothing useful.

Thanks,
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