_SOURCES variable, files that are not translation units

[Mike Mattie]

automake mailing list,

The _SOURCES variable makes a poor assumption, that the .c files
listed are translation units. It is permissable though uncommon to
create .c files that are included into a translation unit to break up
a source file for organizational purposes. Automake's assumption about
the .c  extension being a translation unit has forced me to place
these files in _DEPENDANCIES
which breaks the tags target and creation of a dist file (another
issue). Is there something I missed in the docs or would a patch be
required to correct this ?