Hello,
While packaging libdbi for GNU Guix I discovered that passing --docdir=/some/doc/dir had no effect on the location of the installed doc. After digging a bit it seems this is caused by the variable being overriden in Makefile.am:
docdir = $(datadir)/doc/$(PACKAGE)-$(VERSION)
Replacing this by
docdir = @docdir@
fixes the issue.
Thanks,
Maxim