When trying to build Fossil on Haiku (ticket 084eedc010), I run into a problem with the Makefile. The following syntaxes do not seem to be supported by GNU Make 3.82:

HOST_OS :sh = uname -s

and

HOST_OS = $(uname -s:sh)

The following does work (but breaks things for other make variants, I assume):

HOST_OS = $(shell uname -s)