> [ruby-dev:18109] mkmf.rb and extmk.rb
> 
>   WATANABE Hirofumi raise the issue of mkmf.rb and extmk.rb.

As long as people are looking at mkmf.rb for other reasons, I'd like to 
raise an issue as well. The mkmf.rb code already recognizes ".cxx" as a 
valid source extension for C++ source files but the suffix rules that it 
writes into the generated Makefile:

	.cxx.o:
		$(CXX) $(CXXFLAGS) $(CPPFLAGS) -c -o $@ $<

assumes that ".cxx" is in make's default list of known suffixes. For the 
version of GNU make that ships with Red Hat Linux 7.3 (make-3.79.1) this 
is *not* the case, and so "make" will fail for this Makefile.

The solution is to add ".cxx" to the list of known suffixes by inserting 
a rule for the special target .SUFFIXES, somewhere near the top of the 
Makefile, e.g.

	.SUFFIXES: .cxx

I can supply a patch to mkmf.rb if it would help, but I think it's 
fairly self-explanatory. If more background on this stuff is useful, 
please see:

	http://www.gnu.org/manual/make/html_node/make_107.html

Thanks,

Lyle