Date: Mon, 3 Jun 2002 15:49:13 +0800 From: "David Xu" <davidx@viasoft.com.cn> To: "Terry Lambert" <tlambert2@mindspring.com>, <jos@catnook.com> Cc: <freebsd-hackers@FreeBSD.ORG> Subject: Re: Improving GNU make compatibility in BSD make (+ patch) Message-ID: <008201c20ad3$282b0380$ef01a8c0@davidwnt> References: <20020531024250.GA90997@lizzy.catnook.com> <3CF73679.A5AB7886@mindspring.com>
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The reason that autoconf & automake can only run under gmake is
gmake will re-read included file if the included file itself is modified by
some rules. BSD make does not! so they do not work with BSD make.
for example:
DEP_FILES = aaa.d bbb.d ccc.d
$(DEP_FILES): %.d : %.cpp
@echo "Generating auto dependency for $<"
@$(SHELL) -ec '$(GXX) -MM $(CXXFLAGS) $< \
| sed '\''s/\($*\)\.o[ :]*/\1.o $@ : /g'\'' > $@; \
[ -s $@ ] || rm -f $@'
-include $(DEP_FILES)
when aaa.d and bbb.d and ccc.d are updated, gmake will re-readed it in while
BSD make not.
in this example, if I use BSD make, I must first create target "depend" in Makefile and
run the stupid "make depend" command everytime I modified my source code,
with gmake, I can always run "make" without additional steps and it will generates
auto-depend rule before compiling real source code.
David Xu
----- Original Message -----
From: "Terry Lambert" <tlambert2@mindspring.com>
To: <jos@catnook.com>
Cc: <freebsd-hackers@FreeBSD.ORG>
Sent: Friday, May 31, 2002 4:38 PM
Subject: Re: Improving GNU make compatibility in BSD make (+ patch)
> Jos Backus wrote:
> > So BSD make interpreting either `$^' or `$+' as its own `$>' would improve
> > compatibility with GNU make Makefiles. I am just not sure which of the two GNU
> > make variables maps better to our `$>'. This patch implements the former:
>
> The biggest problem with GNU make that I've seen is re-expansion
> of variable variables.
>
> The suggested fix doesn't address that, so it won't fix the most
> common "compatability problem".
>
> If we are going to evolve make into gmake (not a good idea, IMO),
> then probably the place to start is "any port that requires gmake"
> to get it working under "make".
>
> I'm not sure, but I believe the other BSD's, and "OpenPorts" have
> modified "make" syntax somewhat. It's probably a good idea to keep
> compatability with options in the "OpenPorts" camp, more than any
> other, if it ever evolves to fulfill its potential properly.
>
> I really hate that many autoconf/automake scripts generate code
> that can ony be run by gmake, and sometimes also requires that
> /bin/sh actually be "bash" instead of "sh".
>
> It also occurs to me (from experience with "perl"), that in any
> language where it's posible to do something in more than one way,
> it is then impossible to differentiate "the right way" from "the
> wrong way". 8-(.
>
> -- Terry
>
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