Re: make: avoid breaking backwards compatability

[Alan Barrett <apb%cequrux.com@localhost>]

On Fri, 05 Sep 2014, Jarmo Jaakkola wrote:
> On Fri, Sep 05, 2014 at 12:36:18AM +0200, Alan Barrett wrote:
> > We do want to consistently override on a file by file 
> > basis. [...]
>
> Please somebody tell me why are you people so dead set against 
> using a directory in the dependency?  It would explicitly remove 
> all ambiguity and would not rely on implementation specific 
> tricks.

If we were designing a build system with a version of make that 
behaved in the new way, perhaps we would have done that.  But we 
are not designing a new build system; we already have a build 
system that has grown around make's old behaviour.  We can change 
NetBSD's build system, but third parties may rely on the same old 
behaviour, and we can't break it lightly.

> What is wrong with (not intended to be syntactically correct):
>
>    .if arch = arch1
>    exe: arch1/foo.o
>    .elif arch = arch2
>    exe: arch2/foo.o
>    .else
>    exe: foo.o
>    .fi
>
> or
>
>    .if exists(${arch}/foo.S)
>    exe: ${arch}/foo.o
>    .else
>    exe: foo.o
>    .fi

Those would work fine, but they are not what we have.

--apb (Alan Barrett)