Re: [Trunk] patch for GNU-friendly gengtype

[Paolo Bonzini <bonzini at gnu dot org>]

On 06/21/2010 08:13 AM, Laurynas Biveinis wrote:
> 2010/6/21 Basile Starynkevitch<basile@starynkevitch.net>:
> > Sorry, I wrote something unclear. What I want, is to have gengtype
> > accept a --version program argument. I first tried to link version.o
> > inside build/gengtype, but doing that did add a circular dependency,&
> > make issued a warning about that.
>
> Exactly. Why is this happening? The circular dependency means that
> there is a pre-existing version.o dependency on build/gengtype, so
> when you add the dependency the other way around, you complete the
> circle. But this pre-existing dependency is IMHO wrong, version.o
> should not depend on build/gengtype, or there is something else going
> on with Makefile which I don't understand.

# In order for parallel make to really start compiling the expensive
# objects from $(OBJS-common) as early as possible, build all their
# prerequisites strictly before all objects.
$(ALL_HOST_OBJS) : | $(generated_files)

In any case, using version.o would break cross-compilation.  You need to 
add a build/version.o and link _that_ with gengtype.  Rules to compile 
build/version.o using the same compiler as gengtype are implicitly used.

Paolo