Re: Partial autoconf transition thoughts

["Maciej W. Rozycki" <macro@ds2.pg.gda.pl>]

On 10 Jun 2003, Alexandre Oliva wrote:

> >  Well, if I specify --host, I mean I want to use a different alias than
> > the one that is expanded by config.sub.
> 
> --host has absolutely nothing to do with config.sub.  --host defaults

 Has it?  AFAIR, whatever you specify as --host gets passed through
config.sub before it gets assigned to $host (I'm prepending that "$" now
to disambiguate variable references).

> to --build, that defaults to the output of config.guess.  If you want
> to override --build, just do it, and it will be propagated to host as

 But it will be substituted by config.sub first and the original value 
won't be propagated to $host_alias, will it?

> well.  If you mean to specify different --build and --hosts, that's a
> cross.  If you specify --build and --host and they're identical,
> that's a native for now, but it'll eventually be a cross because
> there's no point in specifying --host if you don't want a cross.

 Agreed, as long as there is a way to have $host_alias and $target_alias
set up as desired. 

> > The change is not purely internal
> > to the compilation process -- there are examples, binutils and gcc
> > inclusive, where this alias gets propagated to file names, e.g. as a
> > prefix to executables or as a name of the tooldir.
> 
> That's --target, something entirely different.

 Hmm:

$ locate libbfd-2.13.2.1.so
/usr/i386-linux/mips64el-linux/lib/libbfd-2.13.2.1.so
/usr/i386-linux/mipsel-linux/lib/libbfd-2.13.2.1.so
/usr/lib/libbfd-2.13.2.1.so
$ 

Where does that "i386-linux" above come from, then?  That's nitpicking
anyway -- the same comment applies to $target_alias equally well.

> >  I'd like to see this capability preserved, not necessarily exactly the
> > way it's being done now.  One possibility for host_alias and also
> > target_alias is to default to build_alias and host_alias instead of host
> > and target, respectively, as it happens now. 
> 
> Huh?  Where is it that host_alias defaults to build or build_alias?
> In autoconf, it defaults to neither.  If --host is not specified,
> host_alias remains blank, not the same as build_alias, not the same as

 That's an internal implementation detail -- I simplified to avoid
complicated dissertations.  AFAIK, if $host_alias is non-empty it is its
value that gets propagated to file names, otherwise the value of $host is
used (ditto about $target_alias and $target).  This is what I mean by
stating "$host_alias defaults to $host" (i.e. I am not really interested
in how autoconf handles ${build,host,target}_alias" internally, but in the
end result visible to a user).  And that's probably the source of
confusion.  And I am not sure why it needs to be done in such a
complicated way. 

> nonopt, not the same as the output of config.guess.  Nathan was kind
> enough to write macros that do exactly what you want, AFAICT, setting
> {build,host,target}_noncanonical, which is what we'd now use for what
> we used to use {build,host,target}_alias, whose meaning is slightly
> different in autoconf 2.5x.  I.e., it does what you already.

 Well, this is probably an option, but I don't know why such a
complication necessary.  Have you seen the dependency graphs I sent
yesterday?  I believe my proposal is the simplest solution. 

-- 
+  Maciej W. Rozycki, Technical University of Gdansk, Poland   +
+--------------------------------------------------------------+
+        e-mail: macro@ds2.pg.gda.pl, PGP key available        +