Re: Installation proposal

[Mark Mitchell <mark at codesourcery dot com>]

--On Wednesday, February 27, 2002 11:14:11 AM -0800 Jim Wilson 
<wilson@redhat.com> wrote:

> There are 3 prefixes not 1.  This scheme still needs to work even if
> prefix != exec_prefix != local_prefix.

OK.  Must we really keep all of these?

In any case, local_prefix should not be a problem; that's an absolute
path.  Wherever we drop the compiler binaries, this will be the same.

So, I think it's really a question of whether we need exec_prefix.
I can see why we wanted this, but I'm not convinced that we should
still want it.  (Sometimes, we say "I can imagine this feature being
useful" or even "I use this feature and I like it" and forget that
this is not the same as "this feature is, on balance, better than
its absence.")

If we must keep exec_prefix, we can maybe keep it by always setting
exec_prefix to "install/exec_prefix" and then at install-time,
copying the files from "install/exec_prefix" to the right place.  This
will maybe not work depending on how the driver thinks it is going
to find things in the exec_prefix.

It sounds to me like exec_prefix probably defeats the
location-independence of the compiler driver, which is not good,
in addition to the fact that it probably makes exec_prefix
incompatible with the scheme I proposed.

> As David Edelsohn mentioned, there could be problems if you have a
> previous installed tree with the same prefix.  The tree being tested may
> accidentally use stuff from the install tree if we aren't manually using
> -B/-L/-I/etc overrides.

That would be a bug; the stuff to find the compiler and use its
current path should prevent this.

It's not that it might not happen, just that it shouldn't.

> This could cause problems with builds using combined
> binutils/gcc/newlib/etc source trees.

Why?  The would get their prefix set to the same prefix ("install") as
GCC, and then they would get installed there.  Does GCC's configury
not look for "as" and such in the prefix in which it will finally be
installed?

-- 
Mark Mitchell                mark@codesourcery.com
CodeSourcery, LLC            http://www.codesourcery.com