bug#19111: 25.0.50; 32 bits temacs.exe is linked with wrong image-base when built on 64 bit Windows host

[Eli Zaretskii]

> From: Óscar Fuentes <ofv@wanadoo.es>
> Cc: 19111@debbugs.gnu.org
> Date: Thu, 20 Nov 2014 19:30:37 +0100
> 
> > Sorry, it doesn't.  You say that $MSYSTEM is set to either MINGW32 or
> > MINGW64, depending on whether 32-bit or 64-bit toolset is used.  But
> > how does MSYS2 know which toolset you are going to use to compile a
> > program?  How do you communicate that to MSYS2?
> 
> It is set automatically by the .bat file that starts the MSYS2 shell.
> There is a .bat that sets $MSYSTEM, paths, etc for MINGW32, other for
> MINGW64 and other for MSYS.

Is that reliable enough?  What if someone does these things by hand,
without relying on batch files?

> In the end, the user must ensure that $MSYSTEM matches the toolset he is
> going to use.

Why?  We don't even use $MSYSTEM in the configure script (on master),
and neither do other GNU packages.

> > In any case, what I suggest to do is correct the triplet,
> > automatically, after uname guesses it, if we find that it is wrong for
> > "the toolset about to be used", whatever that means.
> 
> How do we know that the triplet is wrong?

One way is to run the compiler, I guess.

> Another solution is to get the --host/--build triplet from `gcc -v' (use
> the `--target=...' part.

Yes, something like that.

> I don't know how it is supposed to deal with the case of the user
> setting those parameters explicitly, although I can't think of a
> valid reason for setting --host/--build to something different from
> the `gcc -v' --target, since Emacs does not support cross-compiling.

If the user sets the triplet, it should be obeyed.  If it's incorrect,
that's the user's problem.

> I understand your concern: `configure' can use the triplet anywhere and
> hence it is important that it is correct.

Yes, exactly.

Could you propose a patch along these lines?