Re: Recap and patch to deprecating cross-compiler stuff

[Eric Sunshine]

On Mon, 22 Mar 2004 05:51:04 -0500, Bonzini wrote:
> Here is an updated patch that removes the deprecation, but
> still changes the other bits.

It looks good.

> Therefore, if you mean to override the result of
> @command{config.guess}, prefer @option{--build} over
> @option{--host}.  @option{--host} does not override the name of the
> build system type as it did in Autoconf versions up to 2.60, so you
> do not need to specify @code{--build} whenever you specify
> @code{--host}.

Slightly more idiomatic:

"Therefore, if you need to override the result of @command{config.guess} (if  
it guessed the build type incorrectly, for instance), use the  
@option{--build} option.  For transitional reasons, in Autoconf versions up  
to 2.60, @option{--host} overrode the name of the build type, so it was  
necessary to specify both @option{--build} and @option{--host} when  
cross-compiling; however, as of 2.60, @option{--host} no longer influences  
@option{--build}."

> @command{configure} will also accept a system type as an option by
> itself.  Such an option is equivalent to @code{--build} and will
> override the defaults for build, host, and target system types.
> The following configure statement will configure a program that
> will run on address@hidden/alpha, and will be used for example if
> @command{config.guess} misdetects the build platform:

"...and target system types. For example, if @command{config.guess} fails to  
detect that the build platform is address@hidden/alpha, the following  
configure command can be used:"

> Also, in Autoconf 2.13 and before, the variables @code{build},
> @code{host}, and @code{target} had a different semantics before and
> after the invocation of @code{AC_CANONICAL_BUILD} etc.  Now, the
> argument of @option{--build} is strictly copied into
> @code{build_alias}, and is left empty otherwise.  After the
> @code{AC_CANONICAL_BUILD}, @code{build} is set to the canonicalized
> build type.  To ease the transition, before, its contents is the
> same as that of @code{build_alias}.  Do @emph{not} rely on this
> broken feature, though it causes little trouble and seems unlikely
> to go away soon.

"...empty otherwise.  After the invocation of @code{AC_CANONICAL_BUILD},  
@code{build} is set to the canonicalized build type.  To ease the transition  
from earlier Autoconf versions, before @code{AC_CANONICAL_BUILD} is invoked,  
@code{build} is the same as @code{build_alias}, however, do @emph{not} rely  
on this broken feature..."

> if test "x$build_alias" = "x$host_alias"; then
> AC_MSG_WARN([You specified --host, so cross-compile mode will be used.
> If you wanted to set the --build type, you do not need --host.])

"If you simply wanted to set the --build type, ..."

-- ES