Re: Exactly when does autoconf enter cross-compilation mode?

[Nick Bowler]

On 2020-08-22, wferi@niif.hu <wferi@niif.hu> wrote:
> https://www.gnu.org/software/autoconf/manual/autoconf-2.69/html_node/Hosts-and-Cross_002dCompilation.html
> is rather hard to follow in general, but also contains the following
> clear-cut statement: "Now, configure enters cross-compilation mode if
> and only if --host is passed."
>
> However, if I pass in my build architecture Autoconf 2.69 reports:
>
> $ ./configure --host=x86_64-linux-gnu

I imagine that the authors meant to write "only if", rather than
"if and only if" because indeed the statement as written is not true
(the manual immediately goes on to explain the actual behaviour).

Specifying --host alone *may* select cross compilation based on
heuristic (whether the compiler's output can be executed).  As the
manual explains this is fragile and is provided for compatibility
with historical behaviour.

By specifying both --host and --build and then cross compilation mode
is enabled whenever they are different.  This is the preferred method.

Cheers,
  Nick