Re: cross compiling and autoconf's host vs build (vs target)

Sorry, yes I forgot US thanksgiving.  I've been trying to check if my
posts got through by looking at:
  https://groups.google.com/forum/#!forum/mozilla.dev.tech.nspr
but it seems to only show half of them. Now that I know that they are
getting out, I'll just ignore the list.

Anyway, like you suggest, I'll submit a PR.

Andrew


On 2 December 2015 at 12:19, Wan-Teh Chang <[email protected]> wrote:
> Hi Andrew,
>
> I saw both this post and a follow-up post of yours regarding the same
> topic. The reason for the late reply is that last Thursday and Friday
> were Thanksgiving holidays in the US.
>
> On Thu, Nov 26, 2015 at 10:49 AM, Andrew Cagney <[email protected]> wrote:
>> The autoconf 2.13 to 2.50 transition, er, "cleaned up" cross
>> compilation and, in the process, "clarified" the meaning of "host",
>> "build" and "target".
>>
>> For instance, I can specify:
>>
>> ./configure --host=m68k-uclinux-linux --build=i686-pc-linux-gnu
>> --target=m68k-uclinux-linux ...
>>
>> to cross compile npsr (--host and host!=build trigger the cross compile):
>>
>> checking build system type... i686-pc-linux-gnu
>> checking host system type... m68k-uclinux-linux-gnu
>> checking target system type... m68k-uclinux-linux-gnu
>>
>> However, for nspr, this didn't work.  Looking at configure.in, it
>> seems to still have traces of the old 2.13 conventions (mixing "$host"
>> and "$build").  For instance:
>>
>> -if test "$target" != "$host"; then
>> -    echo "cross compiling from $host to $target"
>> +if test "$target" != "$build"; then
>> +    echo "cross compiling from $build to $target"
>>
>> which is changed by the below patch.
>>
>> However, tread carefully, I find the way this all hangs together
>> quickly gets messy and confusing (details are in "Hosts and
>> Cross-Compilation" section in autoconf's documentation).
>
> Thank you for the patch. It is a known problem that NSPR's
> configure.in script doesn't follow the current autoconf convention for
> cross compilation. I noticed this when I ported configure.in from
> autoconf 2.13 to 2.69. There are two reasons I decided to not change
> it.
>
> 1) As you may have noticed, there is some code in configure.in that
> seems to detect cross compilation using "nonstandard" or enhanced
> checks -- the code that sets the |cross_compiling| and |CROSS_COMPILE|
> variables. I don't understand that code, so I avoided changing it.
>
> 2) Mozilla's top-level configure.in script follows the same
> convention. Although NSPR is a stand-alone library, it is often
> associated with Mozilla, so I thought it would be good to be
> consistent.  (Mozilla's configure.in can invoke a sub-configure that
> follows a different convention, so NSPR doesn't need to be
> consistent.)
>
> I am not familiar with cross compilation. The best people to talk to
> about this issue would be Mozilla's build system experts, such as Mike
> Hommey and Ted Mielczarek. I don't know if they read this newsgroup
> regularly. I suggest you file a bug report and attach your patch to
> it: https://bugzilla.mozilla.org/enter_bug.cgi?product=NSPR
>
> Thanks,
> Wan-Teh