GHC-6.12.1: broken configure

Simon Marlow marlowsd at
Wed Dec 30 06:57:26 EST 2009

On 24/12/09 14:01, Ian Lynagh wrote:
> On Wed, Dec 23, 2009 at 09:49:40PM +0000, Simon Marlow wrote:
>> On 22/12/09 12:59, Jens Petersen wrote:
>>> 2009/12/19 Kirill A. Shutemov<kirill at>:
>>>> I want to build ghc for i586-alt-linux-gnu.
>>> Why? :)
>>>> Why do not use config.guess to guess correct host/target/build
>>>> instead of reinvent wheel?
>>> While I sympathize (I gave up long ago trying to use  host/target/build
>>> with ghc - we use them by default in Fedora) - I guess the short answer
>>> is something like cross-compiling is not supported or the effort
>>> to support host/target/build is more than the win?  But those
>>> are just my assumptions - I leave a real answer to a ghc buildsystem
>>> expert.
>>> If you really want a fix searching trac and opening a ticket would be
>>> more effective probably.
>> I personally think we should revert to using the standard config.guess
>> and normalising the result as we used to.
> I don't see the advantage. Before we had 484 lines of case expression in
>, which now and again needed tweaking to keep up with
> changes in configure.
> Now we don't need to be told the platform that we are building for, as
> we just ask the bootstrapping compiler what platform it builds for, and
> we only support building for that platform anyway. If you specify a
> different platform then the build will break. I don't know if the
> original poster means that he wants i586 as opposed to e.g. i386 (to
> make use of newer instructions or to optimise differently), but if so we
> don't do anything different for different subarches.
> As far as I can see, the only reason we would need to support all the
> platform values that configure supports is if/when we are going to
> support cross-compilation.

Yes, that's the main reason. Eventually we will want to do 
cross-compilation, so I think it makes sense to retain the possibility. 
There's also the reason that people are building GHC in environments 
that expect to be able to pass GNU-standard --host options to configure.

The normalisation doesn't necessarily need to be as long or complicated 
as it was before: we could normalise the machine and os separately, and 
ignore the vendor.  We should check that the bootstrapping GHC agrees 
with the build platform.


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