Help with build ordering issue

Sylvain Henry sylvain at
Mon Feb 26 19:11:07 UTC 2018

On 26/02/2018 19:19, Ben Gamari wrote:
> Sylvain Henry <sylvain at> writes:
>> On 25/02/2018 21:30, Ben Gamari wrote:
>>> Hmm, I'm afraid that's not particularly illuminating.
>>> It would be helpful to see the output from -ddump-if-trace as this will
>>> tell you why GHC is trying to load this interface file.
>> Thanks, it has been helpful. The relevant trace is:
>> Need decl for mkNatural
>> Considering whether to load GHC.Natural {- SYSTEM -}
>> Reading interface for base-;
>>       reason: Need decl for mkNatural
>> readIFace libraries/base/dist-install/build/GHC/Natural.hi
>> Now I still don't know why GHC is trying to load the interface of the
>> module it is compiling.
> Keep in mind that GHC may call upon mkNatural while typechecking even
> without an import as it is known-key. The output of -ddump-tc-trace
> might also help identify whether this is the case.

It must be something like this because I get the same error even when I 
reduce GHC.Natural module to:

{-# LANGUAGE NoImplicitPrelude #-}
module GHC.Natural where

> I would help if there were some way I could reproduce this.
The failing patch is here:

Let's continue the discussion there to avoid spamming this list ;)


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