building ghc once or twice?

Ben Gamari ben at
Wed May 2 14:45:55 UTC 2018

Jens Petersen <juhpetersen at> writes:

> I have been packaging ghc for a long time...
> In older times I think it was recommended to first do a (quick) build
> of a new version of ghc (with the previous version) and then to do a
> (perf) rebuild of the new version against itself.
> In fact I am still building ghc this way for Fedora: though it seems
> like this is overhead nowadays...?
> (I think one major reason was to get stable ABI hashes for the core
> library packages.)
> These days should I just do a single default or perf build of a new
> ghc version against a previous stable release, or does it still make
> sense to continue to build in two steps like I have been doing?
> Any pros or cons?
Indeed; GHC's build system already performs a two-stage bootstrapping so
it shouldn't be necessary to do multiple builds yourself.


- Ben

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