help validating a modified compiler?

Richard Eisenberg lists at
Mon Oct 11 20:05:32 UTC 2021

Speaking for myself: I have not validated locally for quite a while. I just rely on CI. You can mark an MR as a "Draft" to avoid triggering a review.

Instead of validating locally, I tend to just run the testsuite on the built GHC. This can be done with hadrian/build test -j<however many processors you have>. (You might want --flavour=<xyz> and --freeze1 --freeze2 there, too, to prevent recompilation.) Then I leave it to CI to do the full job.


> On Oct 11, 2021, at 3:23 PM, Norman Ramsey <nr at> wrote:
> I've made a minor change to GHC, and before submitting a PR, I'd like to
> validate the change.  But I don't really know how to interpret the output
> of the `validate` script.  Mine runs for about 40 minutes and then ends
> in an error:
>  # We are installing wrappers to programs by searching corresponding
>  # wrappers. If wrapper is not found, we are attaching the common wrapper
>  # to it. This implementation is a bit hacky and depends on consistency
>  # of program names. For hadrian build this will work as programs have a
>  # consistent naming procedure.
>  if [ -L wrappers/ghc ]; then echo "ghc is a symlink"; fi
>  ghc is a symlink
>  cp: target 'dir/bin/ghc' is not a directory
>  make: *** [Makefile:197: install_wrappers] Error 1
>  ________________________________________________________
>  Executed in   39.60 mins    fish           external
>     usr time  146.65 mins    0.00 millis  146.65 mins
>     sys time    9.55 mins    1.60 millis    9.55 mins
> I'm in the process of trying `validate` on a fresh checkout, but at 40
> minutes per shot, I feel like I might be on the wrong track.  Should I
> just create a merge request and rely on CI for the validation?
> Or do something else?
> Norman
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