with ghc-9.10: Couldn't match expected type ‘ArgPat’ with actual type ‘Pat’

[jwaldmann]

fast/Data/Reflection.hs:419:15: error: [GHC-83865]
    • Couldn't match expected type ‘ArgPat’ with actual type ‘Pat’
    • In the expression: SigP WildP na
      In the first argument of ‘LamE’, namely ‘[SigP WildP na]’
      In the first argument of ‘AppE’, namely ‘LamE [SigP WildP na] body’
    |
419 |         LamE [SigP WildP na] body `AppE` a
    |               ^^^^^^^^^^^^^

see https://gitlab.haskell.org/ghc/ghc/-/blob/master/libraries/template-haskell/changelog.md?ref_type=heads#anchor-22200 ("Added new data type ArgPat with two constructors")

[RyanGlScott]

I'm aware of this, but I'd like to hold off until the discussion in https://gitlab.haskell.org/ghc/ghc/-/issues/24557 reaches a consensus.

[jwaldmann]

yes, fine. I was just trying to "9.10" my code as far as possible to see what breaks (in my code) or what is broken (in ghc alpha - seems I found two bugs recently)

[erikd]

#metoo .

[andreasabel]

This issue might resolve itself with the next alpha of GHC 9.10.

[erikd]

@andreasabel You mean ghc-9.10.0.20240328 (which is 9.10.0-alpha2)? I can confirm that it does not.

[andreasabel]

@erikd : No, I meant alpha3 or higher.

• https://gitlab.haskell.org/ghc/ghc/-/commit/36a75b80ebe592f582f3f349e8c73b8293d49ed1

[RyanGlScott]

GHC 9.10.1-alpha3 is out, and I've confirmed that reflection builds without issue using that alpha. As such, I'll close this. Please re-open if there is something else I've missed.