[Git][ghc/ghc][wip/T25647] Add comment to clarify implementation details for wildcards in family instances

[Patrick (@soulomoon)]

Patrick pushed to branch wip/T25647 at Glasgow Haskell Compiler / GHC


Commits:
f8b64564 by Patrick at 2025-03-05T22:23:56+08:00
Add comment to clarify implementation details for wildcards in family instances

- - - - -


1 changed file:

- compiler/GHC/Tc/Gen/HsType.hs


Changes:

=====================================
compiler/GHC/Tc/Gen/HsType.hs
=====================================
@@ -2261,12 +2261,13 @@ tcAnonWildCardOcc is_extra (TcTyMode { mode_holes = Just (hole_lvl, hole_mode) }
                HM_FamPat _  -> fsLit "_"
                HM_VTA       -> fsLit "w"
                HM_TyAppPat  -> fsLit "_"
+
+     -- see Note [Implementation tweak for wildCards in family instances]
      mk_wc_details = case hole_mode of
                       HM_FamPat FreeArg -> newTyVarMetaVarDetailsAtLevel
                       HM_FamPat ClassArg -> newTauTvDetailsAtLevel
                       HM_FamPat SigArg -> newTauTvDetailsAtLevel
                       _ -> newTauTvDetailsAtLevel
-                      -- see Note [Implementation tweak for wildCards in family instances]
      emit_holes = case hole_mode of
                      HM_Sig       -> True
                      HM_FamPat _  -> False



View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/f8b64564d411b8e688884257e7ddf100b0ed6aa6

-- 
View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/f8b64564d411b8e688884257e7ddf100b0ed6aa6
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