diff options
Diffstat (limited to 'compiler/GHC/Tc/Module.hs')
| -rw-r--r-- | compiler/GHC/Tc/Module.hs | 19 |
1 files changed, 13 insertions, 6 deletions
diff --git a/compiler/GHC/Tc/Module.hs b/compiler/GHC/Tc/Module.hs index a332d61fb1..9ab53792a8 100644 --- a/compiler/GHC/Tc/Module.hs +++ b/compiler/GHC/Tc/Module.hs @@ -2668,8 +2668,15 @@ tcRnType :: HscEnv tcRnType hsc_env flexi normalise rdr_type = runTcInteractive hsc_env $ setXOptM LangExt.PolyKinds $ -- See Note [Kind-generalise in tcRnType] - do { (HsWC { hswc_ext = wcs, hswc_body = rn_type }, _fvs) - <- rnHsWcType GHCiCtx (mkHsWildCardBndrs rdr_type) + do { (HsWC { hswc_ext = wcs, hswc_body = rn_sig_type@(L _ (HsSig{sig_bndrs = outer_bndrs, sig_body = body })) }, _fvs) + -- we are using 'rnHsSigWcType' to bind the unbound type variables + -- and in combination with 'tcOuterTKBndrs' we are able to + -- implicitly quantify them as if the user wrote 'forall' by + -- hand (see #19217). This allows kind check to work in presence + -- of free type variables : + -- ghci> :k [a] + -- [a] :: * + <- rnHsSigWcType GHCiCtx (mkHsWildCardBndrs $ noLocA (mkHsImplicitSigType rdr_type)) -- The type can have wild cards, but no implicit -- generalisation; e.g. :kind (T _) ; failIfErrsM @@ -2679,14 +2686,14 @@ tcRnType hsc_env flexi normalise rdr_type -- Now kind-check the type -- It can have any rank or kind -- First bring into scope any wildcards - ; traceTc "tcRnType" (vcat [ppr wcs, ppr rn_type]) - ; ((ty, kind), wanted) + ; traceTc "tcRnType" (vcat [ppr wcs, ppr rn_sig_type]) + ; si <- mkSkolemInfo $ SigTypeSkol (GhciCtxt True) + ; ((_, (ty, kind)), wanted) <- captureTopConstraints $ pushTcLevelM_ $ bindNamedWildCardBinders wcs $ \ wcs' -> do { mapM_ emitNamedTypeHole wcs' - ; tcInferLHsTypeUnsaturated rn_type } - + ; tcOuterTKBndrs si outer_bndrs $ tcInferLHsTypeUnsaturated body } -- Since all the wanteds are equalities, the returned bindings will be empty ; empty_binds <- simplifyTop wanted ; massertPpr (isEmptyBag empty_binds) (ppr empty_binds) |