Support signatures at the kind level in Template Haskell

`repNonArrowKind` was missing a case for `HsKindSig`, which this
commit adds. Fixes #13781.

Test Plan: make test TEST=T13781

Reviewers: goldfire, austin, bgamari

Reviewed By: goldfire

Subscribers: rwbarton, thomie

GHC Trac Issues: #13781

Differential Revision: https://phabricator.haskell.org/D3627

2 files changed, 32 insertions, 13 deletions

diff --git a/compiler/deSugar/DsMeta.hs b/compiler/deSugar/DsMeta.hs
index f7f2fd597e..d23ac3894a 100644
--- a/compiler/deSugar/DsMeta.hs
+++ b/compiler/deSugar/DsMeta.hs
@@ -1069,6 +1069,12 @@ repTyLit (HsStrTy _ s) = do { s' <- mkStringExprFS s
 
 -- represent a kind
 --
+-- It would be great to scrap this function in favor of repLTy, since Types
+-- and Kinds are the same things. We have not done so yet for engineering
+-- reasons, as repLTy returns a monadic TypeQ, whereas repLKind returns a pure
+-- Kind, so in order to replace repLKind with repLTy, we'd need to go through
+-- and purify repLTy and every monadic function it calls. This is the subject
+-- GHC Trac #11785.
 repLKind :: LHsKind GhcRn -> DsM (Core TH.Kind)
 repLKind ki
   = do { let (kis, ki') = splitHsFunType ki
@@ -1109,6 +1115,10 @@ repNonArrowKind (HsTupleTy _ ks)    = do  { ks' <- mapM repLKind ks
                                           ; kcon <- repKTuple (length ks)
                                           ; repKApps kcon ks'
                                           }
+repNonArrowKind (HsKindSig k sort)  = do  { k'    <- repLKind k
+                                          ; sort' <- repLKind sort
+                                          ; repKSig k' sort'
+                                          }
 repNonArrowKind k                   = notHandled "Exotic form of kind" (ppr k)
 
 repRole :: Located (Maybe Role) -> DsM (Core TH.Role)
@@ -2351,6 +2361,9 @@ repKStar = rep2 starKName []
 repKConstraint :: DsM (Core TH.Kind)
 repKConstraint = rep2 constraintKName []
 
+repKSig :: Core TH.Kind -> Core TH.Kind -> DsM (Core TH.Kind)
+repKSig (MkC k) (MkC sort) = rep2 sigTDataConName [k, sort]
+
 ----------------------------------------------------------
 --       Type family result signature
 
diff --git a/compiler/prelude/THNames.hs b/compiler/prelude/THNames.hs
index 1b9e624c67..9502e9e654 100644
--- a/compiler/prelude/THNames.hs
+++ b/compiler/prelude/THNames.hs
@@ -94,7 +94,7 @@ templateHaskellNames = [
     -- Type
     forallTName, varTName, conTName, appTName, equalityTName,
     tupleTName, unboxedTupleTName, unboxedSumTName,
-    arrowTName, listTName, sigTName, litTName,
+    arrowTName, listTName, sigTName, sigTDataConName, litTName,
     promotedTName, promotedTupleTName, promotedNilTName, promotedConsTName,
     wildCardTName,
     -- TyLit
@@ -428,9 +428,10 @@ recordPatSynName = libFun (fsLit "recordPatSyn") recordPatSynIdKey
 
 -- data Type = ...
 forallTName, varTName, conTName, tupleTName, unboxedTupleTName,
-    unboxedSumTName, arrowTName, listTName, appTName, sigTName, equalityTName,
-    litTName, promotedTName, promotedTupleTName, promotedNilTName,
-    promotedConsTName, wildCardTName :: Name
+    unboxedSumTName, arrowTName, listTName, appTName, sigTName,
+    sigTDataConName, equalityTName, litTName, promotedTName,
+    promotedTupleTName, promotedNilTName, promotedConsTName,
+    wildCardTName :: Name
 forallTName         = libFun (fsLit "forallT")        forallTIdKey
 varTName            = libFun (fsLit "varT")           varTIdKey
 conTName            = libFun (fsLit "conT")           conTIdKey
@@ -441,6 +442,9 @@ arrowTName          = libFun (fsLit "arrowT")         arrowTIdKey
 listTName           = libFun (fsLit "listT")          listTIdKey
 appTName            = libFun (fsLit "appT")           appTIdKey
 sigTName            = libFun (fsLit "sigT")           sigTIdKey
+-- Yes, we need names for both the monadic sigT as well as the pure SigT. Why?
+-- Refer to the documentation for repLKind in DsMeta.
+sigTDataConName     = thCon  (fsLit "SigT")           sigTDataConKey
 equalityTName       = libFun (fsLit "equalityT")      equalityTIdKey
 litTName            = libFun (fsLit "litT")           litTIdKey
 promotedTName       = libFun (fsLit "promotedT")      promotedTIdKey
@@ -947,8 +951,9 @@ recordPatSynIdKey = mkPreludeMiscIdUnique 372
 -- data Type = ...
 forallTIdKey, varTIdKey, conTIdKey, tupleTIdKey, unboxedTupleTIdKey,
     unboxedSumTIdKey, arrowTIdKey, listTIdKey, appTIdKey, sigTIdKey,
-    equalityTIdKey, litTIdKey, promotedTIdKey, promotedTupleTIdKey,
-    promotedNilTIdKey, promotedConsTIdKey, wildCardTIdKey :: Unique
+    sigTDataConKey, equalityTIdKey, litTIdKey, promotedTIdKey,
+    promotedTupleTIdKey, promotedNilTIdKey, promotedConsTIdKey,
+    wildCardTIdKey :: Unique
 forallTIdKey        = mkPreludeMiscIdUnique 381
 varTIdKey           = mkPreludeMiscIdUnique 382
 conTIdKey           = mkPreludeMiscIdUnique 383
@@ -959,13 +964,14 @@ arrowTIdKey         = mkPreludeMiscIdUnique 387
 listTIdKey          = mkPreludeMiscIdUnique 388
 appTIdKey           = mkPreludeMiscIdUnique 389
 sigTIdKey           = mkPreludeMiscIdUnique 390
-equalityTIdKey      = mkPreludeMiscIdUnique 391
-litTIdKey           = mkPreludeMiscIdUnique 392
-promotedTIdKey      = mkPreludeMiscIdUnique 393
-promotedTupleTIdKey = mkPreludeMiscIdUnique 394
-promotedNilTIdKey   = mkPreludeMiscIdUnique 395
-promotedConsTIdKey  = mkPreludeMiscIdUnique 396
-wildCardTIdKey      = mkPreludeMiscIdUnique 397
+sigTDataConKey      = mkPreludeMiscIdUnique 391
+equalityTIdKey      = mkPreludeMiscIdUnique 392
+litTIdKey           = mkPreludeMiscIdUnique 393
+promotedTIdKey      = mkPreludeMiscIdUnique 394
+promotedTupleTIdKey = mkPreludeMiscIdUnique 395
+promotedNilTIdKey   = mkPreludeMiscIdUnique 396
+promotedConsTIdKey  = mkPreludeMiscIdUnique 397
+wildCardTIdKey      = mkPreludeMiscIdUnique 398
 
 -- data TyLit = ...
 numTyLitIdKey, strTyLitIdKey :: Unique