Add a HasTypeProxy constraint to getVerificationKey

This constraint is needed in `cardano-cli`.

Annoyingly, `ghc-8.10` considers this constraint redundant while
`ghc-9.2` and later complains if its absent.

cardano-api/gen/Test/Gen/Cardano/Api/Typed.hs

@@ -1,3 +1,4 @@
+{-# LANGUAGE CPP #-}
 {-# LANGUAGE GADTs #-}
 {-# LANGUAGE NamedFieldPuns #-}
 {-# LANGUAGE OverloadedStrings #-}
@@ -746,10 +747,26 @@ genWitnesses era =
                           (genShelleyKeyWitness era)
       return $ bsWits ++ keyWits
 
-genVerificationKey :: Key keyrole => AsType keyrole -> Gen (VerificationKey keyrole)
+genVerificationKey ::
+#if __GLASGOW_HASKELL__ >= 902
+-- GHC 8.10 considers the HasTypeProxy constraint redundant but ghc-9.6 complains if its not
+-- present.
+    (Key keyrole, HasTypeProxy keyrole) =>
+#else
+    Key keyrole =>
+#endif
+    AsType keyrole -> Gen (VerificationKey keyrole)
 genVerificationKey roletoken = getVerificationKey <$> genSigningKey roletoken
 
-genVerificationKeyHash :: Key keyrole => AsType keyrole -> Gen (Hash keyrole)
+genVerificationKeyHash ::
+#if __GLASGOW_HASKELL__ >= 902
+-- GHC 8.10 considers the HasTypeProxy constraint redundant but ghc-9.6 complains if its not
+-- present.
+    (Key keyrole, HasTypeProxy keyrole) =>
+#else
+    Key keyrole =>
+#endif
+    AsType keyrole -> Gen (Hash keyrole)
 genVerificationKeyHash roletoken =
   verificationKeyHash <$> genVerificationKey roletoken
 

cardano-api/internal/Cardano/Api/Keys/Class.hs

@@ -1,3 +1,4 @@
+{-# LANGUAGE CPP #-}
 {-# LANGUAGE FlexibleContexts #-}
 {-# LANGUAGE MultiParamTypeClasses #-}
 {-# LANGUAGE TypeFamilies #-}
@@ -44,7 +45,14 @@ class (Eq (VerificationKey keyrole),
     data SigningKey keyrole :: Type
 
     -- | Get the corresponding verification key from a signing key.
-    getVerificationKey :: SigningKey keyrole -> VerificationKey keyrole
+    getVerificationKey ::
+#if __GLASGOW_HASKELL__ >= 902
+-- GHC 8.10 considers this constraint redundant but ghc-9.6 complains if its not present.
+-- More annoyingly, absence of this constraint does not manifest in this repo, but in
+-- `cardano-cli` :facepalm:.
+        HasTypeProxy keyrole =>
+#endif
+        SigningKey keyrole -> VerificationKey keyrole
 
     -- | Generate a 'SigningKey' deterministically, given a 'Crypto.Seed'. The
     -- required size of the seed is given by 'deterministicSigningKeySeedSize'.

cardano-api/test/cardano-api-test/Test/Cardano/Api/Typed/Envelope.hs

@@ -1,3 +1,4 @@
+{-# LANGUAGE CPP #-}
 {-# LANGUAGE FlexibleContexts #-}
 
 module Test.Cardano.Api.Typed.Envelope
@@ -89,8 +90,15 @@ prop_roundtrip_VrfSigningKey_envelope =
 
 -- -----------------------------------------------------------------------------
 
-roundtrip_VerificationKey_envelope :: Key keyrole
-                                   => AsType keyrole -> Property
+roundtrip_VerificationKey_envelope ::
+#if __GLASGOW_HASKELL__ >= 902
+-- GHC 8.10 considers the HasTypeProxy constraint redundant but ghc-9.2 and above complains if its
+-- not present.
+    (Key keyrole, HasTypeProxy keyrole) =>
+#else
+    Key keyrole =>
+#endif
+    AsType keyrole -> Property
 roundtrip_VerificationKey_envelope roletoken =
   H.property $ do
     vkey <- H.forAll (genVerificationKey roletoken)

cardano-api/test/cardano-api-test/Test/Cardano/Api/Typed/RawBytes.hs

@@ -85,10 +85,10 @@ roundtrip_raw_bytes asType g =
     H.tripping v serialiseToRawBytes (deserialiseFromRawBytes asType)
 
 roundtrip_verification_key_hash_raw
-#if __GLASGOW_HASKELL__ < 906
+#if __GLASGOW_HASKELL__ < 902
   :: (Key keyrole, Eq (Hash keyrole), Show (Hash keyrole))
 #else
-  -- GHC 9.6 needs an extra constraint.
+  -- GHC 9.2 and above needs an extra constraint.
   :: (Key keyrole, Eq (Hash keyrole), Show (Hash keyrole), HasTypeProxy keyrole)
 #endif
   => AsType keyrole -> Property