Synchronize ClsInst.doTyConApp with TcTypeable validity checks (#15862)

[ghc.git] / compiler / typecheck / TcBinds.hs

diff --git a/compiler/typecheck/TcBinds.hs b/compiler/typecheck/TcBinds.hs
index b4803fc..c8c1bc0 100644 (file)
--- a/compiler/typecheck/TcBinds.hs
+++ b/compiler/typecheck/TcBinds.hs
@@ -392,14 +392,13 @@ tcValBinds :: TopLevelFlag
            -> TcM ([(RecFlag, LHsBinds GhcTcId)], thing)
 
 tcValBinds top_lvl binds sigs thing_inside
-  = do  { let patsyns = getPatSynBinds binds
-
-            -- Typecheck the signature
+  = do  {   -- Typecheck the signatures
+            -- It's easier to do so now, once for all the SCCs together
+            -- because a single signature  f,g :: <type>
+            -- might relate to more than one SCC
         ; (poly_ids, sig_fn) <- tcAddPatSynPlaceholders patsyns $
                                 tcTySigs sigs
 
-        ; let prag_fn = mkPragEnv sigs (foldr (unionBags . snd) emptyBag binds)
-
                 -- Extend the envt right away with all the Ids
                 -- declared with complete type signatures
                 -- Do not extend the TcBinderStack; instead
@@ -413,6 +412,9 @@ tcValBinds top_lvl binds sigs thing_inside
                    ; let extra_binds = [ (NonRecursive, builder) | builder <- patsyn_builders ]
                    ; return (extra_binds, thing) }
             ; return (binds' ++ extra_binds', thing) }}
+  where
+    patsyns = getPatSynBinds binds
+    prag_fn = mkPragEnv sigs (foldr (unionBags . snd) emptyBag binds)
 
 ------------------------
 tcBindGroups :: TopLevelFlag -> TcSigFun -> TcPragEnv
@@ -1587,7 +1589,7 @@ beta is untouchable.)
 
 Example for (E2), we generate
      q :: beta:1, with constraint (forall:3 a. Integral a => Int ~ beta)
-The beta is untoucable, but floats out of the constraint and can
+The beta is untouchable, but floats out of the constraint and can
 be solved absolutely fine.