Fix some warnings when bootstrapping with GHC 9.0

This fixes two classes of warnings that appear when bootstrapping with GHC 9.0:

* `ghc-boot.cabal` was using `cabal-version: >=1.22`, which `cabal-install-3.4`
  now warns about, instead recommending the use of `cabal-version: 1.22`.
* Several pattern matches were producing `Pattern match(es) are non-exhaustive`
  because of incorrect CPP. The pattern-match coverage checker _did_ become
  smarter in GHC 9.1, however, so I ended up needing to keep the CPP, adjusting
  them to use `#if __GLASGOW_HASKELL__ < 901` instead.

6 files changed, 6 insertions, 6 deletions

diff --git a/compiler/GHC/Cmm/DebugBlock.hs b/compiler/GHC/Cmm/DebugBlock.hs
index 3131b83d5a..0de3efe044 100644
--- a/compiler/GHC/Cmm/DebugBlock.hs
+++ b/compiler/GHC/Cmm/DebugBlock.hs
@@ -118,7 +118,7 @@ cmmDebugGen modLoc decls = map (blocksForScope Nothing) topScopes
               -- recover by copying ticks below.
               scp' | SubScope _ scp' <- scp      = scp'
                    | CombinedScope scp' _ <- scp = scp'
-#if __GLASGOW_HASKELL__ <= 810
+#if __GLASGOW_HASKELL__ < 901
                    | otherwise                   = panic "findP impossible"
 #endif
 
diff --git a/compiler/GHC/Core/Coercion/Opt.hs b/compiler/GHC/Core/Coercion/Opt.hs
index 4353676af6..4783ac6fe1 100644
--- a/compiler/GHC/Core/Coercion/Opt.hs
+++ b/compiler/GHC/Core/Coercion/Opt.hs
@@ -570,7 +570,7 @@ opt_univ env sym prov role oty1 oty2
 
   where
     prov' = case prov of
-#if __GLASGOW_HASKELL__ <= 810
+#if __GLASGOW_HASKELL__ < 901
 -- This alt is redundant with the first match of the FunDef
       PhantomProv kco    -> PhantomProv $ opt_co4_wrap env sym False Nominal kco
 #endif
diff --git a/compiler/GHC/Hs/Expr.hs b/compiler/GHC/Hs/Expr.hs
index 42ae115dab..e1f6e3fd3b 100644
--- a/compiler/GHC/Hs/Expr.hs
+++ b/compiler/GHC/Hs/Expr.hs
@@ -580,7 +580,7 @@ ppr_infix_expr (HsConLikeOut _ c)   = Just (pprInfixOcc (conLikeName c))
 ppr_infix_expr (HsRecFld _ f)       = Just (pprInfixOcc f)
 ppr_infix_expr (HsUnboundVar _ occ) = Just (pprInfixOcc occ)
 ppr_infix_expr (XExpr x)            = case (ghcPass @p, x) of
-#if __GLASGOW_HASKELL__ <= 810
+#if __GLASGOW_HASKELL__ < 901
   (GhcPs, _)                              -> Nothing
 #endif
   (GhcRn, HsExpanded a _)                 -> ppr_infix_expr a
diff --git a/compiler/GHC/Hs/Pat.hs b/compiler/GHC/Hs/Pat.hs
index 2a81beaeb9..406f9d72a5 100644
--- a/compiler/GHC/Hs/Pat.hs
+++ b/compiler/GHC/Hs/Pat.hs
@@ -572,7 +572,7 @@ patNeedsParens p = go
     go (SigPat {})       = p >= sigPrec
     go (ViewPat {})      = True
     go (XPat ext)        = case ghcPass @p of
-#if __GLASGOW_HASKELL__ <= 810
+#if __GLASGOW_HASKELL__ < 901
       GhcPs -> noExtCon ext
       GhcRn -> noExtCon ext
 #endif
diff --git a/compiler/GHC/Tc/Errors/Hole.hs b/compiler/GHC/Tc/Errors/Hole.hs
index 6514968b39..109a4416bc 100644
--- a/compiler/GHC/Tc/Errors/Hole.hs
+++ b/compiler/GHC/Tc/Errors/Hole.hs
@@ -785,7 +785,7 @@ tcFilterHoleFits limit typed_hole ht@(hole_ty, _) candidates =
                                            Just (dataConWrapId con, dataConNonlinearType con)
                                        _ -> Nothing }
             where name = case hfc of
-#if __GLASGOW_HASKELL__ <= 810
+#if __GLASGOW_HASKELL__ < 901
                            IdHFCand id -> idName id
 #endif
                            GreHFCand gre -> greMangledName gre
diff --git a/libraries/ghc-boot/ghc-boot.cabal.in b/libraries/ghc-boot/ghc-boot.cabal.in
index 2dec48f034..eb6ec3bd76 100644
--- a/libraries/ghc-boot/ghc-boot.cabal.in
+++ b/libraries/ghc-boot/ghc-boot.cabal.in
@@ -22,7 +22,7 @@ description:    This library is shared between GHC, ghc-pkg, and other boot
                 The package database format and this library are constructed in
                 such a way that while ghc-pkg depends on Cabal, the GHC library
                 and program do not have to depend on Cabal.
-cabal-version:  >=1.22
+cabal-version:  1.22
 build-type:     Simple
 extra-source-files: changelog.md