Require GHC 8.10 as the minimum compiler for bootstrapping

Now that GHC 9.0.1 is released, it is time to drop support for bootstrapping
with GHC 8.8, as we only support building with the previous two major GHC
releases. As an added bonus, this allows us to remove several bits of CPP that
are either always true or no longer reachable.

19 files changed, 32 insertions, 95 deletions

diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index cb4c6d4bcc..d91e3b8f76 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -485,8 +485,8 @@ validate-x86_64-darwin:
   tags:
     - x86_64-darwin
   variables:
-    GHC_VERSION: 8.8.4
-    CABAL_INSTALL_VERSION: 3.0.0.0
+    GHC_VERSION: 8.10.4
+    CABAL_INSTALL_VERSION: 3.2.0.0
     BIN_DIST_PREP_TAR_COMP: "ghc-x86_64-apple-darwin.tar.xz"
     MACOSX_DEPLOYMENT_TARGET: "10.7"
     # Only Sierra and onwards supports clock_gettime. See #12858
@@ -518,7 +518,7 @@ validate-x86_64-darwin:
   tags:
     - x86_64-darwin
   variables:
-    GHC_VERSION: 8.8.4
+    GHC_VERSION: 8.10.4
     MACOSX_DEPLOYMENT_TARGET: "10.7"
     ac_cv_func_clock_gettime: "no"
     LANG: "en_US.UTF-8"
@@ -979,8 +979,8 @@ release-x86_64-linux-fedora27-dwarf:
     #FORCE_SYMLINKS: 1
     LANG: "en_US.UTF-8"
     SPHINXBUILD: "/mingw64/bin/sphinx-build.exe"
-    CABAL_INSTALL_VERSION: "3.0.0.0"
-    GHC_VERSION: "8.8.4"
+    CABAL_INSTALL_VERSION: "3.2.0.0"
+    GHC_VERSION: "8.10.4"
   cache:
     paths:
       - cabal-cache
diff --git a/compiler/GHC/CmmToAsm/X86/CodeGen.hs b/compiler/GHC/CmmToAsm/X86/CodeGen.hs
index 36b24e8be2..60d19f43c1 100644
--- a/compiler/GHC/CmmToAsm/X86/CodeGen.hs
+++ b/compiler/GHC/CmmToAsm/X86/CodeGen.hs
@@ -4,13 +4,6 @@
 {-# LANGUAGE NondecreasingIndentation #-}
 {-# LANGUAGE TupleSections #-}
 
-#if __GLASGOW_HASKELL__ <= 808
--- GHC 8.10 deprecates this flag, but GHC 8.8 needs it
--- The default iteration limit is a bit too low for the definitions
--- in this module.
-{-# OPTIONS_GHC -fmax-pmcheck-iterations=10000000 #-}
-#endif
-
 {-# OPTIONS_GHC -Wno-incomplete-uni-patterns #-}
 
 -----------------------------------------------------------------------------
diff --git a/compiler/GHC/Core/Opt/ConstantFold.hs b/compiler/GHC/Core/Opt/ConstantFold.hs
index 02a3983e92..c463bda314 100644
--- a/compiler/GHC/Core/Opt/ConstantFold.hs
+++ b/compiler/GHC/Core/Opt/ConstantFold.hs
@@ -23,13 +23,6 @@ ToDo:
 
 {-# OPTIONS_GHC -optc-DNON_POSIX_SOURCE -Wno-incomplete-uni-patterns #-}
 
-#if __GLASGOW_HASKELL__ <= 808
--- GHC 8.10 deprecates this flag, but GHC 8.8 needs it
--- The default iteration limit is a bit too low for the definitions
--- in this module.
-{-# OPTIONS_GHC -fmax-pmcheck-iterations=20000000 #-}
-#endif
-
 -- | Constant Folder
 module GHC.Core.Opt.ConstantFold
    ( primOpRules
diff --git a/compiler/GHC/Iface/Type.hs b/compiler/GHC/Iface/Type.hs
index eaba819a74..ae0d592959 100644
--- a/compiler/GHC/Iface/Type.hs
+++ b/compiler/GHC/Iface/Type.hs
@@ -14,12 +14,6 @@ This module defines interface types and binders
 {-# LANGUAGE TupleSections #-}
 {-# LANGUAGE LambdaCase #-}
 
-#if !MIN_VERSION_GLASGOW_HASKELL(8,10,0,0)
-{-# OPTIONS_GHC -Wno-overlapping-patterns -Wno-incomplete-patterns #-}
-  -- N.B. This can be dropped once GHC 8.8 can be dropped as a
-  -- bootstrap compiler.
-#endif
-
 module GHC.Iface.Type (
         IfExtName, IfLclName,
 
diff --git a/compiler/GHC/StgToCmm/Prim.hs b/compiler/GHC/StgToCmm/Prim.hs
index a0acdf897a..b10462a10b 100644
--- a/compiler/GHC/StgToCmm/Prim.hs
+++ b/compiler/GHC/StgToCmm/Prim.hs
@@ -1,12 +1,6 @@
 {-# LANGUAGE CPP #-}
 {-# LANGUAGE LambdaCase #-}
 
-#if __GLASGOW_HASKELL__ <= 808
--- GHC 8.10 deprecates this flag, but GHC 8.8 needs it
--- emitPrimOp is quite large
-{-# OPTIONS_GHC -fmax-pmcheck-iterations=4000000 #-}
-#endif
-
 {-# OPTIONS_GHC -Wno-incomplete-uni-patterns #-}
 
 ----------------------------------------------------------------------------
diff --git a/compiler/GHC/SysTools/Process.hs b/compiler/GHC/SysTools/Process.hs
index 1159506d18..d98710febd 100644
--- a/compiler/GHC/SysTools/Process.hs
+++ b/compiler/GHC/SysTools/Process.hs
@@ -40,14 +40,10 @@ import GHC.Utils.TmpFs
 -- @process >= 1.6.9.0@).
 enableProcessJobs :: CreateProcess -> CreateProcess
 #if defined(MIN_VERSION_process)
-#if MIN_VERSION_process(1,6,9)
 enableProcessJobs opts = opts { use_process_jobs = True }
 #else
 enableProcessJobs opts = opts
 #endif
-#else
-enableProcessJobs opts = opts
-#endif
 
 #if !MIN_VERSION_base(4,15,0)
 -- TODO: This can be dropped with GHC 8.16
diff --git a/compiler/GHC/Utils/Binary/Typeable.hs b/compiler/GHC/Utils/Binary/Typeable.hs
index ebee92e211..636733357a 100644
--- a/compiler/GHC/Utils/Binary/Typeable.hs
+++ b/compiler/GHC/Utils/Binary/Typeable.hs
@@ -136,10 +136,8 @@ instance Binary RuntimeRep where
     put_ bh Word8Rep        = putByte bh 13
     put_ bh Int16Rep        = putByte bh 14
     put_ bh Word16Rep       = putByte bh 15
-#if __GLASGOW_HASKELL__ >= 809
     put_ bh Int32Rep        = putByte bh 16
     put_ bh Word32Rep       = putByte bh 17
-#endif
 
     get bh = do
         tag <- getByte bh
@@ -165,10 +163,8 @@ instance Binary RuntimeRep where
           13 -> pure Word8Rep
           14 -> pure Int16Rep
           15 -> pure Word16Rep
-#if __GLASGOW_HASKELL__ >= 809
           16 -> pure Int32Rep
           17 -> pure Word32Rep
-#endif
           _  -> fail "Binary.putRuntimeRep: invalid tag"
 
 instance Binary KindRep where
diff --git a/configure.ac b/configure.ac
index fcf74567d3..2645ee5aa1 100644
--- a/configure.ac
+++ b/configure.ac
@@ -191,8 +191,8 @@ if test "$WithGhc" = ""
 then
     AC_MSG_ERROR([GHC is required.])
 fi
-FP_COMPARE_VERSIONS([$GhcVersion],[-lt],[8.8],
-    [AC_MSG_ERROR([GHC version 8.8 or later is required to compile GHC.])])
+FP_COMPARE_VERSIONS([$GhcVersion],[-lt],[8.10],
+    [AC_MSG_ERROR([GHC version 8.10 or later is required to compile GHC.])])
 
 if test `expr $GhcMinVersion % 2` = "1"
 then
diff --git a/hadrian/hadrian.cabal b/hadrian/hadrian.cabal
index c82ff82428..408cdc4f37 100644
--- a/hadrian/hadrian.cabal
+++ b/hadrian/hadrian.cabal
@@ -134,7 +134,7 @@ executable hadrian
                        , BangPatterns
     other-extensions:    MultiParamTypeClasses
                        , TypeFamilies
-    build-depends:       Cabal                >= 3.0     && < 3.5
+    build-depends:       Cabal                >= 3.2     && < 3.5
                        , QuickCheck           >= 2.6     && < 2.15
                        , base                 >= 4.8     && < 5
                        , bytestring           >= 0.10    && < 0.12
diff --git a/hadrian/src/Hadrian/Haskell/Cabal/Parse.hs b/hadrian/src/Hadrian/Haskell/Cabal/Parse.hs
index 776edb15e7..49352c6823 100644
--- a/hadrian/src/Hadrian/Haskell/Cabal/Parse.hs
+++ b/hadrian/src/Hadrian/Haskell/Cabal/Parse.hs
@@ -38,9 +38,7 @@ import qualified Distribution.Simple.PackageIndex              as C
 import qualified Distribution.Text                             as C
 import qualified Distribution.Types.LocalBuildInfo             as C
 import qualified Distribution.Types.MungedPackageId            as C
-#if MIN_VERSION_Cabal(3,2,0)
 import qualified Distribution.Utils.ShortText                  as C
-#endif
 #if !MIN_VERSION_Cabal(3,4,0)
 import qualified Distribution.Types.CondTree                   as C
 #endif
@@ -76,8 +74,8 @@ parsePackageData pkg = do
         deps    = nubOrd sorted \\ [name]
         depPkgs = catMaybes $ map findPackageByName deps
     return $ PackageData name version
-                         (shortTextToString (C.synopsis pd))
-                         (shortTextToString (C.description pd))
+                         (C.fromShortText (C.synopsis pd))
+                         (C.fromShortText (C.description pd))
                          depPkgs gpd
   where
     -- Collect an overapproximation of dependencies by ignoring conditionals
@@ -87,14 +85,6 @@ parsePackageData pkg = do
       where
         f (C.CondBranch _ t mt) = collectDeps (Just t) ++ collectDeps mt
 
-#if MIN_VERSION_Cabal(3,2,0)
-    shortTextToString :: C.ShortText -> String
-    shortTextToString = C.fromShortText
-#else
-    shortTextToString :: String -> String
-    shortTextToString = id
-#endif
-
 -- | Parse the package identifier from a Cabal file.
 parseCabalPkgId :: FilePath -> IO String
 parseCabalPkgId file = C.display . C.package . C.packageDescription <$> C.readGenericPackageDescription C.silent file
diff --git a/hadrian/stack.yaml b/hadrian/stack.yaml
index 9147e2dc57..20ed0c7ac7 100644
--- a/hadrian/stack.yaml
+++ b/hadrian/stack.yaml
@@ -1,4 +1,4 @@
-resolver: lts-16.14
+resolver: lts-17.5
 
 packages:
 - '.'
@@ -12,7 +12,3 @@ nix:
    - git
    - ncurses
    - perl
-
-extra-deps:
-- alex-3.2.6
-- happy-1.20.0
diff --git a/hadrian/stack.yaml.lock b/hadrian/stack.yaml.lock
new file mode 100644
index 0000000000..1bba64b861
--- /dev/null
+++ b/hadrian/stack.yaml.lock
@@ -0,0 +1,12 @@
+# This file was autogenerated by Stack.
+# You should not edit this file by hand.
+# For more information, please see the documentation at:
+#   https://docs.haskellstack.org/en/stable/lock_files
+
+snapshots:
+- original: lts-17.5
+  completed:
+    sha256: 78e8ebabf11406261abbc95b44f240acf71802630b368888f6d758de7fc3a2f7
+    url: https://raw.githubusercontent.com/commercialhaskell/stackage-snapshots/master/lts/17/5.yaml
+    size: 565266
+packages: []
diff --git a/libraries/base/GHC/Windows.hs b/libraries/base/GHC/Windows.hs
index d8f8bef804..be0c3837a9 100644
--- a/libraries/base/GHC/Windows.hs
+++ b/libraries/base/GHC/Windows.hs
@@ -74,7 +74,7 @@ module GHC.Windows (
         nullHANDLE,
     ) where
 
-import Data.Bits (shiftL, shiftR, (.|.), (.&.))
+import Data.Bits (finiteBitSize, shiftL, shiftR, (.|.), (.&.))
 import Data.Char
 import Data.OldList
 import Data.Maybe
@@ -93,15 +93,6 @@ import System.IO.Error
 
 import qualified Numeric
 
-#if MIN_VERSION_base(4,7,0)
-import Data.Bits (finiteBitSize)
-#else
-import Data.Bits (Bits, bitSize)
-
-finiteBitSize :: (Bits a) => a -> Int
-finiteBitSize = bitSize
-#endif
-
 #include "windows_cconv.h"
 
 type BOOL     = Bool
diff --git a/libraries/ghc-heap/GHC/Exts/Heap.hs b/libraries/ghc-heap/GHC/Exts/Heap.hs
index 1e429ca054..2906cf6926 100644
--- a/libraries/ghc-heap/GHC/Exts/Heap.hs
+++ b/libraries/ghc-heap/GHC/Exts/Heap.hs
@@ -153,14 +153,7 @@ getClosureDataFromHeapObject
     -- ^ Heap representation of the closure.
 getClosureDataFromHeapObject x = do
     case unpackClosure# x of
-#if MIN_VERSION_ghc_prim(0,5,3)
         (# infoTableAddr, heapRep, pointersArray #) -> do
-#else
-        -- This is a hack to cover the bootstrap compiler using the old version
-        -- of 'unpackClosure'. The new 'unpackClosure' return values are not
-        -- merely a reordering, so using the old version would not work.
-        (# infoTableAddr, pointersArray, heapRep #) -> do
-#endif
             let infoTablePtr = Ptr infoTableAddr
                 ptrList = [case indexArray# pointersArray i of
                                 (# ptr #) -> Box ptr
diff --git a/libraries/ghc-heap/GHC/Exts/Heap/Closures.hs b/libraries/ghc-heap/GHC/Exts/Heap/Closures.hs
index 1a6a9371d4..3b51b22ceb 100644
--- a/libraries/ghc-heap/GHC/Exts/Heap/Closures.hs
+++ b/libraries/ghc-heap/GHC/Exts/Heap/Closures.hs
@@ -16,12 +16,7 @@ module GHC.Exts.Heap.Closures (
     , WhyBlocked(..)
     , TsoFlags(..)
     , allClosures
-#if __GLASGOW_HASKELL__ >= 809
-    -- The closureSize# primop is unsupported on earlier GHC releases but we
-    -- build ghc-heap as a boot library so it must be buildable. Drop this once
-    -- we are guaranteed to bootstsrap with GHC >= 8.9.
     , closureSize
-#endif
 
     -- * Boxes
     , Box(..)
@@ -430,11 +425,9 @@ allClosures (WeakClosure {..}) = [cfinalizers, key, value, finalizer, link]
 allClosures (OtherClosure {..}) = hvalues
 allClosures _ = []
 
-#if __GLASGOW_HASKELL__ >= 809
 -- | Get the size of the top-level closure in words.
 -- Includes header and payload. Does not follow pointers.
 --
 -- @since 8.10.1
 closureSize :: Box -> Int
 closureSize (Box x) = I# (closureSize# x)
-#endif
diff --git a/libraries/template-haskell/Language/Haskell/TH/Lib/Internal.hs b/libraries/template-haskell/Language/Haskell/TH/Lib/Internal.hs
index 67017d4926..a41d0a47b3 100644
--- a/libraries/template-haskell/Language/Haskell/TH/Lib/Internal.hs
+++ b/libraries/template-haskell/Language/Haskell/TH/Lib/Internal.hs
@@ -1,4 +1,5 @@
 {-# LANGUAGE PolyKinds #-}
+{-# LANGUAGE StandaloneKindSignatures #-}
 {-# LANGUAGE Trustworthy #-}
 
 -- |
@@ -29,17 +30,12 @@ import Prelude
 -- * Type synonyms
 ----------------------------------------------------------
 
--- Since GHC 8.8 is currently the minimum boot compiler version that we must
--- support, we must use inline kind signatures to make TExpQ and CodeQ
--- levity polymorphic. When we drop support for GHC 8.8, we can instead use
--- standalone kind signatures, which are provided as comments.
-
 -- | Levity-polymorphic since /template-haskell-2.17.0.0/.
--- type TExpQ :: TYPE r -> Kind.Type
-type TExpQ (a :: TYPE r) = Q (TExp a)
+type TExpQ :: TYPE r -> Kind.Type
+type TExpQ a = Q (TExp a)
 
--- type CodeQ :: TYPE r -> Kind.Type
-type CodeQ = Code Q :: (TYPE r -> Kind.Type)
+type CodeQ :: TYPE r -> Kind.Type
+type CodeQ = Code Q
 
 type InfoQ               = Q Info
 type PatQ                = Q Pat
diff --git a/utils/check-api-annotations/check-api-annotations.cabal b/utils/check-api-annotations/check-api-annotations.cabal
index 8bf0fb6922..dbaa25fd48 100644
--- a/utils/check-api-annotations/check-api-annotations.cabal
+++ b/utils/check-api-annotations/check-api-annotations.cabal
@@ -24,6 +24,6 @@ Executable check-api-annotations
 
     Build-Depends: base       >= 4   && < 5,
                    containers,
-                   Cabal      >= 3.0 && < 3.6,
+                   Cabal      >= 3.2 && < 3.6,
                    directory,
                    ghc
diff --git a/utils/check-ppr/check-ppr.cabal b/utils/check-ppr/check-ppr.cabal
index 059a4d364c..c9ff366786 100644
--- a/utils/check-ppr/check-ppr.cabal
+++ b/utils/check-ppr/check-ppr.cabal
@@ -25,7 +25,7 @@ Executable check-ppr
     Build-Depends: base       >= 4   && < 5,
                    bytestring,
                    containers,
-                   Cabal      >= 3.0 && < 3.6,
+                   Cabal      >= 3.2 && < 3.6,
                    directory,
                    filepath,
                    ghc
diff --git a/utils/ghc-cabal/ghc-cabal.cabal b/utils/ghc-cabal/ghc-cabal.cabal
index 5914c192e6..e00a812f32 100644
--- a/utils/ghc-cabal/ghc-cabal.cabal
+++ b/utils/ghc-cabal/ghc-cabal.cabal
@@ -21,6 +21,6 @@ Executable ghc-cabal
 
     Build-Depends: base       >= 3   && < 5,
                    bytestring >= 0.10 && < 0.11,
-                   Cabal      >= 3.0 && < 3.6,
+                   Cabal      >= 3.2 && < 3.6,
                    directory  >= 1.1 && < 1.4,
                    filepath   >= 1.2 && < 1.5