Turn on -XMonoLocalBinds by default (#18430)

And fix the resulting type errors.

Co-authored-by: Krzysztof Gogolewski <krz.gogolewski@gmail.com>

Metric Decrease:
    parsing001

7 files changed, 17 insertions, 11 deletions

diff --git a/compiler/GHC/CmmToAsm/Reg/Linear.hs b/compiler/GHC/CmmToAsm/Reg/Linear.hs
index 8d4da4bd2e..34e5e71205 100644
--- a/compiler/GHC/CmmToAsm/Reg/Linear.hs
+++ b/compiler/GHC/CmmToAsm/Reg/Linear.hs
@@ -205,7 +205,7 @@ regAlloc _ (CmmProc _ _ _ _)
 --   an entry in the block map or it is the first block.
 --
 linearRegAlloc
-        :: Instruction instr
+        :: forall instr. Instruction instr
         => NCGConfig
         -> [BlockId] -- ^ entry points
         -> BlockMap RegSet
@@ -231,6 +231,8 @@ linearRegAlloc config entry_ids block_live sccs
       ArchJavaScript -> panic "linearRegAlloc ArchJavaScript"
       ArchUnknown    -> panic "linearRegAlloc ArchUnknown"
  where
+  go :: (FR regs, Outputable regs)
+     => regs -> UniqSM ([NatBasicBlock instr], RegAllocStats, Int)
   go f = linearRegAlloc' config f entry_ids block_live sccs
   platform = ncgPlatform config
 
@@ -973,4 +975,3 @@ loadTemp vreg (ReadMem slot) hreg spills
 
 loadTemp _ _ _ spills =
    return spills
-
diff --git a/compiler/GHC/Core/Lint.hs b/compiler/GHC/Core/Lint.hs
index 9054ca086c..69cd263699 100644
--- a/compiler/GHC/Core/Lint.hs
+++ b/compiler/GHC/Core/Lint.hs
@@ -2290,6 +2290,7 @@ lintCoercion this@(AxiomRuleCo ax cos)
            Nothing -> err "Malformed use of AxiomRuleCo" [ ppr this ]
            Just _  -> return (AxiomRuleCo ax cos') }
   where
+  err :: forall a. String -> [SDoc] -> LintM a
   err m xs  = failWithL $
               hang (text m) 2 $ vcat (text "Rule:" <+> ppr (coaxrName ax) : xs)
 
diff --git a/compiler/GHC/Core/Opt/Simplify.hs b/compiler/GHC/Core/Opt/Simplify.hs
index 4895b312db..795605c557 100644
--- a/compiler/GHC/Core/Opt/Simplify.hs
+++ b/compiler/GHC/Core/Opt/Simplify.hs
@@ -1909,7 +1909,7 @@ completeCall env var cont
             log_inlining $
                 sep [text "Inlining done:", nest 4 (ppr var)]
       | otherwise
-      = liftIO $ log_inlining $
+      = log_inlining $
            sep [text "Inlining done: " <> ppr var,
                 nest 4 (vcat [text "Inlined fn: " <+> nest 2 (ppr unfolding),
                               text "Cont:  " <+> ppr cont])]
diff --git a/compiler/GHC/Driver/Make.hs b/compiler/GHC/Driver/Make.hs
index 9e7870c638..1fcc539384 100644
--- a/compiler/GHC/Driver/Make.hs
+++ b/compiler/GHC/Driver/Make.hs
@@ -1373,7 +1373,8 @@ parUpsweep_one mod home_mod_map comp_graph_loops lcl_dflags mHscMessage cleanup
 --
 -- There better had not be any cyclic groups here -- we check for them.
 upsweep
-    :: GhcMonad m
+    :: forall m
+     . GhcMonad m
     => Maybe Messager
     -> HomePackageTable            -- ^ HPT from last time round (pruned)
     -> StableModules               -- ^ stable modules (see checkStability)
@@ -1415,8 +1416,7 @@ upsweep mHscMessage old_hpt stable_mods cleanup sccs = do
     return (Failed, done')
 
   upsweep'
-    :: GhcMonad m
-    => HomePackageTable
+    :: HomePackageTable
     -> ModuleGraph
     -> [SCC ModSummary]
     -> Int
diff --git a/compiler/GHC/Runtime/Linker.hs b/compiler/GHC/Runtime/Linker.hs
index 4a3b03e5eb..6e0663b029 100644
--- a/compiler/GHC/Runtime/Linker.hs
+++ b/compiler/GHC/Runtime/Linker.hs
@@ -1134,6 +1134,7 @@ unload_wkr hsc_env keep_linkables pls@PersistentLinkerState{..}  = do
       -- Note that we want to remove all *local*
       -- (i.e. non-isExternal) names too (these are the
       -- temporary bindings from the command line).
+      keep_name :: (Name, a) -> Bool
       keep_name (n,_) = isExternalName n &&
                         nameModule n `elemModuleSet` bcos_retained
 
diff --git a/compiler/GHC/SysTools.hs b/compiler/GHC/SysTools.hs
index f3b4f4cc87..57d1757fe9 100644
--- a/compiler/GHC/SysTools.hs
+++ b/compiler/GHC/SysTools.hs
@@ -138,15 +138,17 @@ lazyInitLlvmConfig :: String
                -> IO LlvmConfig
 lazyInitLlvmConfig top_dir
   = unsafeInterleaveIO $ do    -- see Note [LLVM configuration]
-      targets <- readAndParse "llvm-targets" mkLlvmTarget
-      passes <- readAndParse "llvm-passes" id
-      return $ LlvmConfig { llvmTargets = targets, llvmPasses = passes }
+      targets <- readAndParse "llvm-targets"
+      passes <- readAndParse "llvm-passes"
+      return $ LlvmConfig { llvmTargets = fmap mkLlvmTarget <$> targets,
+                            llvmPasses = passes }
   where
-    readAndParse name builder =
+    readAndParse :: Read a => String -> IO a
+    readAndParse name =
       do let llvmConfigFile = top_dir </> name
          llvmConfigStr <- readFile llvmConfigFile
          case maybeReadFuzzy llvmConfigStr of
-           Just s -> return (fmap builder <$> s)
+           Just s -> return s
            Nothing -> pgmError ("Can't parse " ++ show llvmConfigFile)
 
     mkLlvmTarget :: (String, String, String) -> LlvmTarget
diff --git a/compiler/ghc.cabal.in b/compiler/ghc.cabal.in
index a05c101104..2a90db9c88 100644
--- a/compiler/ghc.cabal.in
+++ b/compiler/ghc.cabal.in
@@ -153,6 +153,7 @@ Library
         NoImplicitPrelude
        ,BangPatterns
        ,ScopedTypeVariables
+       ,MonoLocalBinds
 
     Exposed-Modules:
         GHC.Iface.Ext.Types