Remove unused imports of the form 'import foo ()' (Fixes #17065)

These kinds of imports are necessary in some cases such as
importing instances of typeclasses or intentionally creating
dependencies in the build system, but '-Wunused-imports' can't
detect when they are no longer needed. This commit removes the
unused ones currently in the code base (not including test files
or submodules), with the hope that doing so may increase
parallelism in the build system by removing unnecessary
dependencies.

10 files changed, 5 insertions, 12 deletions

diff --git a/compiler/cmm/CmmBuildInfoTables.hs b/compiler/cmm/CmmBuildInfoTables.hs
index 90d15aeea7..9c05a8fe29 100644
--- a/compiler/cmm/CmmBuildInfoTables.hs
+++ b/compiler/cmm/CmmBuildInfoTables.hs
@@ -19,7 +19,6 @@ import Module
 import GHC.Platform
 import Digraph
 import CLabel
-import PprCmmDecl ()
 import Cmm
 import CmmUtils
 import DynFlags
@@ -30,7 +29,6 @@ import UniqSupply
 import CostCentre
 import StgCmmHeap
 
-import PprCmm()
 import Control.Monad
 import Data.Map (Map)
 import qualified Data.Map as Map
diff --git a/compiler/cmm/CmmCallConv.hs b/compiler/cmm/CmmCallConv.hs
index 4e6a9d293a..df1eaad005 100644
--- a/compiler/cmm/CmmCallConv.hs
+++ b/compiler/cmm/CmmCallConv.hs
@@ -10,7 +10,7 @@ import GhcPrelude
 import CmmExpr
 import SMRep
 import Cmm (Convention(..))
-import PprCmm ()
+import PprCmm () -- For Outputable instances
 
 import DynFlags
 import GHC.Platform
diff --git a/compiler/cmm/CmmCommonBlockElim.hs b/compiler/cmm/CmmCommonBlockElim.hs
index b43d68970f..cbf7d83d36 100644
--- a/compiler/cmm/CmmCommonBlockElim.hs
+++ b/compiler/cmm/CmmCommonBlockElim.hs
@@ -13,7 +13,6 @@ import Cmm
 import CmmUtils
 import CmmSwitch (eqSwitchTargetWith)
 import CmmContFlowOpt
--- import PprCmm ()
 
 import Hoopl.Block
 import Hoopl.Graph
diff --git a/compiler/cmm/CmmLint.hs b/compiler/cmm/CmmLint.hs
index d5c3f84443..3ad65bd536 100644
--- a/compiler/cmm/CmmLint.hs
+++ b/compiler/cmm/CmmLint.hs
@@ -21,7 +21,7 @@ import Cmm
 import CmmUtils
 import CmmLive
 import CmmSwitch (switchTargetsToList)
-import PprCmm ()
+import PprCmm () -- For Outputable instances
 import Outputable
 import DynFlags
 
diff --git a/compiler/cmm/CmmLive.hs b/compiler/cmm/CmmLive.hs
index f340c32c8a..ca474ef61c 100644
--- a/compiler/cmm/CmmLive.hs
+++ b/compiler/cmm/CmmLive.hs
@@ -17,7 +17,7 @@ import GhcPrelude
 import DynFlags
 import BlockId
 import Cmm
-import PprCmmExpr ()
+import PprCmmExpr () -- For Outputable instances
 import Hoopl.Block
 import Hoopl.Collections
 import Hoopl.Dataflow
diff --git a/compiler/cmm/CmmProcPoint.hs b/compiler/cmm/CmmProcPoint.hs
index 528337c57e..746a175cfe 100644
--- a/compiler/cmm/CmmProcPoint.hs
+++ b/compiler/cmm/CmmProcPoint.hs
@@ -14,7 +14,7 @@ import DynFlags
 import BlockId
 import CLabel
 import Cmm
-import PprCmm ()
+import PprCmm () -- For Outputable instances
 import CmmUtils
 import CmmInfo
 import CmmLive
diff --git a/compiler/cmm/CmmSink.hs b/compiler/cmm/CmmSink.hs
index 409cd0fbf2..8a6b120377 100644
--- a/compiler/cmm/CmmSink.hs
+++ b/compiler/cmm/CmmSink.hs
@@ -19,7 +19,6 @@ import GHC.Platform (isARM, platformArch)
 import DynFlags
 import Unique
 import UniqFM
-import PprCmm ()
 
 import qualified Data.IntSet as IntSet
 import Data.List (partition)
diff --git a/compiler/cmm/Debug.hs b/compiler/cmm/Debug.hs
index da37495530..4aec63fad6 100644
--- a/compiler/cmm/Debug.hs
+++ b/compiler/cmm/Debug.hs
@@ -32,7 +32,6 @@ import CoreSyn
 import FastString      ( nilFS, mkFastString )
 import Module
 import Outputable
-import PprCore         ()
 import PprCmmExpr      ( pprExpr )
 import SrcLoc
 import Util            ( seqList )
diff --git a/compiler/cmm/PprC.hs b/compiler/cmm/PprC.hs
index 7227edd57e..d412969ca7 100644
--- a/compiler/cmm/PprC.hs
+++ b/compiler/cmm/PprC.hs
@@ -32,7 +32,7 @@ import BlockId
 import CLabel
 import ForeignCall
 import Cmm hiding (pprBBlock)
-import PprCmm ()
+import PprCmm () -- For Outputable instances
 import Hoopl.Block
 import Hoopl.Collections
 import Hoopl.Graph
diff --git a/compiler/cmm/PprCmm.hs b/compiler/cmm/PprCmm.hs
index 90f26e4247..397a666022 100644
--- a/compiler/cmm/PprCmm.hs
+++ b/compiler/cmm/PprCmm.hs
@@ -41,7 +41,6 @@ where
 
 import GhcPrelude hiding (succ)
 
-import BlockId ()
 import CLabel
 import Cmm
 import CmmUtils
@@ -52,7 +51,6 @@ import Outputable
 import PprCmmDecl
 import PprCmmExpr
 import Util
-import PprCore ()
 
 import BasicTypes
 import Hoopl.Block