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.

12 files changed, 6 insertions, 15 deletions

diff --git a/compiler/nativeGen/BlockLayout.hs b/compiler/nativeGen/BlockLayout.hs
index 8904b4113b..3755ed5db6 100644
--- a/compiler/nativeGen/BlockLayout.hs
+++ b/compiler/nativeGen/BlockLayout.hs
@@ -37,7 +37,6 @@ import Maybes
 --import Debug
 --import Debug.Trace
 import ListSetOps (removeDups)
-import PprCmm ()
 
 import OrdList
 import Data.List
diff --git a/compiler/nativeGen/CFG.hs b/compiler/nativeGen/CFG.hs
index af0c6da455..44ddecd216 100644
--- a/compiler/nativeGen/CFG.hs
+++ b/compiler/nativeGen/CFG.hs
@@ -56,7 +56,7 @@ import Outputable
 --import Debug
 --import OrdList
 --import Debug.Trace
-import PprCmm ()
+import PprCmm () -- For Outputable instances
 import qualified DynFlags as D
 
 import Data.List
diff --git a/compiler/nativeGen/PPC/Ppr.hs b/compiler/nativeGen/PPC/Ppr.hs
index 4254f23122..0c3aaccda2 100644
--- a/compiler/nativeGen/PPC/Ppr.hs
+++ b/compiler/nativeGen/PPC/Ppr.hs
@@ -27,7 +27,7 @@ import Hoopl.Label
 
 import BlockId
 import CLabel
-import PprCmmExpr ()
+import PprCmmExpr () -- For Outputable instances
 
 import Unique                ( pprUniqueAlways, getUnique )
 import GHC.Platform
diff --git a/compiler/nativeGen/RegAlloc/Graph/Stats.hs b/compiler/nativeGen/RegAlloc/Graph/Stats.hs
index 487e3ee03a..f765224072 100644
--- a/compiler/nativeGen/RegAlloc/Graph/Stats.hs
+++ b/compiler/nativeGen/RegAlloc/Graph/Stats.hs
@@ -28,7 +28,6 @@ import RegClass
 import Reg
 import TargetReg
 
-import PprCmm()
 import Outputable
 import UniqFM
 import UniqSet
diff --git a/compiler/nativeGen/RegAlloc/Liveness.hs b/compiler/nativeGen/RegAlloc/Liveness.hs
index bbb7976a75..3f160ea678 100644
--- a/compiler/nativeGen/RegAlloc/Liveness.hs
+++ b/compiler/nativeGen/RegAlloc/Liveness.hs
@@ -45,7 +45,6 @@ import CFG
 import Hoopl.Collections
 import Hoopl.Label
 import Cmm hiding (RegSet, emptyRegSet)
-import PprCmm()
 
 import Digraph
 import DynFlags
diff --git a/compiler/nativeGen/SPARC/CodeGen.hs b/compiler/nativeGen/SPARC/CodeGen.hs
index 056d0c6fbf..bb8bbe16b6 100644
--- a/compiler/nativeGen/SPARC/CodeGen.hs
+++ b/compiler/nativeGen/SPARC/CodeGen.hs
@@ -31,7 +31,6 @@ import SPARC.CodeGen.CondCode
 import SPARC.CodeGen.Gen64
 import SPARC.CodeGen.Gen32
 import SPARC.CodeGen.Base
-import SPARC.Ppr        ()
 import SPARC.Instr
 import SPARC.Imm
 import SPARC.AddrMode
diff --git a/compiler/nativeGen/SPARC/CodeGen/Base.hs b/compiler/nativeGen/SPARC/CodeGen/Base.hs
index e64af0c44e..97c54a9364 100644
--- a/compiler/nativeGen/SPARC/CodeGen/Base.hs
+++ b/compiler/nativeGen/SPARC/CodeGen/Base.hs
@@ -25,7 +25,7 @@ import Reg
 import CodeGen.Platform
 import DynFlags
 import Cmm
-import PprCmmExpr ()
+import PprCmmExpr () -- For Outputable instances
 import GHC.Platform
 
 import Outputable
diff --git a/compiler/nativeGen/SPARC/CodeGen/Expand.hs b/compiler/nativeGen/SPARC/CodeGen/Expand.hs
index 0b318740db..a29c24dcd4 100644
--- a/compiler/nativeGen/SPARC/CodeGen/Expand.hs
+++ b/compiler/nativeGen/SPARC/CodeGen/Expand.hs
@@ -11,7 +11,6 @@ import SPARC.Instr
 import SPARC.Imm
 import SPARC.AddrMode
 import SPARC.Regs
-import SPARC.Ppr        ()
 import Instruction
 import Reg
 import Format
diff --git a/compiler/nativeGen/SPARC/CodeGen/Gen64.hs b/compiler/nativeGen/SPARC/CodeGen/Gen64.hs
index 6fa7482f9b..18df9e19a3 100644
--- a/compiler/nativeGen/SPARC/CodeGen/Gen64.hs
+++ b/compiler/nativeGen/SPARC/CodeGen/Gen64.hs
@@ -16,7 +16,7 @@ import SPARC.Regs
 import SPARC.AddrMode
 import SPARC.Imm
 import SPARC.Instr
-import SPARC.Ppr()
+-- import SPARC.Ppr()
 import NCGMonad
 import Instruction
 import Format
diff --git a/compiler/nativeGen/SPARC/CodeGen/Sanity.hs b/compiler/nativeGen/SPARC/CodeGen/Sanity.hs
index fcf5b65bde..7f9bfed229 100644
--- a/compiler/nativeGen/SPARC/CodeGen/Sanity.hs
+++ b/compiler/nativeGen/SPARC/CodeGen/Sanity.hs
@@ -9,7 +9,7 @@ where
 import GhcPrelude
 
 import SPARC.Instr
-import SPARC.Ppr        ()
+import SPARC.Ppr        () -- For Outputable instances
 import Instruction
 
 import Cmm
diff --git a/compiler/nativeGen/SPARC/Ppr.hs b/compiler/nativeGen/SPARC/Ppr.hs
index fc67f77541..2bec7ec01f 100644
--- a/compiler/nativeGen/SPARC/Ppr.hs
+++ b/compiler/nativeGen/SPARC/Ppr.hs
@@ -39,7 +39,7 @@ import Format
 import PprBase
 
 import Cmm hiding (topInfoTable)
-import PprCmm()
+import PprCmm() -- For Outputable instances
 import BlockId
 import CLabel
 import Hoopl.Label
diff --git a/compiler/nativeGen/X86/CodeGen.hs b/compiler/nativeGen/X86/CodeGen.hs
index 13662f6807..4aeb4eb635 100644
--- a/compiler/nativeGen/X86/CodeGen.hs
+++ b/compiler/nativeGen/X86/CodeGen.hs
@@ -38,9 +38,6 @@ import X86.Cond
 import X86.Regs
 import X86.RegInfo
 
---TODO: Remove - Just for development/debugging
-import X86.Ppr()
-
 import CodeGen.Platform
 import CPrim
 import Debug            ( DebugBlock(..), UnwindPoint(..), UnwindTable
@@ -60,7 +57,6 @@ import GHC.Platform
 import BasicTypes
 import BlockId
 import Module           ( primUnitId )
-import PprCmm           ()
 import CmmUtils
 import CmmSwitch
 import Cmm