Fix a few new warnings when booting with GHC 9.2.2

-Wuni-incomplete-patterns and apparent improvements in the pattern match
checker surfaced these.

4 files changed, 18 insertions, 6 deletions

diff --git a/compiler/GHC/Linker/Loader.hs b/compiler/GHC/Linker/Loader.hs
index 8db50f0180..440780f544 100644
--- a/compiler/GHC/Linker/Loader.hs
+++ b/compiler/GHC/Linker/Loader.hs
@@ -622,12 +622,16 @@ dieWith dflags span msg = throwGhcExceptionIO (ProgramError (showSDoc dflags (mk
 
 
 checkNonStdWay :: DynFlags -> Interp -> SrcSpan -> IO (Maybe FilePath)
-checkNonStdWay dflags interp srcspan
+checkNonStdWay _dflags interp _srcspan
   | ExternalInterp {} <- interpInstance interp = return Nothing
     -- with -fexternal-interpreter we load the .o files, whatever way
     -- they were built.  If they were built for a non-std way, then
     -- we will use the appropriate variant of the iserv binary to load them.
 
+-- #if-guard the following equations otherwise the pattern match checker will
+-- complain that they are redundant.
+#if defined(HAVE_INTERNAL_INTERPRETER)
+checkNonStdWay dflags InternalInterp srcspan
   | hostFullWays == targetFullWays = return Nothing
     -- Only if we are compiling with the same ways as GHC is built
     -- with, can we dynamically load those object files. (see #3604)
@@ -642,8 +646,8 @@ checkNonStdWay dflags interp srcspan
                   "" -> ""
                   tag -> tag ++ "_"
 
-normalObjectSuffix :: String
-normalObjectSuffix = phaseInputExt StopLn
+    normalObjectSuffix :: String
+    normalObjectSuffix = phaseInputExt StopLn
 
 data Way' = Normal | Prof | Dyn
 
@@ -677,6 +681,7 @@ failNonStd dflags srcspan = dieWith dflags srcspan $
             Normal -> "the normal way"
             Prof -> "with -prof"
             Dyn -> "with -dynamic"
+#endif
 
 getLinkDeps :: HscEnv
             -> LoaderState
diff --git a/hadrian/src/Rules/SourceDist.hs b/hadrian/src/Rules/SourceDist.hs
index f37e26ade8..69941d5d5f 100644
--- a/hadrian/src/Rules/SourceDist.hs
+++ b/hadrian/src/Rules/SourceDist.hs
@@ -135,7 +135,10 @@ prepareTree dest = do
         let ctx = Context stg pkg vanilla
             srcInputFile = dest -/- pkgPath pkg -/- inp
             generatedFile = dest -/- pkgPath pkg -/- out
-            Just builder = determineBuilder stg inp
+            builder =
+                case determineBuilder stg inp of
+                  Just builder -> builder
+                  Nothing -> error $ "Failed to determine builder for " ++ inp
 
         -- We first make sure that the generated file is... generated.
         build $ target ctx builder [srcInputFile] [generatedFile]
diff --git a/utils/deriveConstants/Main.hs b/utils/deriveConstants/Main.hs
index 4832ccfc89..9a57ecf682 100644
--- a/utils/deriveConstants/Main.hs
+++ b/utils/deriveConstants/Main.hs
@@ -814,7 +814,7 @@ getWanted verbose os tmpdir gccProgram gccFlags nmProgram mobjdumpProgram
                   , Just sym <- stripPrefix prefix sym0 = Just (sym, read n)
                   | otherwise = Nothing
                 where
-                  [sym0, _] = take 2 (reverse $ words l1)
+                  sym0 = head $ reverse $ words l1
 
           -- If an Int value is larger than 2^28 or smaller
           -- than -2^28, then fail.
diff --git a/utils/genprimopcode/Main.hs b/utils/genprimopcode/Main.hs
index c4261e1e00..2bd12e117b 100644
--- a/utils/genprimopcode/Main.hs
+++ b/utils/genprimopcode/Main.hs
@@ -673,7 +673,11 @@ gen_primop_list (Info _ entries)
         map (\p -> "   , " ++ cons p) rest
         ++
         [     "   ]"     ]
-     ) where (first:rest) = concatMap desugarVectorSpec (filter is_primop entries)
+     ) where
+         (first,rest) =
+           case concatMap desugarVectorSpec (filter is_primop entries) of
+             x:xs -> (x,xs)
+             [] -> error "gen_primop_list: no primops"
 
 mIN_VECTOR_UNIQUE :: Int
 mIN_VECTOR_UNIQUE = 300