Cabal: Disable GHCi libraries on Windows with GHC >=9.4

As noted in #21068, the lld linker used on Windows by GHC 9.4 and later
does not support object merging. Consequently, --enable-library-for-ghci
can no longer be supported on this platform.

Author: bgamari

Cabal/src/Distribution/Simple/Configure.hs

@@ -635,6 +635,22 @@ configure (pkg_descr0, pbi) cfg = do
                                       "--enable-split-objs; ignoring")
                                 return False
 
+    let compilerSupportsGhciLibs :: Bool
+        compilerSupportsGhciLibs =
+          case compilerId comp of
+            CompilerId GHC version
+              | version > mkVersion [9,3] && windows ->
+                False
+            CompilerId GHC _ ->
+                True
+            CompilerId GHCJS _ ->
+                True
+            _ -> False
+          where
+            windows = case compPlatform of
+              Platform _ Windows -> True
+              Platform _ _ -> False
+
     let ghciLibByDefault =
           case compilerId comp of
             CompilerId GHC _ ->
@@ -651,6 +667,15 @@ configure (pkg_descr0, pbi) cfg = do
               not (GHCJS.isDynamic comp)
             _ -> False
 
+    withGHCiLib_ <-
+      case fromFlagOrDefault ghciLibByDefault (configGHCiLib cfg) of
+        True | not compilerSupportsGhciLibs -> do
+          warn verbosity $
+                "--enable-library-for-ghci is no longer supported on Windows with"
+              ++ "GHC 9.4 and later; ignoring..."
+          return False
+        v -> return v
+
     let sharedLibsByDefault
           | fromFlag (configDynExe cfg) =
               -- build a shared library if dynamically-linked
@@ -747,8 +772,7 @@ configure (pkg_descr0, pbi) cfg = do
                 withProfExeDetail   = ProfDetailNone,
                 withOptimization    = fromFlag $ configOptimization cfg,
                 withDebugInfo       = fromFlag $ configDebugInfo cfg,
-                withGHCiLib         = fromFlagOrDefault ghciLibByDefault $
-                                      configGHCiLib cfg,
+                withGHCiLib         = withGHCiLib_,
                 splitSections       = split_sections,
                 splitObjs           = split_objs,
                 stripExes           = strip_exe,