Fix behaviour of -Wunused-packages in ghciwip/unused-package

Ticket #21110 points out that -Wunused-packages behaves a bit unusually
in GHCi. Now we define the semantics for -Wunused-packages in
interactive mode as follows:

* If you use -Wunused-packages on an initial load then the warning is reported.
* If you explicitly set -Wunused-packages on the command line then the
  warning is displayed (until it is disabled)
* If you then subsequently modify the set of available targets by using
  :load or :cd (:cd unloads everything) then the warning is (silently)
  turned off.

This means that every :r the warning is printed if it's turned on (but you did ask for it).

Fixes #21110

2 files changed, 25 insertions, 25 deletions

diff --git a/compiler/GHC/Driver/Env.hs b/compiler/GHC/Driver/Env.hs
index 8bc1f516bf..0d52ecc7cc 100644
--- a/compiler/GHC/Driver/Env.hs
+++ b/compiler/GHC/Driver/Env.hs
@@ -32,6 +32,7 @@ module GHC.Driver.Env
    , hptSomeThingsBelowUs
    , hptRules
    , prepareAnnotations
+   , discardIC
    , lookupType
    , lookupIfaceByModule
    , mainModIs
@@ -421,3 +422,27 @@ hscSetActiveUnitId uid e = e
 
 hscActiveUnitId :: HscEnv -> UnitId
 hscActiveUnitId e = ue_currentUnit (hsc_unit_env e)
+
+-- | Discard the contents of the InteractiveContext, but keep the DynFlags and
+-- the loaded plugins.  It will also keep ic_int_print and ic_monad if their
+-- names are from external packages.
+discardIC :: HscEnv -> HscEnv
+discardIC hsc_env
+  = hsc_env { hsc_IC = empty_ic { ic_int_print = new_ic_int_print
+                                , ic_monad     = new_ic_monad
+                                , ic_plugins   = old_plugins
+                                } }
+  where
+  -- Force the new values for ic_int_print and ic_monad to avoid leaking old_ic
+  !new_ic_int_print = keep_external_name ic_int_print
+  !new_ic_monad = keep_external_name ic_monad
+  !old_plugins = ic_plugins old_ic
+  dflags = ic_dflags old_ic
+  old_ic = hsc_IC hsc_env
+  empty_ic = emptyInteractiveContext dflags
+  keep_external_name ic_name
+    | nameIsFromExternalPackage home_unit old_name = old_name
+    | otherwise = ic_name empty_ic
+    where
+    home_unit = hsc_home_unit hsc_env
+    old_name = ic_name old_ic
diff --git a/compiler/GHC/Driver/Make.hs b/compiler/GHC/Driver/Make.hs
index bd4b4eeb57..38df5ecf26 100644
--- a/compiler/GHC/Driver/Make.hs
+++ b/compiler/GHC/Driver/Make.hs
@@ -61,7 +61,6 @@ import GHC.Runtime.Interpreter
 import qualified GHC.Linker.Loader as Linker
 import GHC.Linker.Types
 
-import GHC.Runtime.Context
 import GHC.Platform.Ways
 
 import GHC.Driver.Config.Finder (initFinderOpts)
@@ -107,7 +106,6 @@ import GHC.Types.SourceFile
 import GHC.Types.SourceError
 import GHC.Types.SrcLoc
 import GHC.Types.Unique.FM
-import GHC.Types.Name
 import GHC.Types.PkgQual
 
 import GHC.Unit
@@ -706,29 +704,6 @@ loadFinish all_ok
   = do modifySession discardIC
        return all_ok
 
--- | Discard the contents of the InteractiveContext, but keep the DynFlags and
--- the loaded plugins.  It will also keep ic_int_print and ic_monad if their
--- names are from external packages.
-discardIC :: HscEnv -> HscEnv
-discardIC hsc_env
-  = hsc_env { hsc_IC = empty_ic { ic_int_print = new_ic_int_print
-                                , ic_monad     = new_ic_monad
-                                , ic_plugins   = old_plugins
-                                } }
-  where
-  -- Force the new values for ic_int_print and ic_monad to avoid leaking old_ic
-  !new_ic_int_print = keep_external_name ic_int_print
-  !new_ic_monad = keep_external_name ic_monad
-  !old_plugins = ic_plugins old_ic
-  dflags = ic_dflags old_ic
-  old_ic = hsc_IC hsc_env
-  empty_ic = emptyInteractiveContext dflags
-  keep_external_name ic_name
-    | nameIsFromExternalPackage home_unit old_name = old_name
-    | otherwise = ic_name empty_ic
-    where
-    home_unit = hsc_home_unit hsc_env
-    old_name = ic_name old_ic
 
 -- | If there is no -o option, guess the name of target executable
 -- by using top-level source file name as a base.