Add a flag -fno-ghci-history

Allows you to turn off loading/storing the GHCi command history from/to
the ~/.ghc/ghci_history file.

compiler/main/DynFlags.hs

@@ -278,6 +278,7 @@ data DynFlag
    | Opt_SSE2
    | Opt_SSE4_2
    | Opt_GhciSandbox
+   | Opt_GhciHistory
    | Opt_HelpfulErrors
 
 	-- temporary flags
@@ -1741,6 +1742,7 @@ fFlags = [
   ( "ext-core",                         AlwaysAllowed, Opt_EmitExternalCore, nop ),
   ( "shared-implib",                    AlwaysAllowed, Opt_SharedImplib, nop ),
   ( "ghci-sandbox",                     AlwaysAllowed, Opt_GhciSandbox, nop ),
+  ( "ghci-history",                     AlwaysAllowed, Opt_GhciHistory, nop ),
   ( "helpful-errors",                   AlwaysAllowed, Opt_HelpfulErrors, nop ),
   ( "building-cabal-package",           AlwaysAllowed, Opt_BuildingCabalPackage, nop ),
   ( "implicit-import-qualified",        AlwaysAllowed, Opt_ImplicitImportQualified, nop )
@@ -1916,6 +1918,7 @@ defaultFlags
       Opt_EmbedManifest,
       Opt_PrintBindContents,
       Opt_GhciSandbox,
+      Opt_GhciHistory,
       Opt_HelpfulErrors
     ]
 

docs/users_guide/flags.xml

@@ -2727,6 +2727,12 @@ phase <replaceable>n</replaceable></entry>
 	      <entry>static</entry>
 	      <entry>-</entry>
 	    </row>
+	    <row>
+	      <entry><option>-fno-ghci-history</option></entry>
+	      <entry>Do not use the load/store the GHCi command history from/to <literal>ghci_history</literal>.</entry>
+	      <entry>dynamic</entry>
+	      <entry>-</entry>
+	    </row>
 	    <row>
 	      <entry><option>-fno-ghci-sandbox</option></entry>
 	      <entry>Turn off the GHCi sandbox. Means computations are run in the main thread, rather than a forked thread.</entry>

ghc/InteractiveUI.hs

@@ -470,8 +470,11 @@ runGHCi paths maybe_exprs = do
 
 runGHCiInput :: InputT GHCi a -> GHCi a
 runGHCiInput f = do
-    histFile <- liftIO $ withGhcAppData (\dir -> return (Just (dir </> "ghci_history")))
-                                        (return Nothing)
+    dflags <- getDynFlags
+    histFile <- if dopt Opt_GhciHistory dflags
+                then liftIO $ withGhcAppData (\dir -> return (Just (dir </> "ghci_history")))
+                                             (return Nothing)
+                else return Nothing
     let settings = setComplete ghciCompleteWord
                     $ defaultSettings {historyFile = histFile}
     runInputT settings f