Add support for additional .ghci files in GHCi (#5265)

Patch by Sam Anklesaria <amsay@amsay.net>

compiler/main/DynFlags.hs

@@ -597,6 +597,7 @@ data DynFlags = DynFlags {
   flushErr              :: FlushErr,
 
   haddockOptions        :: Maybe String,
+  ghciScripts           :: [String],
 
   -- | what kind of {-# SCC #-} to add automatically
   profAuto              :: ProfAuto,
@@ -941,6 +942,7 @@ defaultDynFlags mySettings =
         haddockOptions = Nothing,
         flags = IntSet.fromList (map fromEnum defaultFlags),
         warningFlags = IntSet.fromList (map fromEnum standardWarnings),
+        ghciScripts = [],
         language = Nothing,
         safeHaskell = Sf_SafeInfered,
         thOnLoc = noSrcSpan,
@@ -1183,7 +1185,7 @@ setObjectDir, setHiDir, setStubDir, setDumpDir, setOutputDir,
          setDylibInstallName,
          setObjectSuf, setHiSuf, setHcSuf, parseDynLibLoaderMode,
          setPgmP, addOptl, addOptP,
-         addCmdlineFramework, addHaddockOpts
+         addCmdlineFramework, addHaddockOpts, addGhciScript
    :: String -> DynFlags -> DynFlags
 setOutputFile, setOutputHi, setDumpPrefixForce
    :: Maybe String -> DynFlags -> DynFlags
@@ -1255,6 +1257,8 @@ addCmdlineFramework f d = d{ cmdlineFrameworks = f : cmdlineFrameworks d}
 
 addHaddockOpts f d = d{ haddockOptions = Just f}
 
+addGhciScript f d = d{ ghciScripts = f : ghciScripts d}
+
 -- -----------------------------------------------------------------------------
 -- Command-line options
 
@@ -1545,6 +1549,7 @@ dynamic_flags = [
   , Flag "haddock"        (NoArg (setDynFlag Opt_Haddock))
   , Flag "haddock-opts"   (hasArg addHaddockOpts)
   , Flag "hpcdir"         (SepArg setOptHpcDir)
+  , Flag "ghci-script"    (hasArg addGhciScript)
 
         ------- recompilation checker --------------------------------------
   , Flag "recomp"         (NoArg (do unSetDynFlag Opt_ForceRecomp

docs/users_guide/flags.xml

@@ -492,6 +492,12 @@
             <entry>static</entry>
             <entry>-</entry>
           </row>
+          <row>
+            <entry><option>-ghci-script</option></entry>
+            <entry>Read additional <filename>.ghci</filename> files</entry>
+            <entry>dynamic</entry>
+            <entry>-</entry>
+          </row>
           <row>
             <entry><option>-read-dot-ghci</option></entry>
             <entry>Enable reading of <filename>.ghci</filename> files</entry>

docs/users_guide/ghci.xml

@@ -3105,6 +3105,10 @@ warning settings:
     wiki page: <ulink
       url="http://haskell.org/haskellwiki/GHC/GHCi">GHC/GHCi</ulink></para>
 
+	<para>Additionally, any files specified with
+    <literal>-ghci-script</literal> flags will be read after the
+    standard files, allowing the use of custom .ghci files.</para>
+
     <para>Two command-line options control whether the
     startup files files are read:</para>
 
@@ -3131,6 +3135,14 @@ warning settings:
 	  be used to override a previous
 	  <option>-ignore-dot-ghci</option> option.</para>
 	</listitem>
+	<term>
+         <option>-ghci-script</option>
+         <indexterm><primary><option>-ghci-script</option></primary></indexterm>
+    </term>
+	<listitem>
+	  <para>Read a specific file after the usual startup files.
+	  Maybe be specified repeatedly for multiple inputs.</para>
+	</listitem>
       </varlistentry>
     </variablelist>
 

ghc/InteractiveUI.hs

@@ -432,8 +432,9 @@ runGHCi paths maybe_exprs = do
 
   setGHCContextFromGHCiState
 
+  dflags <- getDynFlags
   when (read_dot_files) $ do
-    mcfgs0 <- sequence [ current_dir, app_user_dir, home_dir ]
+    mcfgs0 <- sequence $ [ current_dir, app_user_dir, home_dir ] ++ map (return . Just ) (ghciScripts dflags)
     mcfgs <- liftIO $ mapM canonicalizePath' (catMaybes mcfgs0)
     mapM_ sourceConfigFile $ nub $ catMaybes mcfgs
         -- nub, because we don't want to read .ghci twice if the
@@ -455,7 +456,6 @@ runGHCi paths maybe_exprs = do
   -- if verbosity is greater than 0, or we are connected to a
   -- terminal, display the prompt in the interactive loop.
   is_tty <- liftIO (hIsTerminalDevice stdin)
-  dflags <- getDynFlags
   let show_prompt = verbosity dflags > 0 || is_tty
 
   -- reset line number