X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2Fghci%2FInteractiveUI.hs;h=4fb92692d130e1ca66a9555278dea53649cd8070;hp=9b0bdf956465f3a8de4444447fdac8a989781dde;hb=622e67a80631c7528ebfa51e9a863c27e74f1c6b;hpb=10406dfbd1a90e0ca813cc2809719263642d9a97

diff --git a/compiler/ghci/InteractiveUI.hs b/compiler/ghci/InteractiveUI.hs
index 9b0bdf9..4fb9269 100644
--- a/compiler/ghci/InteractiveUI.hs
+++ b/compiler/ghci/InteractiveUI.hs
@@ -74,6 +74,7 @@ import Data.Char
 import Data.Dynamic
 import Data.Array
 import Control.Monad as Monad
+import Text.Printf
 
 import Foreign.StablePtr	( newStablePtr )
 import GHC.Exts		( unsafeCoerce# )
@@ -108,7 +109,8 @@ builtin_commands = [
   ("browse",    keepGoing browseCmd,		False, completeModule),
   ("cd",    	keepGoing changeDirectory,	False, completeFilename),
   ("check",	keepGoing checkModule,		False, completeHomeModule),
-  ("continue",  continueCmd,                    False, completeNone),
+  ("continue",  keepGoing continueCmd,          False, completeNone),
+  ("cmd",       keepGoing cmdCmd,               False, completeIdentifier),
   ("ctags",	keepGoing createCTagsFileCmd, 	False, completeFilename),
   ("def",	keepGoing defineMacro,		False, completeIdentifier),
   ("delete",    keepGoing deleteCmd,            False, completeNone),
@@ -131,9 +133,9 @@ builtin_commands = [
   ("set",	keepGoing setCmd,		True,  completeSetOptions),
   ("show",	keepGoing showCmd,		False, completeNone),
   ("sprint",    keepGoing sprintCmd,            False, completeIdentifier),
-  ("step",      stepCmd,                        False, completeIdentifier), 
+  ("step",      keepGoing stepCmd,              False, completeIdentifier), 
   ("type",	keepGoing typeOfExpr,		False, completeIdentifier),
-  ("trace",     traceCmd,                       False, completeIdentifier), 
+  ("trace",     keepGoing traceCmd,             False, completeIdentifier), 
   ("undef",     keepGoing undefineMacro,	False, completeMacro),
   ("unset",	keepGoing unsetOptions,		True,  completeSetOptions)
   ]
@@ -149,31 +151,49 @@ shortHelpText = "use :? for help.\n"
 helpText =
  " Commands available from the prompt:\n" ++
  "\n" ++
- "   <stmt>                      evaluate/run <stmt>\n" ++
+ "   <statement>                 evaluate/run <statement>\n" ++
  "   :add <filename> ...         add module(s) to the current target set\n" ++
- "   :abandon                    at a breakpoint, abandon current computation\n" ++
- "   :break [<mod>] <l> [<col>]  set a breakpoint at the specified location\n" ++
- "   :break <name>               set a breakpoint on the specified function\n" ++
  "   :browse [*]<module>         display the names defined by <module>\n" ++
  "   :cd <dir>                   change directory to <dir>\n" ++
- "   :continue                   resume after a breakpoint\n" ++
+ "   :cmd <expr>                 run the commands returned by <expr>::IO String"++
  "   :ctags [<file>]             create tags file for Vi (default: \"tags\")\n" ++
  "   :def <cmd> <expr>           define a command :<cmd>\n" ++
- "   :delete <number>            delete the specified breakpoint\n" ++
- "   :delete *                   delete all breakpoints\n" ++
  "   :edit <file>                edit file\n" ++
  "   :edit                       edit last module\n" ++
  "   :etags [<file>]             create tags file for Emacs (default: \"TAGS\")\n" ++
--- "   :force <expr>               print <expr>, forcing unevaluated parts\n" ++
  "   :help, :?                   display this list of commands\n" ++
  "   :info [<name> ...]          display information about the given names\n" ++
  "   :kind <type>                show the kind of <type>\n" ++
  "   :load <filename> ...        load module(s) and their dependents\n" ++
  "   :module [+/-] [*]<mod> ...  set the context for expression evaluation\n" ++
  "   :main [<arguments> ...]     run the main function with the given arguments\n" ++
- "   :print [<name> ...]         prints a value without forcing its computation\n" ++
  "   :quit                       exit GHCi\n" ++
  "   :reload                     reload the current module set\n" ++
+ "   :type <expr>                show the type of <expr>\n" ++
+ "   :undef <cmd>                undefine user-defined command :<cmd>\n" ++
+ "   :!<command>                 run the shell command <command>\n" ++
+ "\n" ++
+ " -- Commands for debugging:\n" ++
+ "\n" ++
+ "   :abandon                    at a breakpoint, abandon current computation\n" ++
+ "   :back                       go back in the history (after :trace)\n" ++
+ "   :break [<mod>] <l> [<col>]  set a breakpoint at the specified location\n" ++
+ "   :break <name>               set a breakpoint on the specified function\n" ++
+ "   :continue                   resume after a breakpoint\n" ++
+ "   :delete <number>            delete the specified breakpoint\n" ++
+ "   :delete *                   delete all breakpoints\n" ++
+ "   :force <expr>               print <expr>, forcing unevaluated parts\n" ++
+ "   :forward                    go forward in the history (after :back)\n" ++
+ "   :history [<n>]              show the last <n> items in the history (after :trace)\n" ++
+ "   :print [<name> ...]         prints a value without forcing its computation\n" ++
+ "   :step                       single-step after stopping at a breakpoint\n"++
+ "   :step <expr>                single-step into <expr>\n"++
+ "   :trace                      trace after stopping at a breakpoint\n"++
+ "   :trace <expr>               trace into <expr> (remembers breakpoints for :history)\n"++
+ "   :sprint [<name> ...]        simplifed version of :print\n" ++
+
+ "\n" ++
+ " -- Commands for changing settings:\n" ++
  "\n" ++
  "   :set <option> ...           set options\n" ++
  "   :set args <arg> ...         set the arguments returned by System.getArgs\n" ++
@@ -181,29 +201,24 @@ helpText =
  "   :set prompt <prompt>        set the prompt used in GHCi\n" ++
  "   :set editor <cmd>           set the command used for :edit\n" ++
  "   :set stop <cmd>             set the command to run when a breakpoint is hit\n" ++
- "\n" ++
- "   :show breaks                show active breakpoints\n" ++
- "   :show context               show the breakpoint context\n" ++
- "   :show modules               show the currently loaded modules\n" ++
- "   :show bindings              show the current bindings made at the prompt\n" ++
- "\n" ++
- "   :sprint [<name> ...]        simplifed version of :print\n" ++
- "   :step                       single-step after stopping at a breakpoint\n"++
- "   :step <expr>                single-step into <expr>\n"++
- "   :type <expr>                show the type of <expr>\n" ++
- "   :undef <cmd>                undefine user-defined command :<cmd>\n" ++
  "   :unset <option> ...         unset options\n" ++
- "   :!<command>                 run the shell command <command>\n" ++
  "\n" ++
- " Options for ':set' and ':unset':\n" ++
+ "  Options for ':set' and ':unset':\n" ++
  "\n" ++
  "    +r            revert top-level expressions after each evaluation\n" ++
  "    +s            print timing/memory stats after each evaluation\n" ++
  "    +t            print type after evaluation\n" ++
  "    -<flags>      most GHC command line flags can also be set here\n" ++
  "                         (eg. -v2, -fglasgow-exts, etc.)\n" ++
+ "\n" ++
+ " -- Commands for displaying information:\n" ++
+ "\n" ++
+ "   :show bindings              show the current bindings made at the prompt\n" ++
+ "   :show breaks                show the active breakpoints\n" ++
+ "   :show context               show the breakpoint context\n" ++
+ "   :show modules               show the currently loaded modules\n" ++
+ "   :show <setting>             show anything that can be set with :set (e.g. args)\n" ++
  "\n" 
--- Todo: add help for breakpoint commands here
 
 findEditor = do
   getEnv "EDITOR" 
@@ -274,7 +289,8 @@ interactiveUI session srcs maybe_expr = do
                    prelude = prel_mod,
                    break_ctr = 0,
                    breaks = [],
-                   tickarrays = emptyModuleEnv
+                   tickarrays = emptyModuleEnv,
+                   cmdqueue = []
                  }
 
 #ifdef USE_READLINE
@@ -433,17 +449,9 @@ fileLoop hdl show_prompt = do
 	Right l -> 
 	  case removeSpaces l of
             "" -> fileLoop hdl show_prompt
-	    l  -> do quit <- runCommand l
+	    l  -> do quit <- runCommands l
                      if quit then return () else fileLoop hdl show_prompt
 
-stringLoop :: [String] -> GHCi Bool{-True: we quit-}
-stringLoop [] = return False
-stringLoop (s:ss) = do
-   case removeSpaces s of
-	"" -> stringLoop ss
-	l  -> do quit <- runCommand l
-                 if quit then return True else stringLoop ss
-
 mkPrompt = do
   session <- getSession
   (toplevs,exports) <- io (GHC.getContext session)
@@ -501,17 +509,31 @@ readlineLoop = do
 	    "" -> readlineLoop
 	    l  -> do
         	  io (addHistory l)
-  	  	  quit <- runCommand l
+  	  	  quit <- runCommands l
           	  if quit then return () else readlineLoop
 #endif
 
-runCommand :: String -> GHCi Bool
-runCommand c = ghciHandle handler (doCommand c)
-  where 
-    doCommand (':' : command) = specialCommand command
-    doCommand stmt
-       = do timeIt $ runStmt stmt GHC.RunToCompletion
-            return False
+runCommands :: String -> GHCi Bool
+runCommands cmd = do
+        q <- ghciHandle handler (doCommand cmd)
+        if q then return True else runNext
+  where
+       runNext = do
+          st <- getGHCiState
+          case cmdqueue st of
+            []   -> return False
+            c:cs -> do setGHCiState st{ cmdqueue = cs }
+                       runCommands c
+
+       doCommand (':' : cmd) = specialCommand cmd
+       doCommand stmt        = do timeIt $ runStmt stmt GHC.RunToCompletion
+                                  return False
+
+enqueueCommands :: [String] -> GHCi ()
+enqueueCommands cmds = do
+  st <- getGHCiState
+  setGHCiState st{ cmdqueue = cmds ++ cmdqueue st }
+
 
 -- This version is for the GHC command-line option -e.  The only difference
 -- from runCommand is that it catches the ExitException exception and
@@ -539,49 +561,47 @@ runStmt stmt step
       result <- io $ withProgName (progname st) $ withArgs (args st) $
 	     	     GHC.runStmt session stmt step
       afterRunStmt result
-      return False
 
 
-afterRunStmt :: GHC.RunResult -> GHCi (Maybe (Bool,[Name]))
+afterRunStmt :: GHC.RunResult -> GHCi Bool
+                                 -- False <=> the statement failed to compile
+afterRunStmt (GHC.RunException e) = throw e
 afterRunStmt run_result = do
-  mb_result <- switchOnRunResult run_result
-  -- possibly print the type and revert CAFs after evaluating an expression
-  show_types <- isOptionSet ShowType
   session <- getSession
-  case mb_result of
-    Nothing    -> return ()      
-    Just (is_break,names) -> 
-            when (is_break || show_types) $
-                  mapM_ (showTypeOfName session) names
-  
+  case run_result of
+     GHC.RunOk names -> do
+        show_types <- isOptionSet ShowType
+        when show_types $ mapM_ (showTypeOfName session) names
+     GHC.RunBreak _ names mb_info -> do
+        resumes <- io $ GHC.getResumeContext session
+        printForUser $ ptext SLIT("Stopped at") <+> 
+                       ppr (GHC.resumeSpan (head resumes))
+        mapM_ (showTypeOfName session) names
+        maybe (return ()) runBreakCmd mb_info
+        -- run the command set with ":set stop <cmd>"
+        st <- getGHCiState
+        enqueueCommands [stop st]
+        return ()
+     _ -> return ()
+
   flushInterpBuffers
   io installSignalHandlers
   b <- isOptionSet RevertCAFs
   io (when b revertCAFs)
 
-  return mb_result
-
-
-switchOnRunResult :: GHC.RunResult -> GHCi (Maybe (Bool,[Name]))
-switchOnRunResult GHC.RunFailed = return Nothing
-switchOnRunResult (GHC.RunException e) = throw e
-switchOnRunResult (GHC.RunOk names) = return $ Just (False,names)
-switchOnRunResult (GHC.RunBreak threadId names info) = do
-   session <- getSession
-   Just mod_info <- io $ GHC.getModuleInfo session (GHC.breakInfo_module info) 
-   let modBreaks  = GHC.modInfoModBreaks mod_info
-   let ticks      = GHC.modBreaks_locs modBreaks
-
-   -- display information about the breakpoint
-   let location = ticks ! GHC.breakInfo_number info
-   printForUser $ ptext SLIT("Stopped at") <+> ppr location
-
-   -- run the command set with ":set stop <cmd>"
-   st <- getGHCiState
-   runCommand (stop st)
-
-   return (Just (True,names))
+  return (case run_result of GHC.RunOk _ -> True; _ -> False)
 
+runBreakCmd :: GHC.BreakInfo -> GHCi ()
+runBreakCmd info = do
+  let mod = GHC.breakInfo_module info
+      nm  = GHC.breakInfo_number info
+  st <- getGHCiState
+  case  [ loc | (i,loc) <- breaks st,
+                breakModule loc == mod, breakTick loc == nm ] of
+        []  -> return ()
+        loc:_ | null cmd  -> return ()
+              | otherwise -> do enqueueCommands [cmd]; return ()
+              where cmd = onBreakCmd loc
 
 showTypeOfName :: Session -> Name -> GHCi ()
 showTypeOfName session n
@@ -675,8 +695,7 @@ pprInfo exts (thing, fixity, insts)
 runMain :: String -> GHCi ()
 runMain args = do
   let ss = concat $ intersperse "," (map (\ s -> ('"':s)++"\"") (toArgs args))
-  runCommand $ '[': ss ++ "] `System.Environment.withArgs` main"
-  return ()
+  enqueueCommands  ['[': ss ++ "] `System.Environment.withArgs` main"]
 
 addModule :: [FilePath] -> GHCi ()
 addModule files = do
@@ -749,7 +768,8 @@ defineMacro s = do
 runMacro :: GHC.HValue{-String -> IO String-} -> String -> GHCi Bool
 runMacro fun s = do
   str <- io ((unsafeCoerce# fun :: String -> IO String) s)
-  stringLoop (lines str)
+  enqueueCommands (lines str)
+  return False
 
 undefineMacro :: String -> GHCi ()
 undefineMacro macro_name = do
@@ -764,6 +784,17 @@ undefineMacro macro_name = do
 	else do
   io (writeIORef commands (filter ((/= macro_name) . cmdName) cmds))
 
+cmdCmd :: String -> GHCi ()
+cmdCmd str = do
+  let expr = '(' : str ++ ") :: IO String"
+  session <- getSession
+  maybe_hv <- io (GHC.compileExpr session expr)
+  case maybe_hv of
+    Nothing -> return ()
+    Just hv -> do 
+        cmds <- io $ (unsafeCoerce# hv :: IO String)
+        enqueueCommands (lines cmds)
+        return ()
 
 loadModule :: [(FilePath, Maybe Phase)] -> GHCi SuccessFlag
 loadModule fs = timeIt (loadModule' fs)
@@ -776,6 +807,7 @@ loadModule' files = do
   session <- getSession
 
   -- unload first
+  discardActiveBreakPoints
   io (GHC.setTargets session [])
   io (GHC.load session LoadAllTargets)
 
@@ -791,9 +823,7 @@ loadModule' files = do
   -- as a ToDo for now.
 
   io (GHC.setTargets session targets)
-  ok <- io (GHC.load session LoadAllTargets)
-  afterLoad ok session
-  return ok
+  doLoad session LoadAllTargets
 
 checkModule :: String -> GHCi ()
 checkModule m = do
@@ -816,19 +846,28 @@ checkModule m = do
 reloadModule :: String -> GHCi ()
 reloadModule "" = do
   io (revertCAFs)		-- always revert CAFs on reload.
+  discardActiveBreakPoints
   session <- getSession
-  ok <- io (GHC.load session LoadAllTargets)
-  afterLoad ok session
+  doLoad session LoadAllTargets
+  return ()
 reloadModule m = do
   io (revertCAFs)		-- always revert CAFs on reload.
+  discardActiveBreakPoints
   session <- getSession
-  ok <- io (GHC.load session (LoadUpTo (GHC.mkModuleName m)))
+  doLoad session (LoadUpTo (GHC.mkModuleName m))
+  return ()
+
+doLoad session howmuch = do
+  -- turn off breakpoints before we load: we can't turn them off later, because
+  -- the ModBreaks will have gone away.
+  discardActiveBreakPoints
+  ok <- io (GHC.load session howmuch)
   afterLoad ok session
+  return ok
 
 afterLoad ok session = do
   io (revertCAFs)  -- always revert CAFs on load.
   discardTickArrays
-  discardActiveBreakPoints
   graph <- io (GHC.getModuleGraph session)
   graph' <- filterM (io . GHC.isLoaded session . GHC.ms_mod_name) graph
   setContextAfterLoad session graph'
@@ -1057,6 +1096,19 @@ setEditor cmd = do
   st <- getGHCiState
   setGHCiState st{ editor = cmd }
 
+setStop str@(c:_) | isDigit c
+  = do let (nm_str,rest) = break (not.isDigit) str
+           nm = read nm_str
+       st <- getGHCiState
+       let old_breaks = breaks st
+       if all ((/= nm) . fst) old_breaks
+              then printForUser (text "Breakpoint" <+> ppr nm <+>
+                                 text "does not exist")
+              else do
+       let new_breaks = map fn old_breaks
+           fn (i,loc) | i == nm   = (i,loc { onBreakCmd = dropWhile isSpace rest })
+                      | otherwise = (i,loc)
+       setGHCiState st{ breaks = new_breaks }
 setStop cmd = do
   st <- getGHCiState
   setGHCiState st{ stop = cmd }
@@ -1074,8 +1126,10 @@ setOptions wds =
    do -- first, deal with the GHCi opts (+s, +t, etc.)
       let (plus_opts, minus_opts)  = partition isPlus wds
       mapM_ setOpt plus_opts
-
       -- then, dynamic flags
+      newDynFlags minus_opts
+
+newDynFlags minus_opts = do
       dflags <- getDynFlags
       let pkg_flags = packageFlags dflags
       (dflags',leftovers) <- io $ GHC.parseDynamicFlags dflags minus_opts
@@ -1113,10 +1167,11 @@ unsetOptions str
 
        mapM_ unsetOpt plus_opts
  
-       -- can't do GHC flags for now
-       if (not (null minus_opts))
-	  then throwDyn (CmdLineError "can't unset GHC command-line flags")
-	  else return ()
+       let no_flag ('-':'f':rest) = return ("-fno-" ++ rest)
+           no_flag f = throwDyn (ProgramError ("don't know how to reverse " ++ f))
+
+       no_flags <- mapM no_flag minus_opts
+       newDynFlags no_flags
 
 isMinus ('-':s) = True
 isMinus _ = False
@@ -1148,14 +1203,20 @@ optToStr RevertCAFs = "r"
 -- ---------------------------------------------------------------------------
 -- code for `:show'
 
-showCmd str =
+showCmd str = do
+  st <- getGHCiState
   case words str of
+        ["args"]     -> io $ putStrLn (show (args st))
+        ["prog"]     -> io $ putStrLn (show (progname st))
+        ["prompt"]   -> io $ putStrLn (show (prompt st))
+        ["editor"]   -> io $ putStrLn (show (editor st))
+        ["stop"]     -> io $ putStrLn (show (stop st))
 	["modules" ] -> showModules
 	["bindings"] -> showBindings
 	["linker"]   -> io showLinkerState
-        ["breaks"] -> showBkptTable
-        ["context"] -> showContext
-	_ -> throwDyn (CmdLineError "syntax:  :show [modules|bindings|breaks]")
+        ["breaks"]   -> showBkptTable
+        ["context"]  -> showContext
+	_ -> throwDyn (CmdLineError "syntax:  :show [args|prog|prompt|editor|stop|modules|bindings|breaks|context]")
 
 showModules = do
   session <- getSession
@@ -1433,26 +1494,23 @@ pprintCommand bind force str = do
   session <- getSession
   io $ pprintClosureCommand session bind force str
 
-stepCmd :: String -> GHCi Bool
+stepCmd :: String -> GHCi ()
 stepCmd []         = doContinue GHC.SingleStep
-stepCmd expression = runStmt expression GHC.SingleStep
+stepCmd expression = do runStmt expression GHC.SingleStep; return ()
 
-traceCmd :: String -> GHCi Bool
+traceCmd :: String -> GHCi ()
 traceCmd []         = doContinue GHC.RunAndLogSteps
-traceCmd expression = runStmt expression GHC.RunAndLogSteps
+traceCmd expression = do runStmt expression GHC.RunAndLogSteps; return ()
 
-continueCmd :: String -> GHCi Bool
-continueCmd [] = doContinue GHC.RunToCompletion
-continueCmd other = do
-   io $ putStrLn "The continue command accepts no arguments."
-   return False
+continueCmd :: String -> GHCi ()
+continueCmd = noArgs $ doContinue GHC.RunToCompletion
 
-doContinue :: SingleStep -> GHCi Bool
+doContinue :: SingleStep -> GHCi ()
 doContinue step = do 
   session <- getSession
   runResult <- io $ GHC.resume session step
   afterRunStmt runResult
-  return False
+  return ()
 
 abandonCmd :: String -> GHCi ()
 abandonCmd = noArgs $ do
@@ -1479,15 +1537,23 @@ deleteCmd argLine = do
          | otherwise = return ()
 
 historyCmd :: String -> GHCi ()
-historyCmd = noArgs $ do
-  s <- getSession
-  resumes <- io $ GHC.getResumeContext s
-  case resumes of
-    [] -> io $ putStrLn "Not stopped at a breakpoint"
-    (r:rs) -> do
-      let hist = GHC.resumeHistory r
-      spans <- mapM (io . GHC.getHistorySpan s) hist
-      printForUser (vcat (map ppr spans))
+historyCmd arg
+  | null arg        = history 20
+  | all isDigit arg = history (read arg)
+  | otherwise       = io $ putStrLn "Syntax:  :history [num]"
+  where
+  history num = do
+    s <- getSession
+    resumes <- io $ GHC.getResumeContext s
+    case resumes of
+      [] -> io $ putStrLn "Not stopped at a breakpoint"
+      (r:rs) -> do
+        let hist = GHC.resumeHistory r
+            (took,rest) = splitAt num hist
+        spans <- mapM (io . GHC.getHistorySpan s) took
+        let nums = map (printf "-%-3d:") [(1::Int)..]
+        printForUser (vcat (zipWith (<+>) (map text nums) (map ppr spans)))
+        io $ putStrLn $ if null rest then "<end of history>" else "..."
 
 backCmd :: String -> GHCi ()
 backCmd = noArgs $ do
@@ -1497,8 +1563,7 @@ backCmd = noArgs $ do
   mapM_ (showTypeOfName s) names
    -- run the command set with ":set stop <cmd>"
   st <- getGHCiState
-  runCommand (stop st)
-  return ()
+  enqueueCommands [stop st]
 
 forwardCmd :: String -> GHCi ()
 forwardCmd = noArgs $ do
@@ -1510,8 +1575,7 @@ forwardCmd = noArgs $ do
   mapM_ (showTypeOfName s) names
    -- run the command set with ":set stop <cmd>"
   st <- getGHCiState
-  runCommand (stop st)
-  return ()
+  enqueueCommands [stop st]
 
 -- handle the "break" command
 breakCmd :: String -> GHCi ()
@@ -1535,7 +1599,7 @@ breakSwitch session args@(arg1:rest)
               io $ putStrLn "Perhaps no modules are loaded for debugging?"
    | otherwise = do -- try parsing it as an identifier
         wantNameFromInterpretedModule noCanDo arg1 $ \name -> do
-        let loc = GHC.nameSrcLoc name
+        let loc = GHC.srcSpanStart (GHC.nameSrcSpan name)
         if GHC.isGoodSrcLoc loc
                then findBreakAndSet (GHC.nameModule name) $ 
                          findBreakByCoord (Just (GHC.srcLocFile loc))
@@ -1575,6 +1639,7 @@ findBreakAndSet mod lookupTickTree = do
                              { breakModule = mod
                              , breakLoc = span
                              , breakTick = tick
+                             , onBreakCmd = ""
                              }
                printForUser $
                   text "Breakpoint " <> ppr nm <>
@@ -1643,7 +1708,8 @@ listCmd "" = do
    mb_span <- getCurrentBreakSpan
    case mb_span of
       Nothing  -> printForUser $ text "not stopped at a breakpoint; nothing to list"
-      Just span -> io $ listAround span True
+      Just span | GHC.isGoodSrcSpan span -> io $ listAround span True
+                | otherwise              -> printForUser $ text "unable to list source for" <+> ppr span
 listCmd str = list2 (words str)
 
 list2 [arg] | all isDigit arg = do
@@ -1657,7 +1723,7 @@ list2 [arg1,arg2] | looksLikeModuleName arg1, all isDigit arg2 = do
         listModuleLine mod (read arg2)
 list2 [arg] = do
         wantNameFromInterpretedModule noCanDo arg $ \name -> do
-        let loc = GHC.nameSrcLoc name
+        let loc = GHC.srcSpanStart (GHC.nameSrcSpan name)
         if GHC.isGoodSrcLoc loc
                then do
                   tickArray <- getTickArray (GHC.nameModule name)
@@ -1758,7 +1824,7 @@ mkTickArray ticks
         [ (line, (nm,span)) | (nm,span) <- ticks,
                               line <- srcSpanLines span ]
     where
-        max_line = maximum (map GHC.srcSpanEndLine (map snd ticks))
+        max_line = foldr max 0 (map GHC.srcSpanEndLine (map snd ticks))
         srcSpanLines span = [ GHC.srcSpanStartLine span .. 
                               GHC.srcSpanEndLine span ]