Improve the error when :list can't find any code to show

[ghc-hetmet.git] / compiler / ghci / InteractiveUI.hs

diff --git a/compiler/ghci/InteractiveUI.hs b/compiler/ghci/InteractiveUI.hs
index e4439d6..30f1de6 100644 (file)
--- a/compiler/ghci/InteractiveUI.hs
+++ b/compiler/ghci/InteractiveUI.hs
@@ -54,6 +54,7 @@ import System.Posix hiding (getEnv)
 #else
 import GHC.ConsoleHandler ( flushConsole )
 import qualified System.Win32
+import System.FilePath
 #endif
 
 #ifdef USE_READLINE
@@ -158,11 +159,15 @@ builtin_commands = [
 -- 
 -- NOTE: in order for us to override the default correctly, any custom entry
 -- must be a SUBSET of word_break_chars.
-word_break_chars, flagWordBreakChars, filenameWordBreakChars :: String
+#ifdef USE_READLINE
+word_break_chars :: String
 word_break_chars = let symbols = "!#$%&*+/<=>?@\\^|-~"
                        specials = "(),;[]`{}"
                        spaces = " \t\n"
                    in spaces ++ specials ++ symbols
+#endif
+
+flagWordBreakChars, filenameWordBreakChars :: String
 flagWordBreakChars = " \t\n"
 filenameWordBreakChars = " \t\n\\`@$><=;|&{(" -- bash defaults
 
@@ -299,13 +304,15 @@ interactiveUI session srcs maybe_expr = do
         hSetBuffering stdin NoBuffering
 
 #ifdef USE_READLINE
-        Readline.initialize
-        Readline.setAttemptedCompletionFunction (Just completeWord)
-        --Readline.parseAndBind "set show-all-if-ambiguous 1"
-
-        Readline.setBasicWordBreakCharacters word_break_chars
-        Readline.setCompleterWordBreakCharacters word_break_chars
-        Readline.setCompletionAppendCharacter Nothing
+        is_tty <- hIsTerminalDevice stdin
+        when is_tty $ do
+            Readline.initialize
+            Readline.setAttemptedCompletionFunction (Just completeWord)
+            --Readline.parseAndBind "set show-all-if-ambiguous 1"
+
+            Readline.setBasicWordBreakCharacters word_break_chars
+            Readline.setCompleterWordBreakCharacters word_break_chars
+            Readline.setCompletionAppendCharacter Nothing
 #endif
 
    -- initial context is just the Prelude
@@ -2132,9 +2139,23 @@ listCmd :: String -> GHCi ()
 listCmd "" = do
    mb_span <- getCurrentBreakSpan
    case mb_span of
-      Nothing  -> printForUser $ text "not stopped at a breakpoint; nothing to list"
-      Just span | GHC.isGoodSrcSpan span -> io $ listAround span True
-                | otherwise              -> printForUser $ text "unable to list source for" <+> ppr span
+      Nothing ->
+          printForUser $ text "Not stopped at a breakpoint; nothing to list"
+      Just span
+       | GHC.isGoodSrcSpan span -> io $ listAround span True
+       | otherwise ->
+          do s <- getSession
+             resumes <- io $ GHC.getResumeContext s
+             case resumes of
+                 [] -> panic "No resumes"
+                 (r:_) ->
+                     do let traceIt = case GHC.resumeHistory r of
+                                      [] -> text "rerunning with :trace,"
+                                      _ -> empty
+                            doWhat = traceIt <+> text ":back then :list"
+                        printForUser (text "Unable to list source for" <+>
+                                      ppr span
+                                   $$ text "Try" <+> doWhat)
 listCmd str = list2 (words str)
 
 list2 :: [String] -> GHCi ()