2 % (c) The University of Glasgow 2006
3 % (c) The GRASP Project, Glasgow University, 1992-2000
6 Defines basic funtions for printing error messages.
8 It's hard to put these functions anywhere else without causing
9 some unnecessary loops in the module dependency graph.
14 GhcException(..), showGhcException, ghcError, progName,
17 panic, panic#, assertPanic, trace,
19 Exception.Exception(..), showException, try, tryJust, tryMost, tryUser,
20 catchJust, ioErrors, throwTo,
22 installSignalHandlers, interruptTargetThread
25 #include "HsVersions.h"
30 #ifndef mingw32_HOST_OS
31 import System.Posix.Signals
32 #endif /* mingw32_HOST_OS */
34 #if defined(mingw32_HOST_OS) && __GLASGOW_HASKELL__ >= 603
35 import GHC.ConsoleHandler
38 import Control.Exception
39 import Control.Concurrent ( MVar, ThreadId, withMVar, newMVar )
41 import qualified Control.Exception as Exception
42 import Debug.Trace ( trace )
43 import System.IO.Unsafe ( unsafePerformIO )
44 import System.IO.Error ( isUserError )
46 import System.Environment
49 GHC's own exception type.
52 ghcError :: GhcException -> a
53 ghcError e = Exception.throwDyn e
55 -- error messages all take the form
57 -- <location>: <error>
59 -- If the location is on the command line, or in GHC itself, then
60 -- <location>="ghc". All of the error types below correspond to
61 -- a <location> of "ghc", except for ProgramError (where the string is
62 -- assumed to contain a location already, so we don't print one).
65 = PhaseFailed String -- name of phase
66 ExitCode -- an external phase (eg. cpp) failed
67 | Interrupted -- someone pressed ^C
68 | UsageError String -- prints the short usage msg after the error
69 | CmdLineError String -- cmdline prob, but doesn't print usage
70 | Panic String -- the `impossible' happened
71 | InstallationError String -- an installation problem
72 | ProgramError String -- error in the user's code, probably
75 progName = unsafePerformIO (getProgName)
76 {-# NOINLINE progName #-}
78 short_usage = "Usage: For basic information, try the `--help' option."
80 showException :: Exception.Exception -> String
81 -- Show expected dynamic exceptions specially
82 showException (Exception.DynException d) | Just e <- fromDynamic d
83 = show (e::GhcException)
84 showException other_exn = show other_exn
86 instance Show GhcException where
87 showsPrec _ e@(ProgramError _) = showGhcException e
88 showsPrec _ e = showString progName . showString ": " . showGhcException e
90 showGhcException (UsageError str)
91 = showString str . showChar '\n' . showString short_usage
92 showGhcException (PhaseFailed phase code)
93 = showString "phase `" . showString phase .
94 showString "' failed (exitcode = " . shows int_code .
99 ExitSuccess -> (0::Int)
101 showGhcException (CmdLineError str)
103 showGhcException (ProgramError str)
105 showGhcException (InstallationError str)
107 showGhcException (Interrupted)
108 = showString "interrupted"
109 showGhcException (Panic s)
110 = showString ("panic! (the 'impossible' happened)\n"
111 ++ " (GHC version " ++ cProjectVersion ++ " for " ++ TargetPlatform_NAME ++ "):\n\t"
113 ++ "Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug\n")
115 #if __GLASGOW_HASKELL__ < 603
116 myMkTyConApp = mkAppTy
118 myMkTyConApp = mkTyConApp
121 ghcExceptionTc = mkTyCon "GhcException"
122 {-# NOINLINE ghcExceptionTc #-}
123 instance Typeable GhcException where
124 typeOf _ = myMkTyConApp ghcExceptionTc []
130 panic, pgmError :: String -> a
131 panic x = Exception.throwDyn (Panic x)
132 pgmError x = Exception.throwDyn (ProgramError x)
134 -- #-versions because panic can't return an unboxed int, and that's
135 -- what TAG_ is with GHC at the moment. Ugh. (Simon)
136 -- No, man -- Too Beautiful! (Will)
138 panic# :: String -> FastInt
139 panic# s = case (panic s) of () -> _ILIT 0
141 assertPanic :: String -> Int -> a
142 assertPanic file line =
143 Exception.throw (Exception.AssertionFailed
144 ("ASSERT failed! file " ++ file ++ ", line " ++ show line))
148 -- | tryMost is like try, but passes through Interrupted and Panic
149 -- exceptions. Used when we want soft failures when reading interface
150 -- files, for example.
152 tryMost :: IO a -> IO (Either Exception.Exception a)
153 tryMost action = do r <- try action; filter r
155 filter (Left e@(Exception.DynException d))
156 | Just ghc_ex <- fromDynamic d
158 Interrupted -> Exception.throw e
159 Panic _ -> Exception.throw e
160 _other -> return (Left e)
164 -- | tryUser is like try, but catches only UserErrors.
165 -- These are the ones that are thrown by the TcRn monad
166 -- to signal an error in the program being compiled
167 tryUser :: IO a -> IO (Either Exception.Exception a)
168 tryUser action = tryJust tc_errors action
170 tc_errors e@(Exception.IOException ioe) | isUserError ioe = Just e
171 tc_errors _other = Nothing
174 Standard signal handlers for catching ^C, which just throw an
175 exception in the target thread. The current target thread is
176 the thread at the head of the list in the MVar passed to
177 installSignalHandlers.
180 installSignalHandlers :: IO ()
181 installSignalHandlers = do
183 interrupt_exn = Exception.DynException (toDyn Interrupted)
186 withMVar interruptTargetThread $ \targets ->
189 (thread:_) -> throwTo thread interrupt_exn
191 #if !defined(mingw32_HOST_OS)
192 installHandler sigQUIT (Catch interrupt) Nothing
193 installHandler sigINT (Catch interrupt) Nothing
195 #elif __GLASGOW_HASKELL__ >= 603
196 -- GHC 6.3+ has support for console events on Windows
197 -- NOTE: running GHCi under a bash shell for some reason requires
198 -- you to press Ctrl-Break rather than Ctrl-C to provoke
199 -- an interrupt. Ctrl-C is getting blocked somewhere, I don't know
200 -- why --SDM 17/12/2004
201 let sig_handler ControlC = interrupt
202 sig_handler Break = interrupt
203 sig_handler _ = return ()
205 installHandler (Catch sig_handler)
211 {-# NOINLINE interruptTargetThread #-}
212 interruptTargetThread :: MVar [ThreadId]
213 interruptTargetThread = unsafePerformIO (newMVar [])