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, throwGhcException, handleGhcException,
18 panic, panicFastInt, assertPanic, trace,
20 Exception.Exception(..), showException, try, tryMost, tryUser, 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)
35 import GHC.ConsoleHandler
39 import Control.Concurrent ( MVar, ThreadId, withMVar, newMVar )
41 import Debug.Trace ( trace )
42 import System.IO.Unsafe ( unsafePerformIO )
43 import System.IO.Error hiding ( try )
45 import System.Environment
48 GHC's own exception type.
51 ghcError :: GhcException -> a
52 ghcError e = Exception.throw e
54 -- error messages all take the form
56 -- <location>: <error>
58 -- If the location is on the command line, or in GHC itself, then
59 -- <location>="ghc". All of the error types below correspond to
60 -- a <location> of "ghc", except for ProgramError (where the string is
61 -- assumed to contain a location already, so we don't print one).
64 = PhaseFailed String -- name of phase
65 ExitCode -- an external phase (eg. cpp) failed
66 | Interrupted -- someone pressed ^C
67 | UsageError String -- prints the short usage msg after the error
68 | CmdLineError String -- cmdline prob, but doesn't print usage
69 | Panic String -- the `impossible' happened
70 | InstallationError String -- an installation problem
71 | ProgramError String -- error in the user's code, probably
74 instance Exception GhcException
77 progName = unsafePerformIO (getProgName)
78 {-# NOINLINE progName #-}
81 short_usage = "Usage: For basic information, try the `--help' option."
83 showException :: Exception e => e -> String
86 instance Show GhcException where
87 showsPrec _ e@(ProgramError _) = showGhcException e
88 showsPrec _ e@(CmdLineError _) = showString "<command line>: " . showGhcException e
89 showsPrec _ e = showString progName . showString ": " . showGhcException e
91 showGhcException :: GhcException -> String -> String
92 showGhcException (UsageError str)
93 = showString str . showChar '\n' . showString short_usage
94 showGhcException (PhaseFailed phase code)
95 = showString "phase `" . showString phase .
96 showString "' failed (exitcode = " . shows int_code .
101 ExitSuccess -> (0::Int)
103 showGhcException (CmdLineError str)
105 showGhcException (ProgramError str)
107 showGhcException (InstallationError str)
109 showGhcException (Interrupted)
110 = showString "interrupted"
111 showGhcException (Panic s)
112 = showString ("panic! (the 'impossible' happened)\n"
113 ++ " (GHC version " ++ cProjectVersion ++ " for " ++ TargetPlatform_NAME ++ "):\n\t"
115 ++ "Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug\n")
117 throwGhcException :: GhcException -> a
118 throwGhcException = Exception.throw
120 handleGhcException :: ExceptionMonad m => (GhcException -> m a) -> m a -> m a
121 handleGhcException = ghandle
123 ghcExceptionTc :: TyCon
124 ghcExceptionTc = mkTyCon "GhcException"
125 {-# NOINLINE ghcExceptionTc #-}
126 instance Typeable GhcException where
127 typeOf _ = mkTyConApp ghcExceptionTc []
133 panic, pgmError :: String -> a
134 panic x = throwGhcException (Panic x)
135 pgmError x = throwGhcException (ProgramError x)
137 -- #-versions because panic can't return an unboxed int, and that's
138 -- what TAG_ is with GHC at the moment. Ugh. (Simon)
139 -- No, man -- Too Beautiful! (Will)
141 panicFastInt :: String -> FastInt
142 panicFastInt s = case (panic s) of () -> _ILIT(0)
144 assertPanic :: String -> Int -> a
145 assertPanic file line =
146 Exception.throw (Exception.AssertionFailed
147 ("ASSERT failed! file " ++ file ++ ", line " ++ show line))
151 -- | tryMost is like try, but passes through Interrupted and Panic
152 -- exceptions. Used when we want soft failures when reading interface
153 -- files, for example.
155 -- XXX I'm not entirely sure if this is catching what we really want to catch
156 tryMost :: IO a -> IO (Either SomeException a)
157 tryMost action = do r <- try action
160 case fromException se of
161 -- Some GhcException's we rethrow,
162 Just Interrupted -> throwIO se
163 Just (Panic _) -> throwIO se
165 Just _ -> return (Left se)
167 case fromException se of
168 -- All IOExceptions are returned
169 Just (_ :: IOException) ->
171 -- Anything else is rethrown
172 Nothing -> throwIO se
173 Right v -> return (Right v)
175 -- | tryUser is like try, but catches only UserErrors.
176 -- These are the ones that are thrown by the TcRn monad
177 -- to signal an error in the program being compiled
178 tryUser :: IO a -> IO (Either IOException a)
182 Right v -> return (Right v)
184 case fromException se of
191 Standard signal handlers for catching ^C, which just throw an
192 exception in the target thread. The current target thread is
193 the thread at the head of the list in the MVar passed to
194 installSignalHandlers.
197 installSignalHandlers :: IO ()
198 installSignalHandlers = do
200 interrupt_exn = (toException Interrupted)
203 withMVar interruptTargetThread $ \targets ->
206 (thread:_) -> throwTo thread interrupt_exn
208 #if !defined(mingw32_HOST_OS)
209 installHandler sigQUIT (Catch interrupt) Nothing
210 installHandler sigINT (Catch interrupt) Nothing
213 -- GHC 6.3+ has support for console events on Windows
214 -- NOTE: running GHCi under a bash shell for some reason requires
215 -- you to press Ctrl-Break rather than Ctrl-C to provoke
216 -- an interrupt. Ctrl-C is getting blocked somewhere, I don't know
217 -- why --SDM 17/12/2004
218 let sig_handler ControlC = interrupt
219 sig_handler Break = interrupt
220 sig_handler _ = return ()
222 installHandler (Catch sig_handler)
226 {-# NOINLINE interruptTargetThread #-}
227 interruptTargetThread :: MVar [ThreadId]
228 interruptTargetThread = unsafePerformIO (newMVar [])