2 % (c) The GRASP Project, Glasgow University, 1992-2000
4 \section{Panic error messages}
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 # if __GLASGOW_HASKELL__ > 504
32 import System.Posix.Signals
34 import Posix ( Handler(Catch), installHandler, sigINT, sigQUIT )
35 # endif /* GHC > 504 */
36 #endif /* mingw32_HOST_OS */
38 #if defined(mingw32_HOST_OS) && __GLASGOW_HASKELL__ >= 603
39 import GHC.ConsoleHandler
42 # if __GLASGOW_HASKELL__ < 500
43 import EXCEPTION ( raiseInThread )
45 import EXCEPTION ( throwTo )
46 # endif /* GHC < 500 */
48 #if __GLASGOW_HASKELL__ > 408
49 import EXCEPTION ( catchJust, tryJust, ioErrors )
52 import CONCURRENT ( myThreadId, MVar, ThreadId, withMVar, newEmptyMVar )
54 import qualified EXCEPTION as Exception
55 import TRACE ( trace )
56 import UNSAFE_IO ( unsafePerformIO )
57 import IO ( isUserError )
62 GHC's own exception type.
65 ghcError :: GhcException -> a
66 ghcError e = Exception.throwDyn e
68 -- error messages all take the form
70 -- <location>: <error>
72 -- If the location is on the command line, or in GHC itself, then
73 -- <location>="ghc". All of the error types below correspond to
74 -- a <location> of "ghc", except for ProgramError (where the string is
75 -- assumed to contain a location already, so we don't print one).
78 = PhaseFailed String -- name of phase
79 ExitCode -- an external phase (eg. cpp) failed
80 | Interrupted -- someone pressed ^C
81 | UsageError String -- prints the short usage msg after the error
82 | CmdLineError String -- cmdline prob, but doesn't print usage
83 | Panic String -- the `impossible' happened
84 | InstallationError String -- an installation problem
85 | ProgramError String -- error in the user's code, probably
88 progName = unsafePerformIO (getProgName)
89 {-# NOINLINE progName #-}
91 short_usage = "Usage: For basic information, try the `--help' option."
93 showException :: Exception.Exception -> String
94 -- Show expected dynamic exceptions specially
95 showException (Exception.DynException d) | Just e <- fromDynamic d
96 = show (e::GhcException)
97 showException other_exn = show other_exn
99 instance Show GhcException where
100 showsPrec _ e@(ProgramError _) = showGhcException e
101 showsPrec _ e = showString progName . showString ": " . showGhcException e
103 showGhcException (UsageError str)
104 = showString str . showChar '\n' . showString short_usage
105 showGhcException (PhaseFailed phase code)
106 = showString "phase `" . showString phase .
107 showString "' failed (exitcode = " . shows int_code .
112 ExitSuccess -> (0::Int)
114 showGhcException (CmdLineError str)
116 showGhcException (ProgramError str)
118 showGhcException (InstallationError str)
120 showGhcException (Interrupted)
121 = showString "interrupted"
122 showGhcException (Panic s)
123 = showString ("panic! (the `impossible' happened, GHC version "
124 ++ cProjectVersion ++ "):\n\t"
126 ++ "Please report this as a compiler bug. See:\n"
127 ++ " http://www.haskell.org/ghc/reportabug\n")
129 #if __GLASGOW_HASKELL__ < 603
130 myMkTyConApp = mkAppTy
132 myMkTyConApp = mkTyConApp
135 ghcExceptionTc = mkTyCon "GhcException"
136 {-# NOINLINE ghcExceptionTc #-}
137 instance Typeable GhcException where
138 typeOf _ = myMkTyConApp ghcExceptionTc []
144 panic, pgmError :: String -> a
145 panic x = Exception.throwDyn (Panic x)
146 pgmError x = Exception.throwDyn (ProgramError x)
148 -- #-versions because panic can't return an unboxed int, and that's
149 -- what TAG_ is with GHC at the moment. Ugh. (Simon)
150 -- No, man -- Too Beautiful! (Will)
152 panic# :: String -> FastInt
153 panic# s = case (panic s) of () -> _ILIT 0
155 assertPanic :: String -> Int -> a
156 assertPanic file line =
157 Exception.throw (Exception.AssertionFailed
158 ("ASSERT failed! file " ++ file ++ ", line " ++ show line))
162 -- | tryMost is like try, but passes through Interrupted and Panic
163 -- exceptions. Used when we want soft failures when reading interface
164 -- files, for example.
166 tryMost :: IO a -> IO (Either Exception.Exception a)
167 tryMost action = do r <- try action; filter r
169 filter (Left e@(Exception.DynException d))
170 | Just ghc_ex <- fromDynamic d
172 Interrupted -> Exception.throw e
173 Panic _ -> Exception.throw e
174 _other -> return (Left e)
178 -- | tryUser is like try, but catches only UserErrors.
179 -- These are the ones that are thrown by the TcRn monad
180 -- to signal an error in the program being compiled
181 tryUser :: IO a -> IO (Either Exception.Exception a)
182 tryUser action = tryJust tc_errors action
184 #if __GLASGOW_HASKELL__ > 504 || __GLASGOW_HASKELL__ < 500
185 tc_errors e@(Exception.IOException ioe) | isUserError ioe = Just e
186 #elif __GLASGOW_HASKELL__ == 502
187 tc_errors e@(UserError _) = Just e
189 tc_errors e@(Exception.IOException ioe) | isUserError e = Just e
191 tc_errors _other = Nothing
197 #if __GLASGOW_HASKELL__ <= 408
198 try = Exception.tryAllIO
203 #if __GLASGOW_HASKELL__ <= 408
204 catchJust = Exception.catchIO
205 tryJust = Exception.tryIO
206 ioErrors = Exception.justIoErrors
207 throwTo = Exception.raiseInThread
211 Standard signal handlers for catching ^C, which just throw an
212 exception in the target thread. The current target thread is
213 the thread at the head of the list in the MVar passed to
214 installSignalHandlers.
217 installSignalHandlers :: IO ()
218 installSignalHandlers = do
220 interrupt_exn = Exception.DynException (toDyn Interrupted)
223 withMVar interruptTargetThread $ \targets ->
226 (thread:_) -> throwTo thread interrupt_exn
228 #if !defined(mingw32_HOST_OS)
229 installHandler sigQUIT (Catch interrupt) Nothing
230 installHandler sigINT (Catch interrupt) Nothing
232 #elif __GLASGOW_HASKELL__ >= 603
233 -- GHC 6.3+ has support for console events on Windows
234 -- NOTE: running GHCi under a bash shell for some reason requires
235 -- you to press Ctrl-Break rather than Ctrl-C to provoke
236 -- an interrupt. Ctrl-C is getting blocked somewhere, I don't know
237 -- why --SDM 17/12/2004
238 let sig_handler ControlC = interrupt
239 sig_handler Break = interrupt
240 sig_handler _ = return ()
242 installHandler (Catch sig_handler)
248 {-# NOINLINE interruptTargetThread #-}
249 interruptTargetThread :: MVar [ThreadId]
250 interruptTargetThread = unsafePerformIO newEmptyMVar