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|
%
% (c) The University of Glasgow 2006
% (c) The GRASP Project, Glasgow University, 1992-2000
%
Defines basic funtions for printing error messages.
It's hard to put these functions anywhere else without causing
some unnecessary loops in the module dependency graph.
\begin{code}
module Panic
(
GhcException(..), showGhcException, ghcError, progName,
pgmError,
panic, panicFastInt, assertPanic, trace,
Exception.Exception(..), showException, try, tryJust, tryMost, tryUser,
catchJust, ioErrors, throwTo,
installSignalHandlers, interruptTargetThread
) where
#include "HsVersions.h"
import Config
import FastTypes
#ifndef mingw32_HOST_OS
import System.Posix.Signals
#endif /* mingw32_HOST_OS */
#if defined(mingw32_HOST_OS)
import GHC.ConsoleHandler
#endif
import Control.Exception
import Control.Concurrent ( MVar, ThreadId, withMVar, newMVar )
import Data.Dynamic
import qualified Control.Exception as Exception
import Debug.Trace ( trace )
import System.IO.Unsafe ( unsafePerformIO )
import System.IO.Error ( isUserError )
import System.Exit
import System.Environment
\end{code}
GHC's own exception type.
\begin{code}
ghcError :: GhcException -> a
ghcError e = Exception.throwDyn e
-- error messages all take the form
--
-- <location>: <error>
--
-- If the location is on the command line, or in GHC itself, then
-- <location>="ghc". All of the error types below correspond to
-- a <location> of "ghc", except for ProgramError (where the string is
-- assumed to contain a location already, so we don't print one).
data GhcException
= PhaseFailed String -- name of phase
ExitCode -- an external phase (eg. cpp) failed
| Interrupted -- someone pressed ^C
| UsageError String -- prints the short usage msg after the error
| CmdLineError String -- cmdline prob, but doesn't print usage
| Panic String -- the `impossible' happened
| InstallationError String -- an installation problem
| ProgramError String -- error in the user's code, probably
deriving Eq
progName :: String
progName = unsafePerformIO (getProgName)
{-# NOINLINE progName #-}
short_usage :: String
short_usage = "Usage: For basic information, try the `--help' option."
showException :: Exception.Exception -> String
-- Show expected dynamic exceptions specially
showException (Exception.DynException d) | Just e <- fromDynamic d
= show (e::GhcException)
showException other_exn = show other_exn
instance Show GhcException where
showsPrec _ e@(ProgramError _) = showGhcException e
showsPrec _ e@(CmdLineError _) = showString "<command line>: " . showGhcException e
showsPrec _ e = showString progName . showString ": " . showGhcException e
showGhcException :: GhcException -> String -> String
showGhcException (UsageError str)
= showString str . showChar '\n' . showString short_usage
showGhcException (PhaseFailed phase code)
= showString "phase `" . showString phase .
showString "' failed (exitcode = " . shows int_code .
showString ")"
where
int_code =
case code of
ExitSuccess -> (0::Int)
ExitFailure x -> x
showGhcException (CmdLineError str)
= showString str
showGhcException (ProgramError str)
= showString str
showGhcException (InstallationError str)
= showString str
showGhcException (Interrupted)
= showString "interrupted"
showGhcException (Panic s)
= showString ("panic! (the 'impossible' happened)\n"
++ " (GHC version " ++ cProjectVersion ++ " for " ++ TargetPlatform_NAME ++ "):\n\t"
++ s ++ "\n\n"
++ "Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug\n")
ghcExceptionTc :: TyCon
ghcExceptionTc = mkTyCon "GhcException"
{-# NOINLINE ghcExceptionTc #-}
instance Typeable GhcException where
typeOf _ = mkTyConApp ghcExceptionTc []
\end{code}
Panics and asserts.
\begin{code}
panic, pgmError :: String -> a
panic x = Exception.throwDyn (Panic x)
pgmError x = Exception.throwDyn (ProgramError x)
-- #-versions because panic can't return an unboxed int, and that's
-- what TAG_ is with GHC at the moment. Ugh. (Simon)
-- No, man -- Too Beautiful! (Will)
panicFastInt :: String -> FastInt
panicFastInt s = case (panic s) of () -> _ILIT(0)
assertPanic :: String -> Int -> a
assertPanic file line =
Exception.throw (Exception.AssertionFailed
("ASSERT failed! file " ++ file ++ ", line " ++ show line))
\end{code}
\begin{code}
-- | tryMost is like try, but passes through Interrupted and Panic
-- exceptions. Used when we want soft failures when reading interface
-- files, for example.
tryMost :: IO a -> IO (Either Exception.Exception a)
tryMost action = do r <- try action; filter r
where
filter (Left e@(Exception.DynException d))
| Just ghc_ex <- fromDynamic d
= case ghc_ex of
Interrupted -> Exception.throw e
Panic _ -> Exception.throw e
_other -> return (Left e)
filter other
= return other
-- | tryUser is like try, but catches only UserErrors.
-- These are the ones that are thrown by the TcRn monad
-- to signal an error in the program being compiled
tryUser :: IO a -> IO (Either Exception.Exception a)
tryUser action = tryJust tc_errors action
where
tc_errors e@(Exception.IOException ioe) | isUserError ioe = Just e
tc_errors _other = Nothing
\end{code}
Standard signal handlers for catching ^C, which just throw an
exception in the target thread. The current target thread is
the thread at the head of the list in the MVar passed to
installSignalHandlers.
\begin{code}
installSignalHandlers :: IO ()
installSignalHandlers = do
let
interrupt_exn = Exception.DynException (toDyn Interrupted)
interrupt = do
withMVar interruptTargetThread $ \targets ->
case targets of
[] -> return ()
(thread:_) -> throwTo thread interrupt_exn
--
#if !defined(mingw32_HOST_OS)
installHandler sigQUIT (Catch interrupt) Nothing
installHandler sigINT (Catch interrupt) Nothing
return ()
#else
-- GHC 6.3+ has support for console events on Windows
-- NOTE: running GHCi under a bash shell for some reason requires
-- you to press Ctrl-Break rather than Ctrl-C to provoke
-- an interrupt. Ctrl-C is getting blocked somewhere, I don't know
-- why --SDM 17/12/2004
let sig_handler ControlC = interrupt
sig_handler Break = interrupt
sig_handler _ = return ()
installHandler (Catch sig_handler)
return ()
#endif
{-# NOINLINE interruptTargetThread #-}
interruptTargetThread :: MVar [ThreadId]
interruptTargetThread = unsafePerformIO (newMVar [])
\end{code}
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