Give an explicit message when SIGSEGV happens.

Fixes haskell#767.

Signed-off-by: Edward Z. Yang <[email protected]>

cabal-install/Distribution/Client/ProjectBuilding.hs

@@ -690,7 +690,8 @@ rebuildTargets verbosity
  InstallPlan.execute jobControl keepGoing
  (BuildFailure Nothing . DependentFailed . packageId)
  installPlan $ \pkg ->
- handle (return . Left) $ fmap Right $ --TODO: review exception handling
+ --TODO: review exception handling
+ handle (\(e :: BuildFailure) -> return (Left e)) $ fmap Right $
 
  let uid = installedUnitId pkg
  Just pkgBuildStatus = Map.lookup uid pkgsBuildStatus in

cabal-install/Distribution/Client/ProjectOrchestration.hs

@@ -93,7 +93,7 @@ import Data.Either
 import Control.Exception (Exception(..))
 import System.Exit (ExitCode(..), exitFailure)
 #ifdef MIN_VERSION_unix
-import System.Posix.Signals (sigKILL)
+import System.Posix.Signals (sigKILL, sigSEGV)
 #endif
 
 
@@ -586,11 +586,14 @@ reportBuildFailures verbosity plan buildOutcomes
  | otherwise
  = False
 
+ -- NB: if the Setup script segfaulted or was interrupted,
+ -- we should give more detailed information. So only
+ -- assume that exit code 1 is "pedestrian failure."
  isFailureSelfExplanatory (BuildFailed e)
- | Just (ExitFailure _) <- fromException e = True
+ | Just (ExitFailure 1) <- fromException e = True
 
  isFailureSelfExplanatory (ConfigureFailed e)
- | Just (ExitFailure _) <- fromException e = True
+ | Just (ExitFailure 1) <- fromException e = True
 
  isFailureSelfExplanatory _ = False
 
@@ -651,7 +654,27 @@ reportBuildFailures verbosity plan buildOutcomes
  Just (ExitFailure 1) -> ""
 
 #ifdef MIN_VERSION_unix
+ -- Note [Positive "signal" exit code]
+ -- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ -- What's the business with the test for negative and positive
+ -- signal values? The API for process specifies that if the
+ -- process died due to a signal, it returns a *negative* exit
+ -- code. So that's the negative test.
+ --
+ -- What about the positive test? Well, when we find out that
+ -- a process died due to a signal, we ourselves exit with that
+ -- exit code. However, we don't "kill ourselves" with the
+ -- signal; we just exit with the same code as the signal: thus
+ -- the caller sees a *positive* exit code. So that's what
+ -- happens when we get a positive exit code.
  Just (ExitFailure n)
+ | -n == fromIntegral sigSEGV ->
+ " The build process segfaulted (i.e. SIGSEGV)."
+
+ | n == fromIntegral sigSEGV ->
+ " The build process terminated with exit code " ++ show n
+ ++ " which may be because some part of it segfaulted. (i.e. SIGSEGV)."
+
  | -n == fromIntegral sigKILL ->
  " The build process was killed (i.e. SIGKILL). " ++ explanation
 

cabal-install/tests/IntegrationTests/custom/segfault.err

@@ -0,0 +1,2 @@
+cabal: Failed to build plain-0.1.0.0. The failure occurred during the
+configure step. The build process segfaulted (i.e. SIGSEGV).

cabal-install/tests/IntegrationTests/custom/segfault.sh

@@ -0,0 +1,3 @@
+. ./common.sh
+cd segfault
+! cabal new-build

cabal-install/tests/IntegrationTests/custom/segfault/Setup.hs

@@ -0,0 +1,2 @@
+-- From http://codegolf.stackexchange.com/a/4404
+foreign import ccall main::IO()

cabal-install/tests/IntegrationTests/custom/segfault/cabal.project

@@ -0,0 +1 @@
+packages: .

cabal-install/tests/IntegrationTests/custom/segfault/plain.cabal

@@ -0,0 +1,11 @@
+name: plain
+version: 0.1.0.0
+license: BSD3
+author: Edward Z. Yang
+maintainer: [email protected]
+build-type: Custom
+cabal-version: >=1.10
+
+library
+ build-depends: base
+ default-language: Haskell2010