internal error: stg_ap_pp_ret (with terminfo)

[judah]

When trying to run the haskeline package against HEAD, I sometimes get bus errors, segfaults or the following error:

Test: internal error: stg_ap_pp_ret
    (GHC version 6.9.20080827 for i386_apple_darwin)
    Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug
Abort trap

I've tried to strip down the relevant parts of the code. Attached is my best attempt to isolate the error. The code runs fine on 6.8.3, but crashes with a segfault or bus error if it was compiled with ghc-6.9.20080827:

$ ~/tmp/ghc-stage/bin/ghc --make -threaded Test.hs -fforce-recomp -lncurses
[1 of 1] Compiling Main             ( Test.hs, Test.o )
Linking Test ...
$ ./Test 
foobar1
Starting loop...
About to do the bad thing.
Segmentation fault

This is with OS X 10.5.4.

[judah]

I managed to strip down the test case to eliminate the dependency on the curses library. Hopefully this isolates the problem a little better. See the attached Test.hs and c_test.c.

$ ~/tmp/ghc-stage/bin/ghc --make -fforce-recomp -threaded Test.hs c_test.c
[1 of 1] Compiling Main             ( Test.hs, Test.o )
Linking Test ...

$ ./Test
Calling function.
Called function.
Calling function.
Test: internal error: stg_ap_pp_ret
    (GHC version 6.9.20080827 for i386_apple_darwin)
    Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug
Abort trap

[judah]

Test code to reproduce the error.

[judah]

C code which should be linked against Test.hs.

[igloo]

Thanks for the testcase. However, I'm unable to reproduce the problem with 6.9.20080828. I've run Test 20 or 30 times, and I just get

$ ./Test 
Calling function.
Called function.
Calling function.
Called function.

[judah]

Alternate file to reproduce the error

[judah]

It might be easier to reproduce the error with Test2.hs (attached) instead of Test.hs. Pressing ctrl-c when it prompts the user to enter a character causes a crash on my machine:

$ ./Test2 
Calling function.
Called function.
Enter a character, or press ctrl-c.
^CResult:Nothing
Calling function.
Bus error

[igloo]

After speaking to judah online, I tried with a quickest build, and my fourth attempt (with the original Test.hs) gave me:

$ ./Test 
Calling function.
Called function.
Calling function.
Test: internal error: stg_ap_pp_ret
    (GHC version 6.9.20080830 for i386_apple_darwin)
    Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug
Abort trap

[igloo]

And Test2 consistently gives me:

$ ./Test2 
Calling function.
Called function.
Enter a character, or press ctrl-c.
^CResult:Nothing
Calling function.
Test2: internal error: stg_ap_pp_ret
    (GHC version 6.9.20080830 for i386_apple_darwin)
    Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug
Abort trap

[judah]

FWIW, building HEAD with BuildFlavor=perf made the error unreproducible for me too.

[simonmar]

So you need a "quickest" build, i.e. no library optimisation?

[igloo]

quickest in the sense of mk/build.mk.sample, yes.

[simonmar]

Fixed:

Tue Sep  2 13:45:04 BST 2008  Simon Marlow <marlowsd@gmail.com>
  * FIX #2554: GHC.TopHandler.{runIO,runNonIO} should be GC roots