GHC panic durring MVar operation
The following error message was displayed while loading a program into ghci by executing :r
in a ghci session:
ghc.exe: panic! (the 'impossible' happened)
(GHC version 7.8.3 for x86_64-unknown-mingw32):
thread blocked indefinitely in an MVar operation
Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug
The only edit made to the source file before compiling was the removal of an unnecessary do
on line 20 of the source file. The do
was used even though the monodic computations were written in a single line style.
I have not been able to reproduce the panic at all. The source file, unedited since the panic, now compiles without error.
The ghci session leading up to the crash is below
*Main> :t runState (filterM untouchable [1..3]) M.empty
runState (filterM untouchable [1..3]) M.empty :: ([Int], M.Map Int Int)
*Main> runState (filterM untouchable [1..3]) M.empty
([2],fromList [(1,1),(2,1),(3,1),(4,3)])
*Main> runState (filterM untouchable [1..10]) M.empty
([2,5],fromList [(1,1),(2,1),(3,1),(4,3),(5,1),(6,6),(7,1),(8,7),(9,4),(10,8),(11,1),(12,16),(13,1),(14,10),(15,9),(16,15),(17,1),(18,21),(19,1),(20,22),(21,11),(22,14),(23,1),(24,36),(25,6),(26,16),(27,13),(28,28),(29,1),(30,42),(31,1),(32,31),(33,15),(34,20),(35,13),(36,55),(37,1),(38,22),(39,17),(40,50),(41,1),(42,54),(43,1),(44,40),(45,33),(46,26),(47,1),(48,76),(49,8),(50,43),(51,21),(52,46),(53,1),(54,66),(55,17),(56,64),(57,23),(58,32),(59,1),(60,108),(61,1),(62,34),(63,41),(64,63),(65,19),(66,78),(67,1),(68,58),(69,27),(70,74),(71,1)(72,123),(73,1),(74,40),(75,49),(76,64),(77,19),(78,90),(79,1),(80,106),(81,40)])
*Main> runState (filterM untouchable [1..100]) M.empty
([2,5,52,88Interrupted.
*Main> *Main>
*Main>
*Main>
*Main>
*Main>
*Main>
*Main>
*Main> :r
[1 of 1] Compiling Main ( C:\Users\admin\Programming\Haskell\codegolf\Untouchable.hs, interpreted )
Ok, modules loaded: Main.
*Main>
ghc.exe: panic! (the 'impossible' happened)
(GHC version 7.8.3 for x86_64-unknown-mingw32):
thread blocked indefinitely in an MVar operation
Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug
Trac metadata
Trac field | Value |
---|---|
Version | 7.8.3 |
Type | Bug |
TypeOfFailure | OtherFailure |
Priority | normal |
Resolution | Unresolved |
Component | Compiler |
Test case | |
Differential revisions | |
BlockedBy | |
Related | |
Blocking | |
CC | |
Operating system | |
Architecture |