#13617: Segfault in Windows GHCi involving C code compiled with -O4 ----------------------------------------+------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: GHCi | Version: 8.0.2 Keywords: | Operating System: Windows Architecture: Unknown/Multiple | Type of failure: GHCi crash Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: ----------------------------------------+------------------------------- This is a very elusive bug that I noticed when running an `hmatrix` example under GHCi on Windows. Luckily, this example can be reduced down to a couple of `.hs` files and a single `.c` file (with no other Haskell or C dependencies). Unfortunately, I can't quite figure out a way to reproduce this bug without `cabal`, so I've put the source code at https://github.com/RyanGlScott/hmatrix-segfault. You can reproduce this bug by doing the following: {{{ $ git clone https://github.com/RyanGlScott/hmatrix-segfault $ git reset 2bfe38f964fca64dd776993c89ec59d35fb368a5 $ cd hmatrix-segfault/ $ cabal install $ runghc exe/Main.hs Access violation in generated code when reading ffffffffffffffff }}} Running `Main.hs` in GHCi crashes, whereas compiling it works: {{{ $ ghc exe/Main.hs $ ./exe/Main.exe [1,1,1,1,1,1,1,1,1,1,1,1] }}} I've reproduced this with GHC 7.10.3, 8.0.2, and 8.2.1-rc1. There are a couple of things that appear to be necessary to trigger the segfault: 1. You need to have `-O4` under `cc-options` in `hmatrix-segfault.cabal`. 2. You need to define the [https://github.com/RyanGlScott/hmatrix- segfault/blob/2bfe38f964fca64dd776993c89ec59d35fb368a5/src/Internal/Vectorized.hs#L38 FunCodeS] datatype. Removing either of these things causes the program to work again under GHCi. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13617 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler