#15260: Xmobar crashes with segmentation fault ----------------------------------+-------------------------------------- Reporter: Voronwe | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.8.1 Component: Compiler | Version: 8.5 Resolution: | Keywords: Operating System: Linux | Architecture: x86_64 (amd64) Type of failure: Runtime crash | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | ----------------------------------+-------------------------------------- Comment (by hsyl20): I get the same kind of segfault with GHC 8.4.3 in another program unrelated to xmobar. Sadly it's not simpler as it's a standalone static program that runs directly on top of Linux in a ramdisk (using [http://haskus.org/system haskus-system])... Hence I can't use any tool like valgrind or gdb. Anyway one good thing is that it fails invariably within a few seconds and here is what I've found: 1) The segfault occurs [https://phabricator.haskell.org/diffusion/GHC/browse/ghc-8.4/rts/sm/Evac.c$6... here] because `info` is garbage (sometimes 0). 2) Recompiling with `-debug -with-rtsopts=-DS`, I get: {{{ Clock2: internal error: checkClosure (closure type 62) (GHC version 8.4.3 for x86_64_unknown_linux) Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} because of a bug [https://phabricator.haskell.org/rGHC9976bed24dda9449ac2e3e95fb4bf8b379114a28 fixed in 8.6]. After cherry-picking this commit into ghc-8.4.3, `-DS` doesn't report anything useful (nor do the other `-D*` flags). 3) Using `-V0` or `-C0` delays the segfault. 4) Same bug with GHC 8.4.2 I'll try to find the commit introducing the regression. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15260#comment:11 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler