#13708: Panic! (the "impossible" happened) bug in GHC 8.2.1 rc2 -------------------------------------+------------------------------------- Reporter: deech | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.1-rc2 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- The bug can be reproduced but it does take some setup. Here's the error report in case it's familiar: {{{ ... [1 of 2] Compiling Valuators ( .stack- work/dist/x86_64-linux/Cabal-2.0.0.0/build/fltkhs-fluid-valuators/fltkhs- fluid-valuators-tmp/Valuators.hs, .stack- work/dist/x86_64-linux/Cabal-2.0.0.0/build/fltkhs-fluid-valuators/fltkhs- fluid-valuators-tmp/Valuators.o ) ghc: panic! (the 'impossible' happened) (GHC version 8.2.0.20170507 for x86_64-unknown-linux): idInfo a_ad4D Call stack: CallStack (from HasCallStack): prettyCurrentCallStack, called at compiler/utils/Outputable.hs:1134:58 in ghc:Outputable callStackDoc, called at compiler/utils/Outputable.hs:1138:37 in ghc:Outputable pprPanic, called at compiler/basicTypes/Var.hs:526:34 in ghc:Var Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} The bug is a GUI binding. Reproducing is reliable but unfortunately takes some setup. To reproduce: {{{ # Install the FLTK GUI toolkit from source.
wget http://fltk.org/pub/fltk/1.3.4/fltk-1.3.4-1-source.tar.gz tar -zxf fltk-1.3.4-1-source.tar.gz cd fltk-1.3.4-1 ./configure --enable-gl --enable-shared --enable-localjpeg --enable- localzlib --enable-localpng make sudo make install fltk-config --version 1.3.4-1
# Install the bindings from source
git clone -b 8.2.1-rc2 https://github.com/deech/fltkhs cd fltkhs cabal install
# Install the package causing the bug from source
git clone -b 8.2.1-rc2 https://github.com/deech/fltkhs-fluid-demos cd fltkhs-fluid-demos cabal install }}}
-- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13708 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler