#11331: panic! TEST=tc198: lookupVers2 GHC.Stack.Types CallStack -------------------------------------+------------------------------------- Reporter: thomie | Owner: gridaphobe Type: bug | Status: new Priority: highest | Milestone: 8.0.1 Component: Compiler | Version: 7.11 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by gridaphobe): A couple initial observations: 1. The panic happens when ghc builds the ModIface, specifically when fingerprinting `GHC.Stack.Types.CallStack`. 2. The panic only occurs with `-O`. The module is so simple that the Core is unchanged by optimizations, but the optimized Core does include an unfolding that mentions the `CallStack` type. So, it looks like GHC is trying to fingerprint `CallStack` to write out the interface file, but fails because `GHC.Stack.Types` was never loaded. The question then is why did we not load `GHC.Stack.Types`? It's clearly imported by `GHC.Err`, the interface file confirms. But `-ddump-if-trace` doesn't mention `GHC.Stack.Types`.. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11331#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler