#13148: Adding weak pointers to non-mutable unboxed values segfaults -------------------------------------+------------------------------------- Reporter: mboes | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 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 mboes): OK that makes sense. I was surprised that things worked with `MutVar#` because I assumed it was also unboxed, but I see now that's not the case. The types in `System.Mem.Weak` already preclude creating a weak pointer to an unboxed value. But that of `mkWeakNoFinalizer#` is not precise enough to rule that out. Is the rule that the first argument to this function is valid iff it is of unlifted (primitive) type? If so, I think it would be useful to document that there. This exploration arose from the need to retrofit a single finalizer to a codebase that makes extensive use of `Ptr` without having to switch to `ForeignPtr` everywhere. The latter being more inconvenient, since it can't appear in the type signature of foreign imports. I assume attaching a finalizer to a `Ptr` runs the risk that the finalizer might fire too early. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13148#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler