#701: Help packages to avoid linker symbol clashes ----------------------------+----------------------------------------------- Reporter: duncan | Owner: Type: enhancement | Status: new Priority: normal | Milestone: Component: Cabal library | Version: 1.6.0.3 Severity: normal | Keywords: Difficulty: unknown | Ghcversion: Platform: | ----------------------------+----------------------------------------------- Currently it is all too easy to end up with silently clashing linker symbols. The prime example is C code linked into a Haskell package. Multiple versions of the same package will define the same linker symbols. The system linker is happy to just pick the first occurrence of a symbol (though the ghci linker is stricter). This can cause havoc if the behaviour of the C code changes from one version of the package to another (see for example the problem with mmap and darcs, ticket #700). There are a number of things we could do to improve the situation. * We could make it easier to make versioned C symbols in the C code used in a Haskell package by providing cpp macros. * We could explicitly check for unversioned C symbols in Haskell libs * We could try linking Haskell libs in such a way that the C symbols are not visible and thus cannot clash, but it would also mean they are not exported for other libs to use. -- Ticket URL: http://hackage.haskell.org/trac/hackage/ticket/701 Hackage http://haskell.org/cabal/ Hackage: Cabal and related projects