#14430: lintUnfolding does not allow unfoldings to jump to enclosing join points -------------------------------------+------------------------------------- Reporter: nomeata | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.3 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 simonpj): The key idea is this: an unfolding is like an extra RHS for the function. So yes, this is a bug. On inspection, it's caused by `lintUnfolding` being called in the wrong place: * We want `lintUnfolding` to be called, once for all, on the unfolding (if any) of each top-level Id; that is, in the `IfaceId` case of `tc_iface_decl`. * But it isn't! Instead `lintUnfolding` is called by `tcPragExpr`, which is called from `tcUnfolding` which is called for each nested unfolding in the interface-file declaration. * This is inefficient, because the top-level call will re-lint the nested unfoldings; and it's wrong for the reason you point out. In the olden days there were no nested unfoldings in interface0-file definitions, which is why this bug got started. Might you fix, Joachim? -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14430#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler