#5884: GHC panics while trying to derive a Generic instance for Complex a
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Reporter: mux | Owner: dreixel
Type: bug | Status: closed
Priority: normal | Milestone:
Component: Compiler | Version: 7.4.1
Resolution: fixed | Keywords:
Os: Unknown/Multiple | Architecture: Unknown/Multiple
Failure: Compile-time crash | Difficulty: Unknown
Testcase: | Blockedby:
Blocking: | Related:
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Changes (by simonpj):
* status: new => closed
* resolution: => fixed
Comment:
Fixed by
{{{
commit 9e3171c632d200ae1b259dd3501fa6f6d9ac3278
Author: Simon Peyton Jones <[email protected]>
Date: Thu Apr 26 14:39:59 2012 +0100
Make the RHS of a generic FamInst use the same type variables as the
LHS!
compiler/typecheck/TcGenGenerics.lhs | 22 ++++++++++++----------
1 files changed, 12 insertions(+), 10 deletions(-)
}}}
The problem was that in `tc_mkRepTy` you were using `dataConOrigArgTys` to
get the argument types of the data con. Now these may or may not be
identical with the `tyConTyVars` of the parent `TyCon`. (They used to be
the same, but it's a fragile assumption, and turns out not to be so here.)
The solution is simple: use `dataConInstOrigArgTys` to instantiate the
data constructor's type. That means passing a list of arg types to
`tc_mkRepTy`, which in turn may get us on the way to #5936.
Anyway this one works now.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/5884#comment:8>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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