#5458: Phantom types confuse SpecConstr
---------------------------------------------+------------------------------
Reporter: simonpj | Owner:
Type: bug | Status: closed
Priority: normal | Milestone:
Component: Compiler | Version: 7.2.1
Resolution: fixed | Keywords:
Testcase: simplCore/should_compile/T5458 | Blockedby:
Difficulty: | Os: Unknown/Multiple
Blocking: | Architecture: Unknown/Multiple
Failure: None/Unknown |
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Changes (by simonpj):
* status: new => closed
* testcase: => simplCore/should_compile/T5458
* resolution: => fixed
Comment:
The main patch is this
{{{
commit e45c35fb4594668acfeeb7d9916c9b2eb03bbe22
Author: Simon Peyton Jones <[email protected]>
Date: Mon Sep 5 08:16:58 2011 +0100
De-synonym the types of the abtracted term variables in SpecConstr
This was making Text.PrettyPrint.HughesPJ give a lint-bug
when the libraries were compiled with -O2.
It's all caused by phantom type synonyms (which are, generally
speaking, a royal pain). The fix is simple, but a bit brutal.
See Note [Free type variables of the qvar types].
>---------------------------------------------------------------
compiler/specialise/SpecConstr.lhs | 22 ++++++++++++++++++++--
1 files changed, 20 insertions(+), 2 deletions(-)
}}}
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/5458#comment:2>
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The Glasgow Haskell Compiler
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