#1595: duplicate "not in scope" error when giving multiple vars type-signatures at
once
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Reporter: Isaac Dupree | Owner: michalt
Type: bug | Status: closed
Priority: normal | Milestone: 7.2.1
Component: Compiler | Version: 6.6.1
Resolution: fixed | Keywords:
Operating System: Unknown/Multiple | Architecture: Unknown/Multiple
Type of failure: Incorrect | Test Case:
warning at compile-time | rename/should_fail/T1595
Blocked By: | Blocking:
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Comment (by Simon Peyton Jones ):
In [changeset:"a1dd7dd6ea276832aef0caaf805f0ab9f4e16262/ghc" a1dd7dd/ghc]:
{{{
#!CommitTicketReference repository="ghc"
revision="a1dd7dd6ea276832aef0caaf805f0ab9f4e16262"
Fallout from more assiduous RULE warnings
GHC now warns if rules compete, so that it's not predicatable
which will work and which will not. E.g.
{-# RULES
f (g x) = ...
g True = ...
#-}
If we had (f (g True)) it's not clear which rule would fire.
This showed up fraility in the libraries.
* Suppress warnigns in Control.Arrow, Control.Category for class
methods. At the moment we simply don't have a good way to write a
RULE with a class method in the LHS. See Trac #1595. Arrow and
Category attempt to do so; I have silenced the complaints with
-fno-warn-inline-rule-shadowing, but it's not a great solution.
* Adjust the NOINLINE pragma on 'GHC.Base.map' to account for the
map/coerce rule
* Adjust the rewrite rules in Enum, especially for the "literal 1"
case. See Note [Enum Integer rules for literal 1].
* Suppress warnings for 'bytestring' e.g.
libraries/bytestring/Data/ByteString.hs:895:1: warning:
Rule "ByteString specialise break (x==)" may never fire
because rule "Class op ==" for ‘==’ might fire first
Probable fix: add phase [n] or [~n] to the competing rule
}}}
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Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/1595#comment:22
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