[GHC] #12151: GHC 8 allows ambiguous type without AllowAmbiguousTypes
#12151: GHC 8 allows ambiguous type without AllowAmbiguousTypes -------------------------------------+------------------------------------- Reporter: thomie | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 (Type checker) | Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Incorrect Unknown/Multiple | warning at compile-time Test Case: | Blocked By: Blocking: | Related Tickets: #7437 Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- This module compiles with GHC 8: {{{ {-# LANGUAGE DefaultSignatures #-} -- {-# LANGUAGE AllowAmbiguousTypes #-} -- Not required with GHC 8.0.1. module T12151 where class Put a where put :: a default put :: t -- This should be `a` instead of `t` put = undefined }}} GHC 7.10 required `AllowAmbiguousTypes`, to defer the ambiguity check to use sites. (Example extracted from the description of #7437) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12151> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler
#12151: GHC 8 allows ambiguous type without AllowAmbiguousTypes -------------------------------------+------------------------------------- Reporter: thomie | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler (Type | Version: 8.0.1 checker) | Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Incorrect | Unknown/Multiple warning at compile-time | Test Case: Blocked By: | Blocking: Related Tickets: #7437 | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by Simon Peyton Jones <simonpj@…>): In [changeset:"85aa6ef09346e841abf4e089b24c7f783286cd74/ghc" 85aa6ef0/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="85aa6ef09346e841abf4e089b24c7f783286cd74" Check generic-default method for ambiguity Fixes Trac #7497 and #12151. In some earlier upheaval I introduced a bug in the ambiguity check for genreric-default method. This patch fixes it. But in fixing it I realised that the sourc-location of any such error message was bogus, so I fixed that too, which involved a slightly wider change; see the comments with TcMethInfo. }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12151#comment:1> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler
#12151: GHC 8 allows ambiguous type without AllowAmbiguousTypes -------------------------------------+------------------------------------- Reporter: thomie | Owner: Type: bug | Status: merge Priority: normal | Milestone: 8.0.2 Component: Compiler (Type | Version: 8.0.1 checker) | Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: Incorrect | Test Case: warning at compile-time | typecheck/should_fail/T12151 Blocked By: | Blocking: Related Tickets: #7437 | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by simonpj): * testcase: => typecheck/should_fail/T12151 * status: new => merge * milestone: => 8.0.2 Comment: Could merge, but only if it goes easily -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12151#comment:2> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler
#12151: GHC 8 allows ambiguous type without AllowAmbiguousTypes -------------------------------------+------------------------------------- Reporter: thomie | Owner: Type: bug | Status: closed Priority: normal | Milestone: 8.0.2 Component: Compiler (Type | Version: 8.0.1 checker) | Resolution: fixed | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: Incorrect | Test Case: warning at compile-time | typecheck/should_fail/T12151 Blocked By: | Blocking: Related Tickets: #7437 | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by bgamari): * status: merge => closed * resolution: => fixed Comment: Merged as 8540c65a61e92e9c4bedb934c241e8e3eaa67047. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12151#comment:3> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler
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