[GHC] #9756: Warn about unnecessary unsafeCoerce
#9756: Warn about unnecessary unsafeCoerce -------------------------------------+------------------------------------- Reporter: dfeuer | Owner: Type: feature request | Status: new Priority: normal | Milestone: Component: Compiler (Type | Version: 7.9 checker) | Operating System: Keywords: | Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: Difficulty: Unknown | None/Unknown Blocked By: | Test Case: Related Tickets: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- `unsafeCoerce` has been around a lot longer than `coerce`, so older code tends to use it even if `coerce` could do the job. It would be nice if the type checker could produce a warning when it detected such a situation. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9756 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#9756: Warn about unnecessary unsafeCoerce -------------------------------------+------------------------------------- Reporter: dfeuer | Owner: Type: feature | Status: new request | Milestone: Priority: normal | Version: 7.9 Component: Compiler | Keywords: (Type checker) | Architecture: Unknown/Multiple Resolution: | Difficulty: Unknown Operating System: | Blocked By: Unknown/Multiple | Related Tickets: Type of failure: | None/Unknown | Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Comment (by goldfire): I'm intrigued by this idea. But, it would surely have a performance impact, if extra analysis must be done on every use of `unsafeCoerce`. Would this be opt-in? -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9756#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#9756: Warn about unnecessary unsafeCoerce -------------------------------------+------------------------------------- Reporter: dfeuer | Owner: Type: feature | Status: new request | Milestone: Priority: normal | Version: 7.9 Component: Compiler | Keywords: (Type checker) | Architecture: Unknown/Multiple Resolution: | Difficulty: Unknown Operating System: | Blocked By: Unknown/Multiple | Related Tickets: Type of failure: | None/Unknown | Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Comment (by rwbarton): I would tend to think it should be opt-in anyways, at least for a couple compiler versions, since it would just annoy people who want to support those older compiler versions without `coerce`. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9756#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#9756: Warn about unnecessary unsafeCoerce -------------------------------------+------------------------------------- Reporter: dfeuer | Owner: Type: feature | Status: new request | Milestone: Priority: normal | Version: 7.9 Component: Compiler | Keywords: (Type checker) | Architecture: Unknown/Multiple Resolution: | Difficulty: Unknown Operating System: | Blocked By: Unknown/Multiple | Related Tickets: Type of failure: | None/Unknown | Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Comment (by simonpj): It's be a bit awkward to implement: it amounts to emitting a constraint, and then reporting a warning if the constraint ''can'' be solved, but nothing if it ''can't''. But I'm sure it's possible. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9756#comment:3 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#9756: Warn about unnecessary unsafeCoerce -------------------------------------+------------------------------------- Reporter: dfeuer | Owner: (none) Type: feature request | Status: new Priority: low | Milestone: Component: Compiler (Type | Version: 7.9 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: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by dfeuer): * priority: normal => low -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9756#comment:5 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
participants (1)
-
GHC