#13257: out-of-range warnings for negative literals, without -XNegativeLiterals -------------------------------------+------------------------------------- Reporter: rwbarton | Owner: Type: feature | Status: new request | Priority: normal | Milestone: Component: Compiler | Version: 8.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- By default (without `NegativeLiterals`) a negated literal `-1` is desugared as `negate (fromInteger 1)`. Hence the existing out-of-range literal warning doesn't trigger for `-1 :: Word`. But we could also recognize the pattern `negate (fromInteger lit)`, and give a warning when `-lit` is out-of-range (for `Word`, this is whenever `lit` is positive). Actually this could apply to signed integer types too: if we recognized `negate (fromInteger lit)` in preference to `fromInteger lit`, we could correctly not warn about `-128 :: Int8`, even when `NegativeLiterals` is not enabled. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13257 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler