#13965: COMPLETE sets nerf redundant pattern-match warnings -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.1-rc2 Resolution: | Keywords: | PatternSynonyms, | PatternMatchWarnings Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by ckoparkar): * cc: mpickering (added) Comment: It looks like this was by design when the `COMPLETE` pragma was added in Phab:D2669. {{{ #!diff compiler/deSugar/Check.hs @@ -1360,8 +1455,8 @@ wrapUpTmState (residual, (_, subst)) = (residual, flattenPmVarEnv subst) dsPmWarn :: DynFlags -> DsMatchContext -> PmResult -> DsM () dsPmWarn dflags ctx@(DsMatchContext kind loc) pm_result = when (flag_i || flag_u) $ do - let exists_r = flag_i && notNull redundant - exists_i = flag_i && notNull inaccessible + let exists_r = flag_i && notNull redundant && onlyBuiltin + exists_i = flag_i && notNull inaccessible && onlyBuiltin exists_u = flag_u && notNull uncovered when exists_r $ forM_ redundant $ \(L l q) -> do putSrcSpanDs l (warnDs (Reason Opt_WarnOverlappingPatterns) @@ -1373,7 +1468,8 @@ dsPmWarn dflags ctx@(DsMatchContext kind loc) pm_result }}} Relevant comment: {{{compiler/deSugar/Check.hs}}} {{{ #!haskell data PartialResult = PartialResult { presultProvenance :: Provenance -- keep track of provenance because we don't want -- to warn about redundant matches if the result -- is contaminated with a COMPLETE pragma ...} }}} Do we want to change this? -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13965#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler