#15504: -XStrict doesn't prevent warnings from -Wunbanged-strict-patterns -------------------------------------+------------------------------------- Reporter: ChaiTRex | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.6.1 Component: Compiler | Version: 8.4.3 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: -------------------------------------+------------------------------------- I'm using: {{{ $ ghc --version The Glorious Glasgow Haskell Compilation System, version 8.4.3 }}} I was under the impression that [https://ghc.haskell.org/trac/ghc/wiki/StrictPragma#Strict -XStrict] automatically included outermost bang patterns, but either that isn't always the case or [https://downloads.haskell.org/~ghc/master/users-guide /using-warnings.html#ghc-flag--Wunbanged-strict-patterns -Wunbanged- strict-patterns] doesn't know that `-XStrict` did its job correctly: {{{#!hs {-# OPTIONS_GHC -Wunbanged-strict-patterns #-} {-# LANGUAGE BangPatterns, MagicHash, Strict, UnboxedTuples #-} module Example where import GHC.Exts (Int(I#), quotRemInt#) lastDigit :: Int -> Int lastDigit (I# x) = let (# q, r #) = quotRemInt# x 10# in I# r }}} compiles with a warning: {{{ [1 of 1] Compiling Example ( Example.hs, Example.o ) Example.hs:9:24: warning: [-Wunbanged-strict-patterns] Pattern bindings containing unlifted types should use an outermost bang pattern: (# q, r #) = quotRemInt# x 10# | 9 | lastDigit (I# x) = let (# q, r #) = quotRemInt# x 10# | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15504 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler