Bodigrim pushed to branch wip/warning-for-last-and-init at Glasgow Haskell Compiler / GHC
Commits:
b85020f5 by Mike Pilgrem at 2025-08-08T23:24:01+01:00
Re CLC issue 292 Warn GHC.Internal.List.{init,last} are partial
Also corrects the warning for `tail` to refer to `Data.List.uncons` (like the existing warning for `head`).
In module `Settings.Warnings`, applies `-Wno-unrecognised-warning-flags` `-Wno-x-partial` to the `Cabal`, `filepath`, `hsc2hs`, `hpc`, `parsec`, `text` and `time` packages (outside GHC's repository).
Also bumps submodules.
- - - - -
b0bc00e3 by Andrew Lelechenko at 2025-08-08T23:28:52+01:00
Wibble
- - - - -
25 changed files:
- compiler/GHC/Core/Utils.hs
- compiler/GHC/Driver/Session/Units.hs
- compiler/GHC/Prelude/Basic.hs
- ghc/GHCi/UI.hs
- ghc/Main.hs
- hadrian/src/Settings/Warnings.hs
- libraries/Cabal
- libraries/filepath
- libraries/ghc-boot-th/GHC/Boot/TH/Ppr.hs
- libraries/ghc-internal/src/GHC/Internal/Float.hs
- libraries/ghc-internal/src/GHC/Internal/List.hs
- libraries/ghc-internal/src/GHC/Internal/System/IO.hs
- libraries/ghc-internal/src/GHC/Internal/TH/Syntax.hs
- libraries/template-haskell/vendored-filepath/System/FilePath/Posix.hs
- libraries/template-haskell/vendored-filepath/System/FilePath/Windows.hs
- testsuite/tests/driver/j-space/jspace.hs
- testsuite/tests/rts/KeepCafsBase.hs
- utils/check-exact/Transform.hs
- utils/check-exact/Utils.hs
- utils/ghc-pkg/Main.hs
- utils/ghc-toolchain/src/GHC/Toolchain/CheckArm.hs
- utils/haddock/haddock-api/src/Haddock/Backends/Xhtml.hs
- utils/haddock/haddock-library/src/Documentation/Haddock/Parser.hs
- utils/hpc
- utils/hsc2hs
Changes:
=====================================
compiler/GHC/Core/Utils.hs
=====================================
@@ -112,8 +112,7 @@ import GHC.Utils.Misc
import Data.ByteString ( ByteString )
import Data.Function ( on )
-import Data.List ( sort, sortBy, partition, zipWith4, mapAccumL )
-import qualified Data.List as Partial ( init, last )
+import Data.List ( sort, sortBy, partition, zipWith4, mapAccumL, unsnoc )
import Data.Ord ( comparing )
import Control.Monad ( guard )
import qualified Data.Set as Set
@@ -1871,10 +1870,10 @@ app_ok fun_ok primop_ok fun args
PrimOpId op _
| primOpIsDiv op
- , Lit divisor <- Partial.last args
+ , Just (initArgs, Lit divisor) <- unsnoc args
-- there can be 2 args (most div primops) or 3 args
-- (WordQuotRem2Op), hence the use of last/init
- -> not (isZeroLit divisor) && all (expr_ok fun_ok primop_ok) (Partial.init args)
+ -> not (isZeroLit divisor) && all (expr_ok fun_ok primop_ok) initArgs
-- Special case for dividing operations that fail
-- In general they are NOT ok-for-speculation
-- (which primop_ok will catch), but they ARE OK
=====================================
compiler/GHC/Driver/Session/Units.hs
=====================================
@@ -2,6 +2,8 @@
{-# LANGUAGE LambdaCase #-}
{-# LANGUAGE NondecreasingIndentation #-}
{-# LANGUAGE TupleSections #-}
+{-# OPTIONS_GHC -Wno-x-partial #-}
+
module GHC.Driver.Session.Units (initMake, initMulti) where
-- The official GHC API
=====================================
compiler/GHC/Prelude/Basic.hs
=====================================
@@ -2,8 +2,8 @@
{-# OPTIONS_HADDOCK not-home #-}
{-# OPTIONS_GHC -O2 #-} -- See Note [-O2 Prelude]
--- See Note [Proxies for head and tail]
-{-# OPTIONS_GHC -Wno-unrecognised-warning-flags -Wno-x-partial #-}
+-- See Note [Proxies for partial list functions]
+{-# OPTIONS_GHC -Wno-x-partial #-}
-- | Custom minimal GHC "Prelude"
--
@@ -24,7 +24,7 @@ module GHC.Prelude.Basic
, bit
, shiftL, shiftR
, setBit, clearBit
- , head, tail, unzip
+ , head, tail, init, last, unzip
, strictGenericLength
) where
@@ -59,7 +59,7 @@ NoImplicitPrelude. There are two motivations for this:
-}
import qualified Prelude
-import Prelude as X hiding ((<>), Applicative(..), Foldable(..), head, tail, unzip)
+import Prelude as X hiding ((<>), Applicative(..), Foldable(..), head, tail, init, last, unzip)
import Control.Applicative (Applicative(..))
import Data.Foldable as X (Foldable (elem, foldMap, foldl, foldl', foldr, length, null, product, sum))
import Data.Foldable1 as X hiding (head, last)
@@ -118,24 +118,35 @@ setBit = \ x i -> x Bits..|. bit i
clearBit :: (Num a, Bits.Bits a) => a -> Int -> a
clearBit = \ x i -> x Bits..&. Bits.complement (bit i)
-{- Note [Proxies for head and tail]
+{- Note [Proxies for partial list functions]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-Prelude.head and Prelude.tail have recently acquired {-# WARNING in "x-partial" #-},
+Prelude.head, Prelude.tail, Prelude.init and Prelude.last
+have recently acquired {-# WARNING in "x-partial" #-},
but the GHC codebase uses them fairly extensively and insists on building warning-free.
Thus, instead of adding {-# OPTIONS_GHC -Wno-x-partial #-} to every module which
employs them, we define warning-less proxies and export them from GHC.Prelude.
-}
--- See Note [Proxies for head and tail]
+-- See Note [Proxies for partial list functions]
head :: HasCallStack => [a] -> a
head = Prelude.head
{-# INLINE head #-}
--- See Note [Proxies for head and tail]
+-- See Note [Proxies for partial list functions]
tail :: HasCallStack => [a] -> [a]
tail = Prelude.tail
{-# INLINE tail #-}
+-- See Note [Proxies for partial list functions]
+init :: HasCallStack => [a] -> [a]
+init = Prelude.init
+{-# INLINE init #-}
+
+-- See Note [Proxies for partial list functions]
+last :: HasCallStack => [a] -> a
+last = Prelude.last
+{-# INLINE last #-}
+
{- |
The 'genericLength' function defined in base can't be specialised due to the
NOINLINE pragma.
=====================================
ghc/GHCi/UI.hs
=====================================
@@ -133,7 +133,7 @@ import Data.Char
import Data.Function
import qualified Data.Foldable as Foldable
import Data.IORef ( IORef, modifyIORef, newIORef, readIORef, writeIORef )
-import Data.List ( find, intercalate, intersperse,
+import Data.List ( find, intercalate, intersperse, unsnoc,
isPrefixOf, isSuffixOf, nub, partition, sort, sortBy, (\\) )
import qualified Data.List.NonEmpty as NE
import qualified Data.Set as S
@@ -2402,9 +2402,9 @@ setContextAfterLoad keep_ctxt (Just graph) = do
[] ->
let graph' = flattenSCCs $ filterToposortToModules $
GHC.topSortModuleGraph True (GHC.mkModuleGraph loaded_graph) Nothing
- in case graph' of
- [] -> setContextKeepingPackageModules keep_ctxt []
- xs -> load_this (last xs)
+ in case unsnoc graph' of
+ Nothing -> setContextKeepingPackageModules keep_ctxt []
+ Just (_, lst) -> load_this lst
(m:_) ->
load_this m
where
=====================================
ghc/Main.hs
=====================================
@@ -88,7 +88,7 @@ import System.Exit
import Control.Monad
import Control.Monad.Trans.Class
import Control.Monad.Trans.Except (throwE, runExceptT)
-import Data.List ( isPrefixOf, partition, intercalate )
+import Data.List ( isPrefixOf, partition, intercalate, unsnoc )
import Prelude
import qualified Data.List.NonEmpty as NE
@@ -115,8 +115,7 @@ main = do
argv0 <- getArgs
let (minusB_args, argv1) = partition ("-B" `isPrefixOf`) argv0
- mbMinusB | null minusB_args = Nothing
- | otherwise = Just (drop 2 (last minusB_args))
+ mbMinusB = drop 2 . snd <$> unsnoc minusB_args
let argv2 = map (mkGeneralLocated "on the commandline") argv1
=====================================
hadrian/src/Settings/Warnings.hs
=====================================
@@ -72,7 +72,10 @@ ghcWarningsArgs = do
, package terminfo ? pure [ "-Wno-unused-imports", "-Wno-deriving-typeable" ]
, package stm ? pure [ "-Wno-deriving-typeable" ]
, package osString ? pure [ "-Wno-deriving-typeable", "-Wno-unused-imports" ]
- , package parsec ? pure [ "-Wno-deriving-typeable" ]
+ , package parsec ? pure [ "-Wno-deriving-typeable"
+ , "-Wno-x-partial"
+ -- https://github.com/haskell/parsec/issues/194
+ ]
, package cabal ? pure [ "-Wno-deriving-typeable", "-Wno-incomplete-record-selectors" ]
-- The -Wno-incomplete-record-selectors is due to
@@ -80,7 +83,9 @@ ghcWarningsArgs = do
-- If that ticket is fixed, bwe can remove the flag again
, package cabalSyntax ? pure [ "-Wno-deriving-typeable" ]
- , package time ? pure [ "-Wno-deriving-typeable" ]
+ , package time ? pure [ "-Wno-deriving-typeable"
+ , "-Wno-x-partial" -- Awaiting time-1.15 release
+ ]
, package transformers ? pure [ "-Wno-unused-matches"
, "-Wno-unused-imports"
, "-Wno-redundant-constraints"
=====================================
libraries/Cabal
=====================================
@@ -1 +1 @@
-Subproject commit 703582f80f6d7f0c914ef4b885affcfc7b7b6ec8
+Subproject commit 9a343d137bcc5ae97a8d6e7a670dd4fb67ea7294
=====================================
libraries/filepath
=====================================
@@ -1 +1 @@
-Subproject commit cbcd0ccf92f47e6c10fb9cc513a7b26facfc19fe
+Subproject commit 62e71a8f512a0f2a477d8004751ccf2420b8ac28
=====================================
libraries/ghc-boot-th/GHC/Boot/TH/Ppr.hs
=====================================
@@ -13,7 +13,7 @@ import GHC.Boot.TH.PprLib
import GHC.Boot.TH.Syntax
import Data.Word ( Word8 )
import Data.Char ( toLower, chr )
-import Data.List ( intersperse )
+import Data.List ( intersperse, unsnoc )
import GHC.Show ( showMultiLineString )
import GHC.Lexeme( isVarSymChar )
import Data.Ratio ( numerator, denominator )
@@ -214,9 +214,10 @@ pprExp i (MDoE m ss_) = parensIf (i > noPrec) $
pprStms [s] = ppr s
pprStms ss = braces (semiSep ss)
-pprExp _ (CompE []) = text "<<Empty CompExp>>"
-- This will probably break with fixity declarations - would need a ';'
-pprExp _ (CompE ss) =
+pprExp _ (CompE ss) = case unsnoc ss of
+ Nothing -> text "<<Empty CompExp>>"
+ Just (ss', s) ->
if null ss'
-- If there are no statements in a list comprehension besides the last
-- one, we simply treat it like a normal list.
@@ -225,8 +226,6 @@ pprExp _ (CompE ss) =
<+> bar
<+> commaSep ss'
<> text "]"
- where s = last ss
- ss' = init ss
pprExp _ (ArithSeqE d) = ppr d
pprExp _ (ListE es) = brackets (commaSep es)
pprExp i (SigE e t) = parensIf (i > noPrec) $ pprExp sigPrec e
=====================================
libraries/ghc-internal/src/GHC/Internal/Float.hs
=====================================
@@ -13,6 +13,9 @@
{-# OPTIONS_HADDOCK not-home #-}
{-# OPTIONS_GHC -Wno-incomplete-uni-patterns #-}
+-- For init in formatRealFloatAlt
+{-# OPTIONS_GHC -Wno-x-partial #-}
+
-----------------------------------------------------------------------------
-- |
-- Module : GHC.Internal.Float
=====================================
libraries/ghc-internal/src/GHC/Internal/List.hs
=====================================
@@ -190,12 +190,18 @@ tail :: HasCallStack => [a] -> [a]
tail (_:xs) = xs
tail [] = errorEmptyList "tail"
-{-# WARNING in "x-partial" tail "This is a partial function, it throws an error on empty lists. Replace it with 'drop' 1, or use pattern matching or 'GHC.Internal.Data.List.uncons' instead. Consider refactoring to use \"Data.List.NonEmpty\"." #-}
+{-# WARNING in "x-partial" tail "This is a partial function, it throws an error on empty lists. Replace it with 'drop' 1, or use pattern matching or 'Data.List.uncons' instead. Consider refactoring to use \"Data.List.NonEmpty\"." #-}
-- | \(\mathcal{O}(n)\). Extract the last element of a list, which must be
-- finite and non-empty.
--
--- WARNING: This function is partial. Consider using 'unsnoc' instead.
+-- To disable the warning about partiality put
+-- @{-# OPTIONS_GHC -Wno-x-partial -Wno-unrecognised-warning-flags #-}@
+-- at the top of the file. To disable it throughout a package put the same
+-- options into @ghc-options@ section of Cabal file. To disable it in GHCi
+-- put @:set -Wno-x-partial -Wno-unrecognised-warning-flags@ into @~/.ghci@
+-- config file. See also the
+-- [migration guide](https://github.com/haskell/core-libraries-committee/blob/main/guides/warning...).
--
-- ==== __Examples__
--
@@ -218,10 +224,18 @@ last xs = foldl (\_ x -> x) lastError xs
lastError :: HasCallStack => a
lastError = errorEmptyList "last"
+{-# WARNING in "x-partial" last "This is a partial function, it throws an error on empty lists. Use 'Data.List.unsnoc' instead. Consider refactoring to use \"Data.List.NonEmpty\"." #-}
+
-- | \(\mathcal{O}(n)\). Return all the elements of a list except the last one.
-- The list must be non-empty.
--
--- WARNING: This function is partial. Consider using 'unsnoc' instead.
+-- To disable the warning about partiality put
+-- @{-# OPTIONS_GHC -Wno-x-partial -Wno-unrecognised-warning-flags #-}@
+-- at the top of the file. To disable it throughout a package put the same
+-- options into @ghc-options@ section of Cabal file. To disable it in GHCi
+-- put @:set -Wno-x-partial -Wno-unrecognised-warning-flags@ into @~/.ghci@
+-- config file. See also the
+-- [migration guide](https://github.com/haskell/core-libraries-committee/blob/main/guides/warning...).
--
-- ==== __Examples__
--
@@ -240,6 +254,8 @@ init (x:xs) = init' x xs
where init' _ [] = []
init' y (z:zs) = y : init' z zs
+{-# WARNING in "x-partial" init "This is a partial function, it throws an error on empty lists. Use 'Data.List.unsnoc' instead. Consider refactoring to use \"Data.List.NonEmpty\"." #-}
+
-- | \(\mathcal{O}(1)\). Test whether a list is empty.
--
-- >>> null []
=====================================
libraries/ghc-internal/src/GHC/Internal/System/IO.hs
=====================================
@@ -840,11 +840,12 @@ output_flags = std_flags
where
-- XXX bits copied from System.FilePath, since that's not available here
- combine a b
- | null b = a
- | null a = b
- | pathSeparator [last a] = a ++ b
- | otherwise = a ++ [pathSeparatorChar] ++ b
+ combine a [] = a
+ combine a b = case unsnoc a of
+ Nothing -> b
+ Just (_, lastA)
+ | pathSeparator [lastA] -> a ++ b
+ | otherwise -> a ++ [pathSeparatorChar] ++ b
tempCounter :: IORef Int
tempCounter = unsafePerformIO $ newIORef 0
=====================================
libraries/ghc-internal/src/GHC/Internal/TH/Syntax.hs
=====================================
@@ -54,6 +54,7 @@ import GHC.Internal.Base hiding (NonEmpty(..),Type, Module, sequence)
import GHC.Internal.Data.Data hiding (Fixity(..))
import GHC.Internal.Data.NonEmpty (NonEmpty(..))
import GHC.Internal.Data.Traversable
+import GHC.Internal.List (unsnoc)
import GHC.Internal.Word
import GHC.Internal.Generics (Generic)
import GHC.Internal.IORef
@@ -73,7 +74,7 @@ import GHC.Internal.Control.Monad.Fix
import GHC.Internal.Control.Exception
import GHC.Internal.Num
import GHC.Internal.IO.Unsafe
-import GHC.Internal.List (dropWhile, break, replicate, reverse, last)
+import GHC.Internal.List (dropWhile, break, replicate, reverse)
import GHC.Internal.MVar
import GHC.Internal.IO.Exception
import GHC.Internal.Unicode
@@ -82,6 +83,16 @@ import qualified GHC.Internal.Types as Kind (Type)
import GHC.Internal.ForeignSrcLang
import GHC.Internal.LanguageExtensions
+#ifdef BOOTSTRAP_TH
+#if MIN_VERSION_base(4,19,0)
+import Data.List (unsnoc)
+#else
+import Data.Maybe (maybe)
+unsnoc :: [a] -> Maybe ([a], a)
+unsnoc = foldr (\x -> Just . maybe ([], x) (\(~(a, b)) -> (x : a, b))) Nothing
+#endif
+#endif
+
-----------------------------------------------------
--
-- The Quasi class
@@ -1296,7 +1307,7 @@ mkName str
-- (i.e. non-empty, starts with capital, all alpha)
is_rev_mod_name rev_mod_str
| (compt, rest) <- break (== '.') rev_mod_str
- , not (null compt), isUpper (last compt), all is_mod_char compt
+ , Just (_, lastCompt) <- unsnoc compt, isUpper lastCompt, all is_mod_char compt
= case rest of
[] -> True
(_dot : rest') -> is_rev_mod_name rest'
=====================================
libraries/template-haskell/vendored-filepath/System/FilePath/Posix.hs
=====================================
@@ -104,7 +104,7 @@ module System.FilePath.Posix
import Data.Char(toLower, toUpper, isAsciiLower, isAsciiUpper)
import Data.Maybe(isJust)
-import Data.List(stripPrefix, isSuffixOf)
+import Data.List(stripPrefix, isSuffixOf, uncons, unsnoc)
import System.Environment(getEnv)
@@ -203,14 +203,20 @@ isExtSeparator = (== extSeparator)
splitSearchPath :: String -> [FilePath]
splitSearchPath = f
where
- f xs = case break isSearchPathSeparator xs of
- (pre, [] ) -> g pre
- (pre, _:post) -> g pre ++ f post
-
- g "" = ["." | isPosix]
- g ('\"':x@(_:_)) | isWindows && last x == '\"' = [init x]
- g x = [x]
-
+ f xs = let (pre, post) = break isSearchPathSeparator xs
+ in case uncons post of
+ Nothing -> g pre
+ Just (_, t) -> g pre ++ f t
+
+ g x = case uncons x of
+ Nothing -> ["." | isPosix]
+ Just (h, t)
+ | h == '"'
+ , Just{} <- uncons t -- >= 2
+ , isWindows
+ , Just (i, l) <- unsnoc t
+ , l == '"' -> [i]
+ | otherwise -> [x]
-- | Get a list of 'FilePath's in the $PATH variable.
getSearchPath :: IO [FilePath]
@@ -233,12 +239,17 @@ getSearchPath = fmap splitSearchPath (getEnv "PATH")
-- > splitExtension "file/path.txt.bob.fred" == ("file/path.txt.bob",".fred")
-- > splitExtension "file/path.txt/" == ("file/path.txt/","")
splitExtension :: FilePath -> (String, String)
-splitExtension x = case nameDot of
- "" -> (x,"")
- _ -> (dir ++ init nameDot, extSeparator : ext)
- where
- (dir,file) = splitFileName_ x
- (nameDot,ext) = breakEnd isExtSeparator file
+splitExtension x = case unsnoc nameDot of
+ -- Imagine x = "no-dots", then nameDot = ""
+ Nothing -> (x, mempty)
+ Just (initNameDot, _)
+ -- Imagine x = "\\shared.with.dots\no-dots"
+ | isWindows && null (dropDrive nameDot) -> (x, mempty)
+ -- Imagine x = "dir.with.dots/no-dots"
+ | any isPathSeparator ext -> (x, mempty)
+ | otherwise -> (initNameDot, extSeparator : ext)
+ where
+ (nameDot, ext) = breakEnd isExtSeparator x
-- | Get the extension of a file, returns @\"\"@ for no extension, @.ext@ otherwise.
--
@@ -594,9 +605,13 @@ replaceBaseName pth nam = combineAlways a (nam <.> ext)
-- > hasTrailingPathSeparator "test" == False
-- > hasTrailingPathSeparator "test/" == True
hasTrailingPathSeparator :: FilePath -> Bool
-hasTrailingPathSeparator "" = False
-hasTrailingPathSeparator x = isPathSeparator (last x)
+hasTrailingPathSeparator = isJust . getTrailingPathSeparator
+getTrailingPathSeparator :: FilePath -> Maybe Char
+getTrailingPathSeparator x = case unsnoc x of
+ Just (_, lastX)
+ | isPathSeparator lastX -> Just lastX
+ _ -> Nothing
hasLeadingPathSeparator :: FilePath -> Bool
hasLeadingPathSeparator "" = False
@@ -619,12 +634,12 @@ addTrailingPathSeparator x = if hasTrailingPathSeparator x then x else x ++ [pat
-- > Windows: dropTrailingPathSeparator "\\" == "\\"
-- > Posix: not (hasTrailingPathSeparator (dropTrailingPathSeparator x)) || isDrive x
dropTrailingPathSeparator :: FilePath -> FilePath
-dropTrailingPathSeparator x =
- if hasTrailingPathSeparator x && not (isDrive x)
- then let x' = dropWhileEnd isPathSeparator x
- in if null x' then [last x] else x'
- else x
-
+dropTrailingPathSeparator x = case getTrailingPathSeparator x of
+ Just lastX
+ | not (isDrive x)
+ -> let x' = dropWhileEnd isPathSeparator x
+ in if null x' then [lastX] else x'
+ _ -> x
-- | Get the directory name, move up one level.
--
@@ -863,28 +878,37 @@ makeRelative root path
-- > Posix: normalise "bob/fred/." == "bob/fred/"
-- > Posix: normalise "//home" == "/home"
normalise :: FilePath -> FilePath
-normalise path = result ++ [pathSeparator | addPathSeparator]
- where
- (drv,pth) = splitDrive path
- result = joinDrive' (normaliseDrive drv) (f pth)
+normalise filepath =
+ result <>
+ (if addPathSeparator
+ then [pathSeparator]
+ else mempty)
+ where
+ (drv,pth) = splitDrive filepath
+
+ result = joinDrive' (normaliseDrive drv) (f pth)
- joinDrive' "" "" = "."
- joinDrive' d p = joinDrive d p
+ joinDrive' d p
+ = if null d && null p
+ then "."
+ else joinDrive d p
- addPathSeparator = isDirPath pth
- && not (hasTrailingPathSeparator result)
- && not (isRelativeDrive drv)
+ addPathSeparator = isDirPath pth
+ && not (hasTrailingPathSeparator result)
+ && not (isRelativeDrive drv)
- isDirPath xs = hasTrailingPathSeparator xs
- || not (null xs) && last xs == '.' && hasTrailingPathSeparator (init xs)
+ isDirPath xs = hasTrailingPathSeparator xs || case unsnoc xs of
+ Nothing -> False
+ Just (initXs, lastXs) -> lastXs == '.' && hasTrailingPathSeparator initXs
- f = joinPath . dropDots . propSep . splitDirectories
+ f = joinPath . dropDots . propSep . splitDirectories
- propSep (x:xs) | all isPathSeparator x = [pathSeparator] : xs
- | otherwise = x : xs
- propSep [] = []
+ propSep (x:xs)
+ | all isPathSeparator x = [pathSeparator] : xs
+ | otherwise = x : xs
+ propSep [] = []
- dropDots = filter ("." /=)
+ dropDots = filter ("." /=)
normaliseDrive :: FilePath -> FilePath
normaliseDrive "" = ""
=====================================
libraries/template-haskell/vendored-filepath/System/FilePath/Windows.hs
=====================================
@@ -104,7 +104,7 @@ module System.FilePath.Windows
import Data.Char(toLower, toUpper, isAsciiLower, isAsciiUpper)
import Data.Maybe(isJust)
-import Data.List(stripPrefix, isSuffixOf)
+import Data.List(stripPrefix, isSuffixOf, uncons, unsnoc)
import System.Environment(getEnv)
@@ -203,14 +203,20 @@ isExtSeparator = (== extSeparator)
splitSearchPath :: String -> [FilePath]
splitSearchPath = f
where
- f xs = case break isSearchPathSeparator xs of
- (pre, [] ) -> g pre
- (pre, _:post) -> g pre ++ f post
-
- g "" = ["." | isPosix]
- g ('\"':x@(_:_)) | isWindows && last x == '\"' = [init x]
- g x = [x]
-
+ f xs = let (pre, post) = break isSearchPathSeparator xs
+ in case uncons post of
+ Nothing -> g pre
+ Just (_, t) -> g pre ++ f t
+
+ g x = case uncons x of
+ Nothing -> ["." | isPosix]
+ Just (h, t)
+ | h == '"'
+ , Just{} <- uncons t -- >= 2
+ , isWindows
+ , Just (i, l) <- unsnoc t
+ , l == '"' -> [i]
+ | otherwise -> [x]
-- | Get a list of 'FilePath's in the $PATH variable.
getSearchPath :: IO [FilePath]
@@ -233,12 +239,17 @@ getSearchPath = fmap splitSearchPath (getEnv "PATH")
-- > splitExtension "file/path.txt.bob.fred" == ("file/path.txt.bob",".fred")
-- > splitExtension "file/path.txt/" == ("file/path.txt/","")
splitExtension :: FilePath -> (String, String)
-splitExtension x = case nameDot of
- "" -> (x,"")
- _ -> (dir ++ init nameDot, extSeparator : ext)
- where
- (dir,file) = splitFileName_ x
- (nameDot,ext) = breakEnd isExtSeparator file
+splitExtension x = case unsnoc nameDot of
+ -- Imagine x = "no-dots", then nameDot = ""
+ Nothing -> (x, mempty)
+ Just (initNameDot, _)
+ -- Imagine x = "\\shared.with.dots\no-dots"
+ | isWindows && null (dropDrive nameDot) -> (x, mempty)
+ -- Imagine x = "dir.with.dots/no-dots"
+ | any isPathSeparator ext -> (x, mempty)
+ | otherwise -> (initNameDot, extSeparator : ext)
+ where
+ (nameDot, ext) = breakEnd isExtSeparator x
-- | Get the extension of a file, returns @\"\"@ for no extension, @.ext@ otherwise.
--
@@ -594,9 +605,13 @@ replaceBaseName pth nam = combineAlways a (nam <.> ext)
-- > hasTrailingPathSeparator "test" == False
-- > hasTrailingPathSeparator "test/" == True
hasTrailingPathSeparator :: FilePath -> Bool
-hasTrailingPathSeparator "" = False
-hasTrailingPathSeparator x = isPathSeparator (last x)
+hasTrailingPathSeparator = isJust . getTrailingPathSeparator
+getTrailingPathSeparator :: FilePath -> Maybe Char
+getTrailingPathSeparator x = case unsnoc x of
+ Just (_, lastX)
+ | isPathSeparator lastX -> Just lastX
+ _ -> Nothing
hasLeadingPathSeparator :: FilePath -> Bool
hasLeadingPathSeparator "" = False
@@ -619,12 +634,12 @@ addTrailingPathSeparator x = if hasTrailingPathSeparator x then x else x ++ [pat
-- > Windows: dropTrailingPathSeparator "\\" == "\\"
-- > Posix: not (hasTrailingPathSeparator (dropTrailingPathSeparator x)) || isDrive x
dropTrailingPathSeparator :: FilePath -> FilePath
-dropTrailingPathSeparator x =
- if hasTrailingPathSeparator x && not (isDrive x)
- then let x' = dropWhileEnd isPathSeparator x
- in if null x' then [last x] else x'
- else x
-
+dropTrailingPathSeparator x = case getTrailingPathSeparator x of
+ Just lastX
+ | not (isDrive x)
+ -> let x' = dropWhileEnd isPathSeparator x
+ in if null x' then [lastX] else x'
+ _ -> x
-- | Get the directory name, move up one level.
--
@@ -863,28 +878,37 @@ makeRelative root path
-- > Posix: normalise "bob/fred/." == "bob/fred/"
-- > Posix: normalise "//home" == "/home"
normalise :: FilePath -> FilePath
-normalise path = result ++ [pathSeparator | addPathSeparator]
- where
- (drv,pth) = splitDrive path
- result = joinDrive' (normaliseDrive drv) (f pth)
+normalise filepath =
+ result <>
+ (if addPathSeparator
+ then [pathSeparator]
+ else mempty)
+ where
+ (drv,pth) = splitDrive filepath
+
+ result = joinDrive' (normaliseDrive drv) (f pth)
- joinDrive' "" "" = "."
- joinDrive' d p = joinDrive d p
+ joinDrive' d p
+ = if null d && null p
+ then "."
+ else joinDrive d p
- addPathSeparator = isDirPath pth
- && not (hasTrailingPathSeparator result)
- && not (isRelativeDrive drv)
+ addPathSeparator = isDirPath pth
+ && not (hasTrailingPathSeparator result)
+ && not (isRelativeDrive drv)
- isDirPath xs = hasTrailingPathSeparator xs
- || not (null xs) && last xs == '.' && hasTrailingPathSeparator (init xs)
+ isDirPath xs = hasTrailingPathSeparator xs || case unsnoc xs of
+ Nothing -> False
+ Just (initXs, lastXs) -> lastXs == '.' && hasTrailingPathSeparator initXs
- f = joinPath . dropDots . propSep . splitDirectories
+ f = joinPath . dropDots . propSep . splitDirectories
- propSep (x:xs) | all isPathSeparator x = [pathSeparator] : xs
- | otherwise = x : xs
- propSep [] = []
+ propSep (x:xs)
+ | all isPathSeparator x = [pathSeparator] : xs
+ | otherwise = x : xs
+ propSep [] = []
- dropDots = filter ("." /=)
+ dropDots = filter ("." /=)
normaliseDrive :: FilePath -> FilePath
normaliseDrive "" = ""
=====================================
testsuite/tests/driver/j-space/jspace.hs
=====================================
@@ -7,7 +7,7 @@ import System.Environment
import GHC.Driver.Env.Types
import GHC.Profiling
import System.Mem
-import Data.List (isPrefixOf)
+import Data.List (isPrefixOf, unsnoc)
import Control.Monad
import System.Exit
import GHC.Platform
@@ -41,7 +41,9 @@ initGhcM xs = do
requestHeapCensus
performGC
[ys] <- filter (isPrefixOf (ghcUnitId <> ":GHC.Unit.Module.ModDetails.ModDetails")) . lines <$> readFile "jspace.hp"
- let (n :: Int) = read (last (words ys))
+ let (n :: Int) = case unsnoc (words ys) of
+ Nothing -> error "input is unexpectedly empty"
+ Just (_, lst) -> read lst
-- The output should be 50 * 8 * word_size (i.e. 3600, or 1600 on 32-bit architectures):
-- the test contains DEPTH + WIDTH + 2 = 50 modules J, H_0, .., H_DEPTH, W_1, .., W_WIDTH,
-- and each ModDetails contains 1 (info table) + 8 word-sized fields.
=====================================
testsuite/tests/rts/KeepCafsBase.hs
=====================================
@@ -1,3 +1,5 @@
+{-# OPTIONS_GHC -Wno-x-partial #-}
+
module KeepCafsBase (x) where
x :: Int
=====================================
utils/check-exact/Transform.hs
=====================================
@@ -96,6 +96,7 @@ import GHC.Data.FastString
import GHC.Types.SrcLoc
import Data.Data
+import Data.List (unsnoc)
import Data.List.NonEmpty (NonEmpty (..))
import qualified Data.List.NonEmpty as NE
import Data.Maybe
@@ -212,8 +213,9 @@ captureTypeSigSpacing (L l (SigD x (TypeSig (AnnSig (EpUniTok dca u) mp md) ns (
where
-- we want DPs for the distance from the end of the ns to the
-- AnnDColon, and to the start of the ty
- rd = case last ns of
- L (EpAnn anc' _ _) _ -> epaLocationRealSrcSpan anc'
+ rd = case unsnoc ns of
+ Nothing -> error "unexpected empty list in 'ns' variable"
+ Just (_, L (EpAnn anc' _ _) _) -> epaLocationRealSrcSpan anc'
dca' = case dca of
EpaSpan ss@(RealSrcSpan r _) -> (EpaDelta ss (ss2delta (ss2posEnd rd) r) [])
_ -> dca
@@ -294,7 +296,7 @@ setEntryDP (L (EpAnn (EpaSpan ss@(RealSrcSpan r _)) an cs) a) dp
where
cs'' = setPriorComments cs []
csd = L (EpaDelta ss dp NoComments) c:commentOrigDeltas cs'
- lc = last $ (L ca c:cs')
+ lc = NE.last (L ca c :| cs')
delta = case getLoc lc of
EpaSpan (RealSrcSpan rr _) -> ss2delta (ss2pos rr) r
EpaSpan _ -> (SameLine 0)
=====================================
utils/check-exact/Utils.hs
=====================================
@@ -37,7 +37,7 @@ import GHC.Base (NonEmpty(..))
import GHC.Parser.Lexer (allocateComments)
import Data.Data hiding ( Fixity )
-import Data.List (sortBy, partition)
+import Data.List (sortBy, partition, unsnoc)
import qualified Data.Map.Strict as Map
import Debug.Trace
@@ -734,8 +734,9 @@ ghead info [] = error $ "ghead "++info++" []"
ghead _info (h:_) = h
glast :: String -> [a] -> a
-glast info [] = error $ "glast " ++ info ++ " []"
-glast _info h = last h
+glast info xs = case unsnoc xs of
+ Nothing -> error $ "glast " ++ info ++ " []"
+ Just (_, lst) -> lst
gtail :: String -> [a] -> [a]
gtail info [] = error $ "gtail " ++ info ++ " []"
=====================================
utils/ghc-pkg/Main.hs
=====================================
@@ -8,7 +8,7 @@
{-# LANGUAGE DataKinds #-}
{-# LANGUAGE TupleSections #-}
{-# LANGUAGE ScopedTypeVariables #-}
-{-# OPTIONS_GHC -fno-warn-orphans #-}
+{-# OPTIONS_GHC -Wno-orphans -Wno-x-partial #-}
-- Fine if this comes from make/Hadrian or the pre-built base.
#include