Generate _qualified_ imports to avoid clashes with user code

.github/workflows/haskell-ci.yml

@@ -8,9 +8,9 @@
 #
 # For more information, see https://github.com/andreasabel/haskell-ci
 #
-# version: 0.17.20240127
+# version: 0.18.0.20240225
 #
-# REGENDATA ("0.17.20240127",["github","alex.cabal"])
+# REGENDATA ("0.18.0.20240225",["github","alex.cabal"])
 #
 name: Haskell-CI
 on:
@@ -32,9 +32,9 @@ jobs:
     strategy:
       matrix:
         include:
-          - compiler: ghc-9.8.1
+          - compiler: ghc-9.8.2
             compilerKind: ghc
-            compilerVersion: 9.8.1
+            compilerVersion: 9.8.2
             setup-method: ghcup
             allow-failure: false
           - compiler: ghc-9.6.4

CHANGELOG.md

@@ -1,3 +1,14 @@
+## Changes in 3.5.1.0
+
+* Drop generating output for GHC < 6.4.
+* Use qualified imports in generated code (except for `Prelude`)
+  ([Issue #258](https://github.com/haskell/alex/issues/258)).
+* Suppress warnings `tabs` and `unused-imports` for generated code
+  ([Issue #255](https://github.com/haskell/alex/issues/255)).
+* Tested with GHC 8.0 - 9.8.2.
+
+_Andreas Abel, 2024-02-29_
+
 ## Changes in 3.5.0.0
 
  * Add option `--numeric-version`.

alex.cabal

@@ -1,6 +1,6 @@
 cabal-version: >= 1.10
 name: alex
-version: 3.5.0.0
+version: 3.5.1.0
 -- don't forget updating changelog.md!
 license: BSD3
 license-file: LICENSE
@@ -22,7 +22,7 @@ category: Development
 build-type: Simple
 
 tested-with:
-        GHC == 9.8.1
+        GHC == 9.8.2
         GHC == 9.6.4
         GHC == 9.4.8
         GHC == 9.2.8

data/AlexTemplate.hs

@@ -13,8 +13,8 @@
 #  define FAST_INT Int#
 -- Do not remove this comment. Required to fix CPP parsing when using GCC and a clang-compiled alex.
 #  if __GLASGOW_HASKELL__ > 706
-#    define GTE(n,m) (tagToEnum# (n >=# m))
-#    define EQ(n,m) (tagToEnum# (n ==# m))
+#    define GTE(n,m) (GHC.Exts.tagToEnum# (n >=# m))
+#    define EQ(n,m) (GHC.Exts.tagToEnum# (n ==# m))
 #  else
 #    define GTE(n,m) (n >=# m)
 #    define EQ(n,m) (n ==# m)
@@ -40,9 +40,6 @@
 #ifdef ALEX_GHC
 data AlexAddr = AlexA# Addr#
 -- Do not remove this comment. Required to fix CPP parsing when using GCC and a clang-compiled alex.
-#if __GLASGOW_HASKELL__ < 503
-uncheckedShiftL# = shiftL#
-#endif
 
 {-# INLINE alexIndexInt16OffAddr #-}
 alexIndexInt16OffAddr :: AlexAddr -> Int# -> Int#
@@ -56,12 +53,12 @@ alexIndexInt16OffAddr (AlexA# arr) off =
         off' = off *# 2#
 #else
 #if __GLASGOW_HASKELL__ >= 901
-  int16ToInt#
+  GHC.Exts.int16ToInt#
 #endif
     (indexInt16OffAddr# arr off)
 #endif
 #else
-alexIndexInt16OffAddr arr off = arr ! off
+alexIndexInt16OffAddr = (Data.Array.!)
 #endif
 
 #ifdef ALEX_GHC
@@ -81,24 +78,19 @@ alexIndexInt32OffAddr (AlexA# arr) off =
    off' = off *# 4#
 #else
 #if __GLASGOW_HASKELL__ >= 901
-  int32ToInt#
+  GHC.Exts.int32ToInt#
 #endif
     (indexInt32OffAddr# arr off)
 #endif
 #else
-alexIndexInt32OffAddr arr off = arr ! off
+alexIndexInt32OffAddr = (Data.Array.!)
 #endif
 
 #ifdef ALEX_GHC
-
-#if __GLASGOW_HASKELL__ < 503
-quickIndex arr i = arr ! i
-#else
 -- GHC >= 503, unsafeAt is available from Data.Array.Base.
 quickIndex = unsafeAt
-#endif
 #else
-quickIndex arr i = arr ! i
+quickIndex = (Data.Array.!)
 #endif
 
 -- -----------------------------------------------------------------------------
@@ -120,26 +112,26 @@ alexScanUser user__ input__ IBOX(sc)
     case alexGetByte input__ of
       Nothing ->
 #ifdef ALEX_DEBUG
-                                   trace ("End of input.") $
+                                   Debug.Trace.trace ("End of input.") $
 #endif
                                    AlexEOF
       Just _ ->
 #ifdef ALEX_DEBUG
-                                   trace ("Error.") $
+                                   Debug.Trace.trace ("Error.") $
 #endif
                                    AlexError input__'
 
   (AlexLastSkip input__'' len, _) ->
 #ifdef ALEX_DEBUG
-    trace ("Skipping.") $
+    Debug.Trace.trace ("Skipping.") $
 #endif
     AlexSkip input__'' len
 
   (AlexLastAcc k input__''' len, _) ->
 #ifdef ALEX_DEBUG
-    trace ("Accept.") $
+    Debug.Trace.trace ("Accept.") $
 #endif
-    AlexToken input__''' len (alex_actions ! k)
+    AlexToken input__''' len ((Data.Array.!) alex_actions k)
 
 
 -- Push the input through the DFA, remembering the most recent accepting
@@ -155,7 +147,7 @@ alex_scan_tkn user__ orig_input len input__ s last_acc =
      Nothing -> (new_acc, input__)
      Just (c, new_input) ->
 #ifdef ALEX_DEBUG
-      trace ("State: " ++ show IBOX(s) ++ ", char: " ++ show c ++ " " ++ (show . chr . fromIntegral) c) $
+      Debug.Trace.trace ("State: " ++ show IBOX(s) ++ ", char: " ++ show c ++ " " ++ (show . chr . fromIntegral) c) $
 #endif
       case fromIntegral c of { IBOX(ord_c) ->
         let
@@ -226,7 +218,7 @@ alexPrevCharIs c _ input__ _ _ = c == alexInputPrevChar input__
 alexPrevCharMatches f _ input__ _ _ = f (alexInputPrevChar input__)
 
 --alexPrevCharIsOneOfPred :: Array Char Bool -> AlexAccPred _
-alexPrevCharIsOneOf arr _ input__ _ _ = arr ! alexInputPrevChar input__
+alexPrevCharIsOneOf arr _ input__ _ _ = arr Data.Array.! alexInputPrevChar input__
 
 --alexRightContext :: Int -> AlexAccPred _
 alexRightContext IBOX(sc) user__ _ _ input__ =

src/Main.hs

@@ -26,7 +26,7 @@ import Paths_alex            ( version, getDataDir )
 import Control.Exception     ( bracketOnError )
 import Control.Monad         ( when, liftM )
 import Data.Char             ( chr )
-import Data.List             ( isSuffixOf, nub )
+import Data.List             ( intercalate, isSuffixOf, nub )
 import Data.Map              ( Map )
 import Data.Version          ( showVersion )
 import System.Console.GetOpt ( getOpt, usageInfo, ArgOrder(..), OptDescr(..), ArgDescr(..) )
@@ -385,48 +385,61 @@ optNoWarnings =
     ]
 
 importsToInject :: Target -> [CLIFlags] -> String
-importsToInject _ cli = always_imports ++ debug_imports ++ glaexts_import
+importsToInject _ cli = unlines $
+  always_imports ++ debug_imports ++ glaexts_import
   where
         glaexts_import | OptGhcTarget `elem` cli    = import_glaexts
-                       | otherwise                  = ""
+                       | otherwise                  = []
 
         debug_imports  | OptDebugParser `elem` cli = import_debug
-                       | otherwise                 = ""
+                       | otherwise                 = []
 
--- CPP is turned on for -fglasogw-exts, so we can use conditional
--- compilation.  We need to #include "config.h" to get hold of
+-- We need to #include "ghcconfig.h" to get hold of
 -- WORDS_BIGENDIAN (see AlexTemplate.hs).
 
-always_imports :: String
-always_imports = "#if __GLASGOW_HASKELL__ >= 603\n" ++
-                 "#include \"ghcconfig.h\"\n" ++
-                 "#elif defined(__GLASGOW_HASKELL__)\n" ++
-                 "#include \"config.h\"\n" ++
-                 "#endif\n" ++
-                 "#if __GLASGOW_HASKELL__ >= 503\n" ++
-                 "import Data.Array\n" ++
-                 "#else\n" ++
-                 "import Array\n" ++
-                 "#endif\n"
-
-import_glaexts :: String
-import_glaexts = "#if __GLASGOW_HASKELL__ >= 503\n" ++
-                 "import Data.Array.Base (unsafeAt)\n" ++
-                 "import GHC.Exts\n" ++
-                 "#else\n" ++
-                 "import GlaExts\n" ++
-                 "#endif\n"
-
-import_debug :: String
-import_debug   = "#if __GLASGOW_HASKELL__ >= 503\n" ++
-                 "import Data.Char (chr)\n" ++
-                 "import System.IO\n" ++
-                 "import System.IO.Unsafe\n" ++
-                 "import Debug.Trace\n" ++
-                 "#else\n" ++
-                 "import IO\n" ++
-                 "import IOExts\n" ++
-                 "#endif\n"
+always_imports :: [String]
+always_imports =
+  [ "#include \"ghcconfig.h\""
+  , "import qualified Data.Array"
+  ]
+
+import_glaexts :: [String]
+import_glaexts =
+  [ "import Data.Array.Base (unsafeAt)"
+  , "import GHC.Exts (" ++ imports ++ ")"
+  , "import qualified GHC.Exts"
+  ]
+  where
+    -- We can import anything mentioning # safely,
+    -- assuming the user code does not make use of
+    -- MagicHash.
+    imports = intercalate ","
+      [ "Addr#"
+      , "Int#"
+      , "Int(I#)"
+      , "(*#)"
+      , "(+#)"
+      , "(-#)"
+      , "(==#)"
+      , "(>=#)"
+      , "indexCharOffAddr#"
+      , "indexInt16OffAddr#"
+      , "indexInt32OffAddr#"
+      , "int2Word#"
+      , "narrow16Int#"
+      , "narrow32Int#"
+      , "negateInt#"
+      , "or#"
+      , "ord#"
+      , "uncheckedShiftL#"
+      , "word2Int#"
+      ]
+
+import_debug :: [String]
+import_debug =
+  [ "import Data.Char (chr)"
+  , "import qualified Debug.Trace"
+  ]
 
 templateDir :: IO FilePath -> [CLIFlags] -> IO FilePath
 templateDir def cli

src/Output.hs

@@ -73,9 +73,9 @@ outputDFA target _ _ scheme dfa
         . str "  \"" . str (hex_chars ints) . str "\"#\n"
 
       _ ->
-          str nm . str " :: Array Int Int\n"
+          str nm . str " :: Data.Array.Array Int Int\n"
         . str nm . str " = "
-        . formatArray "listArray" upper_bound (map shows ints)
+        . formatArray "Data.Array.listArray" upper_bound (map shows ints)
         . nl
 
     outputAccept :: ShowS
@@ -84,7 +84,7 @@ outputDFA target _ _ scheme dfa
       -- see: https://github.com/simonmar/alex/issues/98
       -- str accept_nm . str " :: Array Int (AlexAcc " . str userStateTy . str ")\n"
         str accept_nm . str " = "
-      . formatArray "listArray" n_states (snd (mapAccumR outputAccs 0 accept))
+      . formatArray "Data.Array.listArray" n_states (snd (mapAccumR outputAccs 0 accept))
       . nl
 
     gscanActionType res =
@@ -95,63 +95,63 @@ outputDFA target _ _ scheme dfa
       where
         (nacts, acts) = mapAccumR outputActs 0 accept
         actionsArray :: ShowS
-        actionsArray = formatArray "array" nacts (concat acts)
+        actionsArray = formatArray "Data.Array.array" nacts (concat acts)
         body :: ShowS
         body = str actions_nm . str " = " . actionsArray . nl
         signature :: ShowS
         signature = case scheme of
           Default { defaultTypeInfo = Just (Nothing, actionty) } ->
-              str actions_nm . str " :: Array Int (" . str actionty . str ")\n"
+              str actions_nm . str " :: Data.Array.Array Int (" . str actionty . str ")\n"
           Default { defaultTypeInfo = Just (Just tyclasses, actionty) } ->
               str actions_nm . str " :: (" . str tyclasses
-            . str ") => Array Int (" . str actionty . str ")\n"
+            . str ") => Data.Array.Array Int (" . str actionty . str ")\n"
           GScan { gscanTypeInfo = Just (Nothing, toktype) } ->
-              str actions_nm . str " :: Array Int ("
+              str actions_nm . str " :: Data.Array.Array Int ("
             . gscanActionType toktype . str ")\n"
           GScan { gscanTypeInfo = Just (Just tyclasses, toktype) } ->
               str actions_nm . str " :: (" . str tyclasses
-            . str ") => Array Int ("
+            . str ") => Data.Array.Array Int ("
             . gscanActionType toktype . str ")\n"
           Basic { basicStrType = strty,
                   basicTypeInfo = Just (Nothing, toktype) } ->
-              str actions_nm . str " :: Array Int ("
+              str actions_nm . str " :: Data.Array.Array Int ("
             . str (show strty) . str " -> " . str toktype
             . str ")\n"
           Basic { basicStrType = strty,
                   basicTypeInfo = Just (Just tyclasses, toktype) } ->
               str actions_nm . str " :: (" . str tyclasses
-            . str ") => Array Int ("
+            . str ") => Data.Array.Array Int ("
             . str (show strty) . str " -> " . str toktype
             . str ")\n"
           Posn { posnStrType = strty,
                  posnTypeInfo = Just (Nothing, toktype) } ->
-              str actions_nm . str " :: Array Int (AlexPosn -> "
+              str actions_nm . str " :: Data.Array.Array Int (AlexPosn -> "
             . str (show strty) . str " -> " . str toktype
             . str ")\n"
           Posn { posnStrType = strty,
                  posnTypeInfo = Just (Just tyclasses, toktype) } ->
               str actions_nm . str " :: (" . str tyclasses
-            . str ") => Array Int (AlexPosn -> "
+            . str ") => Data.Array.Array Int (AlexPosn -> "
             . str (show strty) . str " -> " . str toktype
             . str ")\n"
           Monad { monadStrType = strty,
                   monadTypeInfo = Just (Nothing, toktype) } ->
             let
               actintty = if strty == Lazy then "Int64" else "Int"
             in
-              str actions_nm . str " :: Array Int (AlexInput -> "
+              str actions_nm . str " :: Data.Array.Array Int (AlexInput -> "
             . str actintty . str " -> Alex(" . str toktype . str "))\n"
           Monad { monadStrType = strty,
                   monadTypeInfo = Just (Just tyclasses, toktype) } ->
             let
               actintty = if strty == Lazy then "Int64" else "Int"
             in
               str actions_nm . str " :: (" . str tyclasses
-            . str ") => Array Int (AlexInput -> "
+            . str ") => Data.Array.Array Int (AlexInput -> "
             . str actintty . str " -> Alex(" . str toktype . str "))\n"
           _ ->
               -- No type signature: we don't know what the type of the actions is.
-              -- str accept_nm . str " :: Array Int (Accept Code)\n"
+              -- str accept_nm . str " :: Data.Array.Array Int (Accept Code)\n"
               id
 
 
@@ -323,7 +323,7 @@ outputDFA target _ _ scheme dfa
         = str code
 
     -- outputArr arr
-        -- = str "array " . shows (bounds arr) . space
+        -- = str "Data.Array.array " . shows (bounds arr) . space
         -- . shows (assocs arr)
 
 -- -----------------------------------------------------------------------------