Support explicit package names in module re-exports in .ormolu

Support explicit mention of target package name in module re-exports. Even
if the exported package is not specified as a direct dependency of the
component being formatted it will be taken into account correctly.

CHANGELOG.md

@@ -1,4 +1,4 @@
-## Unreleased
+## Ormolu 0.7.1.0
 
 * Include `base` fixity information when formatting a Haskell file that's
   not mentioned in an existing cabal file. [Issue
@@ -9,6 +9,11 @@
 
 * Ormolu is now aware of more common module re-exports by default.
 
+* Support explicit mention of target package name in module re-exports. Even
+  if the exported package is not specified as a direct dependency of the
+  component being formatted it will still be taken into account correctly.
+  [Issue 1037](https://github.com/tweag/ormolu/issues/1037).
+
 ## Ormolu 0.7.0.0
 
 * Inference of operator fixity information is now more precise and takes

README.md

@@ -200,11 +200,12 @@ Here is an example:
 
 ```haskell
 module Control.Lens exports Control.Lens.At
-module Control.Lens exports Control.Lens.Lens
+module Control.Lens exports "lens" Control.Lens.Lens
 ```
 
 Module re-export declarations can be mixed freely with fixity overrides, as
-long as each declaration is on its own line.
+long as each declaration is on its own line. As of Ormolu 0.7.1.0 explicit
+package names are allowed in re-export declarations (see the example above).
 
 Finally, all of the above-mentioned parameters can be controlled from the
 command line:

app/Main.hs

@@ -18,6 +18,7 @@ import Data.Set qualified as Set
 import Data.Text.IO qualified as TIO
 import Data.Version (showVersion)
 import Distribution.ModuleName (ModuleName)
+import Distribution.Types.PackageName (PackageName)
 import Language.Haskell.TH.Env (envQ)
 import Options.Applicative
 import Ormolu
@@ -392,7 +393,8 @@ parseFixityDeclaration :: ReadM [(OpName, FixityInfo)]
 parseFixityDeclaration = eitherReader parseFixityDeclarationStr
 
 -- | Parse a module reexport declaration.
-parseModuleReexportDeclaration :: ReadM (ModuleName, NonEmpty ModuleName)
+parseModuleReexportDeclaration ::
+  ReadM (ModuleName, NonEmpty (Maybe PackageName, ModuleName))
 parseModuleReexportDeclaration = eitherReader parseModuleReexportDeclarationStr
 
 -- | Parse 'ColorMode'.

src/Ormolu.hs

@@ -90,7 +90,7 @@ ormolu cfgWithIndices path originalInput = do
       cfg = regionIndicesToDeltas totalLines <$> cfgWithIndices
       fixityMap =
         packageFixityMap
-          (cfgDependencies cfg) -- memoized on the set of dependencies
+          (overapproximatedDependencies cfg) -- memoized on the set of dependencies
   (warnings, result0) <-
     parseModule' cfg fixityMap OrmoluParsingFailed path originalInput
   when (cfgDebug cfg) $ do

src/Ormolu/Config.hs

@@ -1,3 +1,4 @@
+{-# LANGUAGE LambdaCase #-}
 {-# LANGUAGE RecordWildCards #-}
 
 -- | Configuration options used by the tool.
@@ -8,12 +9,14 @@ module Ormolu.Config
     RegionDeltas (..),
     SourceType (..),
     defaultConfig,
+    overapproximatedDependencies,
     regionIndicesToDeltas,
     DynOption (..),
     dynOptionToLocatedStr,
   )
 where
 
+import Data.Map.Strict qualified as Map
 import Data.Set (Set)
 import Data.Set qualified as Set
 import Distribution.Types.PackageName (PackageName)
@@ -94,6 +97,21 @@ defaultConfig =
           }
     }
 
+-- | Return all dependencies of the module. This includes both the declared
+-- dependencies of the component we are working with and all potential
+-- module re-export targets.
+overapproximatedDependencies :: Config region -> Set PackageName
+overapproximatedDependencies Config {..} =
+  Set.union cfgDependencies potentialReexportTargets
+  where
+    potentialReexportTargets =
+      Set.fromList
+        . concatMap toTargetPackages
+        $ Map.elems (unModuleReexports cfgModuleReexports)
+    toTargetPackages = concatMap $ \case
+      (Nothing, _) -> []
+      (Just x, _) -> [x]
+
 -- | Convert 'RegionIndices' into 'RegionDeltas'.
 regionIndicesToDeltas ::
   -- | Total number of lines in the input

src/Ormolu/Fixity/Imports.hs

@@ -83,9 +83,9 @@ applyModuleReexports (ModuleReexports reexports) imports = imports >>= expand
       case Map.lookup (fimportModule i) reexports of
         Nothing -> pure i
         Just exports ->
-          let exportToImport mmodule =
+          let exportToImport (mpackageName, mmodule) =
                 i
-                  { fimportPackage = Nothing,
+                  { fimportPackage = mpackageName,
                     fimportModule = mmodule
                   }
            in NE.toList exports >>= expand . exportToImport

src/Ormolu/Fixity/Internal.hs

@@ -166,7 +166,7 @@ defaultFixityOverrides = FixityOverrides Map.empty
 
 -- | Module re-exports
 newtype ModuleReexports = ModuleReexports
-  { unModuleReexports :: Map ModuleName (NonEmpty ModuleName)
+  { unModuleReexports :: Map ModuleName (NonEmpty (Maybe PackageName, ModuleName))
   }
   deriving stock (Eq, Show)
 
@@ -175,7 +175,8 @@ defaultModuleReexports :: ModuleReexports
 defaultModuleReexports =
   ModuleReexports . Map.fromList $
     [ ( "Control.Lens",
-        NE.fromList
+        l
+          "lens"
           [ "Control.Lens.At",
             "Control.Lens.Cons",
             "Control.Lens.Each",
@@ -201,12 +202,14 @@ defaultModuleReexports =
           ]
       ),
       ( "Servant",
-        NE.fromList
+        l
+          "servant"
           [ "Servant.API"
           ]
       ),
       ( "Optics",
-        NE.fromList
+        l
+          "optics"
           [ "Optics.Fold",
             "Optics.Operators",
             "Optics.IxAffineFold",
@@ -216,11 +219,14 @@ defaultModuleReexports =
           ]
       ),
       ( "Test.Hspec",
-        NE.fromList
+        l
+          "hspec-expectations"
           [ "Test.Hspec.Expectations"
           ]
       )
     ]
+  where
+    l packageName xs = (Just packageName,) <$> NE.fromList xs
 
 -- | Fixity information that is specific to a package being formatted. It
 -- requires module-specific imports in order to be usable.

src/Ormolu/Fixity/Parser.hs

@@ -70,7 +70,7 @@ parseModuleReexportDeclaration ::
   -- | Parse result
   Either
     (ParseErrorBundle Text Void)
-    (ModuleName, NonEmpty ModuleName)
+    (ModuleName, NonEmpty (Maybe PackageName, ModuleName))
 parseModuleReexportDeclaration = runParser (pModuleReexport <* eof) ""
 
 pDotOrmolu :: Parser (FixityOverrides, ModuleReexports)
@@ -128,7 +128,7 @@ pOperator = OpName <$> (tickedOperator <|> normalOperator)
     normalOperator =
       takeWhile1P (Just "operator character") isOperatorConstituent
 
-pModuleReexport :: Parser (ModuleName, NonEmpty ModuleName)
+pModuleReexport :: Parser (ModuleName, NonEmpty (Maybe PackageName, ModuleName))
 pModuleReexport = do
   void (string "module")
   hidden hspace1
@@ -136,9 +136,12 @@ pModuleReexport = do
   hidden hspace1
   void (string "exports")
   hidden hspace1
+  mexportedPackage <-
+    optional $
+      between (char '\"') (char '\"') pPackageName <* hidden hspace1
   exportedModule <- pModuleName
   hidden hspace
-  return (exportingModule, NE.singleton exportedModule)
+  return (exportingModule, NE.singleton (mexportedPackage, exportedModule))
 
 pModuleName :: Parser ModuleName
 pModuleName =

src/Ormolu/Fixity/Printer.hs

@@ -1,3 +1,4 @@
+{-# LANGUAGE LambdaCase #-}
 {-# LANGUAGE OverloadedStrings #-}
 {-# LANGUAGE RecordWildCards #-}
 
@@ -20,6 +21,7 @@ import Data.Text.Lazy.Builder qualified as B
 import Data.Text.Lazy.Builder.Int qualified as B
 import Distribution.ModuleName (ModuleName)
 import Distribution.ModuleName qualified as ModuleName
+import Distribution.Types.PackageName
 import Ormolu.Fixity
 
 -- | Print out a textual representation of an @.ormolu@ file.
@@ -53,19 +55,23 @@ renderSingleFixityOverride (OpName operator, FixityInfo {..}) =
     isTickedOperator = maybe True (Char.isLetter . fst) . T.uncons
 
 renderSingleModuleReexport ::
-  (ModuleName, NonEmpty ModuleName) ->
+  (ModuleName, NonEmpty (Maybe PackageName, ModuleName)) ->
   Builder
 renderSingleModuleReexport (exportingModule, exports) =
   sconcat (renderSingle <$> exports)
   where
-    renderSingle exportedModule =
+    renderSingle (mexportedPackage, exportedModule) =
       mconcat
         [ "module ",
           renderModuleName exportingModule,
           " exports ",
+          renderOptionalPackageName mexportedPackage,
           renderModuleName exportedModule,
           "\n"
         ]
+    renderOptionalPackageName = \case
+      Nothing -> mempty
+      Just x -> "\"" <> B.fromString (unPackageName x) <> "\" "
 
 renderModuleName :: ModuleName -> Builder
 renderModuleName = B.fromString . intercalate "." . ModuleName.components

src/Ormolu/Utils/Fixity.hs

@@ -16,6 +16,7 @@ import Data.Map.Strict (Map)
 import Data.Map.Strict qualified as Map
 import Data.Text qualified as T
 import Distribution.ModuleName (ModuleName)
+import Distribution.Types.PackageName (PackageName)
 import Ormolu.Exception
 import Ormolu.Fixity
 import Ormolu.Fixity.Parser
@@ -82,6 +83,6 @@ parseModuleReexportDeclarationStr ::
   -- | Input to parse
   String ->
   -- | Parse result
-  Either String (ModuleName, NonEmpty ModuleName)
+  Either String (ModuleName, NonEmpty (Maybe PackageName, ModuleName))
 parseModuleReexportDeclarationStr =
   first errorBundlePretty . parseModuleReexportDeclaration . T.pack

tests/Ormolu/Fixity/ParserSpec.hs

@@ -78,7 +78,7 @@ spec = do
         ""
         ( T.unlines
             [ "module Control.Lens exports Control.Lens.Lens",
-              "module Control.Lens exports Control.Lens.At",
+              "module Control.Lens exports \"lens\" Control.Lens.At",
               "module Text.Megaparsec exports Control.Monad.Combinators"
             ]
         )
@@ -93,7 +93,7 @@ spec = do
               "infixl 4  <$",
               "",
               "",
-              "module Control.Lens exports Control.Lens.At",
+              "module Control.Lens exports \"lens\" Control.Lens.At",
               "infixr 9  .",
               "module Text.Megaparsec exports Control.Monad.Combinators",
               "infixl 1  >>, >>=",
@@ -170,7 +170,12 @@ spec = do
     it "parses a re-export declaration" $
       parseModuleReexportDeclaration "module Control.Lens exports Control.Lens.Lens"
         `shouldParse` ( "Control.Lens",
-                        "Control.Lens.Lens" :| []
+                        (Nothing, "Control.Lens.Lens") :| []
+                      )
+    it "parses a re-export declaration (explicit package)" $
+      parseModuleReexportDeclaration "module Control.Lens exports \"lens\" Control.Lens.Lens"
+        `shouldParse` ( "Control.Lens",
+                        (Just "lens", "Control.Lens.Lens") :| []
                       )
     it "fails with correct parse error (keyword wrong)" $
       parseModuleReexportDeclaration "foo Control.Lens exports Control.Lens.Lens"
@@ -223,10 +228,10 @@ exampleModuleReexports :: ModuleReexports
 exampleModuleReexports =
   ModuleReexports . Map.fromList $
     [ ( "Control.Lens",
-        "Control.Lens.At" :| ["Control.Lens.Lens"]
+        (Nothing, "Control.Lens.Lens") :| [(Just "lens", "Control.Lens.At")]
       ),
       ( "Text.Megaparsec",
-        "Control.Monad.Combinators" :| []
+        (Nothing, "Control.Monad.Combinators") :| []
       )
     ]
 

tests/Ormolu/FixitySpec.hs

@@ -234,7 +234,7 @@ spec = do
           ModuleReexports $
             Map.insert
               "Foo"
-              ("Control.Lens" :| [])
+              ((Nothing, "Control.Lens") :| [])
               (unModuleReexports defaultModuleReexports)
     checkFixities
       ["lens"]

tests/Ormolu/PrinterSpec.hs

@@ -50,7 +50,6 @@ checkExample srcPath' = it (fromRelFile srcPath' ++ " works") . withNiceExceptio
                 [ "base",
                   "esqueleto",
                   "hspec",
-                  "hspec-expectations",
                   "lens",
                   "servant"
                 ]