Include sortText in completions and improve suggestions (#2332)

* sort completions

* add an example

* Include fuzzy scores in completions sort text

* hlints

* Extend completion documentation to inform whether an identifier is alreaady imported

* Ditch alphabetical ordering - it's incompatible with qualified completions

* Fix bugs in completion help text

This fixes the ugly "Imported from 'Just B'" and other inconsistencies

* added tests for qualified completions

* Fix redundant import

* Inline Fuzzy.match to apply [1] and to be case-sensitive on first match

[1] - joom/fuzzy#4

* fixup! Fix bugs in completion help text

* Sort qualified completions first

* Filter out global suggestions that overlap with local

For example, don't suggest GHC.Exts.fromList when Data.Map.fromList is in scope alraedy

* Sort completions alphabetically

* Show provenance in detail text

* Sort local/in-scope completions first

* Fix build with GHC 9

* Ignore func symbol tests

Co-authored-by: Alex Naspo <[email protected]>
Co-authored-by: Javier Neira <[email protected]>

ghcide/src/Development/IDE/GHC/Compat/Core.hs

@@ -190,7 +190,8 @@ module Development.IDE.GHC.Compat.Core (
     SrcLoc.RealSrcSpan,
     pattern RealSrcSpan,
     SrcLoc.RealSrcLoc,
-    SrcLoc.SrcLoc(..),
+    pattern RealSrcLoc,
+    SrcLoc.SrcLoc(SrcLoc.UnhelpfulLoc),
     BufSpan,
     SrcLoc.leftmost_smallest,
     SrcLoc.containsSpan,
@@ -511,7 +512,7 @@ import           GHC.Types.TyThing.Ppr
 #else
 import           GHC.Types.Name.Set
 #endif
-import           GHC.Types.SrcLoc           (BufSpan, SrcSpan (UnhelpfulSpan))
+import           GHC.Types.SrcLoc           (BufPos, BufSpan, SrcSpan (UnhelpfulSpan), SrcLoc(UnhelpfulLoc))
 import qualified GHC.Types.SrcLoc           as SrcLoc
 import           GHC.Types.Unique.Supply
 import           GHC.Types.Var              (Var (varName), setTyVarUnique,
@@ -637,10 +638,11 @@ import           Var                        (Var (varName), setTyVarUnique,
 #if MIN_VERSION_ghc(8,10,0)
 import           Coercion                   (coercionKind)
 import           Predicate
-import           SrcLoc                     (SrcSpan (UnhelpfulSpan))
+import           SrcLoc                     (SrcSpan (UnhelpfulSpan), SrcLoc (UnhelpfulLoc))
 #else
 import           SrcLoc                     (RealLocated,
-                                             SrcSpan (UnhelpfulSpan))
+                                             SrcSpan (UnhelpfulSpan),
+                                             SrcLoc (UnhelpfulLoc))
 #endif
 #endif
 
@@ -651,6 +653,7 @@ import           System.FilePath
 
 #if !MIN_VERSION_ghc(9,0,0)
 type BufSpan = ()
+type BufPos = ()
 #endif
 
 pattern RealSrcSpan :: SrcLoc.RealSrcSpan -> Maybe BufSpan -> SrcLoc.SrcSpan
@@ -662,6 +665,15 @@ pattern RealSrcSpan x y <- ((,Nothing) -> (SrcLoc.RealSrcSpan x, y)) where
 #endif
 {-# COMPLETE RealSrcSpan, UnhelpfulSpan #-}
 
+pattern RealSrcLoc :: SrcLoc.RealSrcLoc -> Maybe BufPos-> SrcLoc.SrcLoc
+#if MIN_VERSION_ghc(9,0,0)
+pattern RealSrcLoc x y = SrcLoc.RealSrcLoc x y
+#else
+pattern RealSrcLoc x y <- ((,Nothing) -> (SrcLoc.RealSrcLoc x, y)) where
+    RealSrcLoc x _ = SrcLoc.RealSrcLoc x
+#endif
+{-# COMPLETE RealSrcLoc, UnhelpfulLoc #-}
+
 
 pattern AvailTC :: Name -> [Name] -> [FieldLabel] -> Avail.AvailInfo
 #if __GLASGOW_HASKELL__ >= 902

ghcide/src/Development/IDE/Plugin/Completions.hs

@@ -30,7 +30,6 @@ import           Development.IDE.GHC.ExactPrint               (Annotated (annsA)
 import           Development.IDE.GHC.Util                     (prettyPrint)
 import           Development.IDE.Graph
 import           Development.IDE.Graph.Classes
-import qualified Development.IDE.Types.KnownTargets           as KT
 import           Development.IDE.Plugin.CodeAction            (newImport,
                                                                newImportToEdit)
 import           Development.IDE.Plugin.CodeAction.ExactPrint
@@ -39,6 +38,7 @@ import           Development.IDE.Plugin.Completions.Types
 import           Development.IDE.Types.Exports
 import           Development.IDE.Types.HscEnvEq               (HscEnvEq (envPackageExports),
                                                                hscEnv)
+import qualified Development.IDE.Types.KnownTargets           as KT
 import           Development.IDE.Types.Location
 import           GHC.Exts                                     (fromList, toList)
 import           GHC.Generics
@@ -47,6 +47,7 @@ import           Ide.Types
 import qualified Language.LSP.Server                          as LSP
 import           Language.LSP.Types
 import qualified Language.LSP.VFS                             as VFS
+import           Text.Fuzzy.Parallel                          (Scored (..))
 
 descriptor :: PluginId -> PluginDescriptor IdeState
 descriptor plId = (defaultPluginDescriptor plId)
@@ -156,17 +157,50 @@ getCompletionsLSP ide plId
                 let clientCaps = clientCapabilities $ shakeExtras ide
                 config <- getCompletionsConfig plId
                 allCompletions <- liftIO $ getCompletions plId ideOpts cci' parsedMod bindMap pfix' clientCaps config moduleExports
-                pure $ InL (List allCompletions)
+                pure $ InL (List $ orderedCompletions allCompletions)
               _ -> return (InL $ List [])
           _ -> return (InL $ List [])
       _ -> return (InL $ List [])
 
+{- COMPLETION SORTING
+   We return an ordered set of completions (local -> nonlocal -> global).
+   Ordering is important because local/nonlocal are import aware, whereas
+   global are not and will always insert import statements, potentially redundant.
+
+   Moreover, the order prioritizes qualifiers, for instance, given:
+
+   import qualified MyModule
+   foo = MyModule.<complete>
+
+   The identifiers defined in MyModule will be listed first, followed by other
+   identifiers in importable modules.
+
+   According to the LSP specification, if no sortText is provided, the label is used
+   to sort alphabetically. Alphabetical ordering is almost never what we want,
+   so we force the LSP client to respect our ordering by using a numbered sequence.
+-}
+
+orderedCompletions :: [Scored CompletionItem] -> [CompletionItem]
+orderedCompletions [] = []
+orderedCompletions xx = zipWith addOrder [0..] xx
+    where
+    lxx = digits $ Prelude.length xx
+    digits = Prelude.length . show
+
+    addOrder :: Int -> Scored CompletionItem -> CompletionItem
+    addOrder n Scored{original = it@CompletionItem{_label,_sortText}} =
+        it{_sortText = Just $
+                T.pack(pad lxx n)
+                }
+
+    pad n x = let sx = show x in replicate (n - Prelude.length sx) '0' <> sx
+
 ----------------------------------------------------------------------------------------------------
 
 toModueNameText :: KT.Target -> T.Text
 toModueNameText target = case target of
-  KT.TargetModule m  -> T.pack $ moduleNameString m
-  _ -> T.empty
+  KT.TargetModule m -> T.pack $ moduleNameString m
+  _                 -> T.empty
 
 extendImportCommand :: PluginCommand IdeState
 extendImportCommand =