improvement: Rework IndexedContext to reuse the previously calculated scopes

compiler/src/dotty/tools/dotc/interactive/Completion.scala

@@ -48,6 +48,16 @@ case class Completion(label: String, description: String, symbols: List[Symbol])
 
 object Completion:
 
+  def scopeContext(pos: SourcePosition)(using Context): CompletionResult =
+    val tpdPath = Interactive.pathTo(ctx.compilationUnit.tpdTree, pos.span)
+    val completionContext = Interactive.contextOfPath(tpdPath).withPhase(Phases.typerPhase)
+    inContext(completionContext):
+      val untpdPath = Interactive.resolveTypedOrUntypedPath(tpdPath, pos)
+      val mode = completionMode(untpdPath, pos, forSymbolSearch = true)
+      val rawPrefix = completionPrefix(untpdPath, pos)
+      val completer = new Completer(mode, pos, untpdPath, _ => true)
+      completer.scopeCompletions
+
   /** Get possible completions from tree at `pos`
    *
    *  @return offset and list of symbols for possible completions
@@ -60,7 +70,6 @@ object Completion:
       val mode = completionMode(untpdPath, pos)
       val rawPrefix = completionPrefix(untpdPath, pos)
       val completions = rawCompletions(pos, mode, rawPrefix, tpdPath, untpdPath)
-
       postProcessCompletions(untpdPath, completions, rawPrefix)
 
   /** Get possible completions from tree at `pos`
@@ -89,7 +98,7 @@ object Completion:
    *
    * Otherwise, provide no completion suggestion.
    */
-  def completionMode(path: List[untpd.Tree], pos: SourcePosition): Mode = path match
+  def completionMode(path: List[untpd.Tree], pos: SourcePosition, forSymbolSearch: Boolean = false): Mode = path match
     // Ignore `package foo@@` and `package foo.bar@@`
     case ((_: tpd.Select) | (_: tpd.Ident)):: (_ : tpd.PackageDef) :: _  => Mode.None
     case GenericImportSelector(sel) =>
@@ -102,11 +111,14 @@ object Completion:
     case untpd.Literal(Constants.Constant(_: String)) :: _ => Mode.Term | Mode.Scope // literal completions
     case (ref: untpd.RefTree) :: _ =>
       val maybeSelectMembers = if ref.isInstanceOf[untpd.Select] then Mode.Member else Mode.Scope
-
-      if (ref.name.isTermName) Mode.Term | maybeSelectMembers
+      if (forSymbolSearch) then Mode.Term | Mode.Type | maybeSelectMembers
+      else if (ref.name.isTermName) Mode.Term | maybeSelectMembers
       else if (ref.name.isTypeName) Mode.Type | maybeSelectMembers
       else Mode.None
 
+    case (_: tpd.TypeTree | _: tpd.MemberDef) :: _ if forSymbolSearch => Mode.Type | Mode.Term
+    case (_: tpd.CaseDef) :: _ if forSymbolSearch => Mode.Type | Mode.Term
+    case Nil if forSymbolSearch =>  Mode.Type | Mode.Term
     case _ => Mode.None
 
   /** When dealing with <errors> in varios palces we check to see if they are
@@ -174,12 +186,12 @@ object Completion:
         case _ => None
 
   private object StringContextApplication:
-    def unapply(path: List[tpd.Tree]): Option[tpd.Apply] = 
+    def unapply(path: List[tpd.Tree]): Option[tpd.Apply] =
       path match
         case tpd.Select(qual @ tpd.Apply(tpd.Select(tpd.Select(_, StdNames.nme.StringContext), _), _), _) :: _ =>
           Some(qual)
         case _ => None
-      
+
 
   /** Inspect `path` to determine the offset where the completion result should be inserted. */
   def completionOffset(untpdPath: List[untpd.Tree]): Int =
@@ -230,14 +242,14 @@ object Completion:
     val result = adjustedPath match
       // Ignore synthetic select from `This` because in code it was `Ident`
       // See example in dotty.tools.languageserver.CompletionTest.syntheticThis
-      case tpd.Select(qual @ tpd.This(_), _) :: _ if qual.span.isSynthetic      => completer.scopeCompletions
+      case tpd.Select(qual @ tpd.This(_), _) :: _ if qual.span.isSynthetic      => completer.scopeCompletions.names
       case StringContextApplication(qual) =>
-        completer.scopeCompletions ++ completer.selectionCompletions(qual) 
-      case tpd.Select(qual, _) :: _               if qual.typeOpt.hasSimpleKind => 
+        completer.scopeCompletions.names ++ completer.selectionCompletions(qual)
+      case tpd.Select(qual, _) :: _               if qual.typeOpt.hasSimpleKind =>
         completer.selectionCompletions(qual)
       case tpd.Select(qual, _) :: _                                             => Map.empty
       case (tree: tpd.ImportOrExport) :: _                                      => completer.directMemberCompletions(tree.expr)
-      case _                                                                    => completer.scopeCompletions
+      case _                                                                    => completer.scopeCompletions.names
 
     interactiv.println(i"""completion info with pos    = $pos,
                           |                     term   = ${completer.mode.is(Mode.Term)},
@@ -338,6 +350,7 @@ object Completion:
          (completionMode.is(Mode.Term) && (sym.isTerm || sym.is(ModuleClass))
       || (completionMode.is(Mode.Type) && (sym.isType || sym.isStableMember)))
     )
+  end isValidCompletionSymbol
 
   given ScopeOrdering(using Context): Ordering[Seq[SingleDenotation]] with
     val order =
@@ -371,7 +384,7 @@ object Completion:
      *    (even if the import follows it syntactically)
      *  - a more deeply nested import shadowing a member or a local definition causes an ambiguity
      */
-    def scopeCompletions(using context: Context): CompletionMap =
+    def scopeCompletions(using context: Context): CompletionResult =
 
       /** Temporary data structure representing denotations with the same name introduced in a given scope
        *  as a member of a type, by a local definition or by an import clause
@@ -382,14 +395,19 @@ object Completion:
           ScopedDenotations(denots.filter(includeFn), ctx)
 
       val mappings = collection.mutable.Map.empty[Name, List[ScopedDenotations]].withDefaultValue(List.empty)
+      val renames = collection.mutable.Map.empty[Symbol, Name]
       def addMapping(name: Name, denots: ScopedDenotations) =
         mappings(name) = mappings(name) :+ denots
 
       ctx.outersIterator.foreach { case ctx @ given Context =>
         if ctx.isImportContext then
-          importedCompletions.foreach { (name, denots) =>
+          val imported = importedCompletions
+          imported.names.foreach { (name, denots) =>
             addMapping(name, ScopedDenotations(denots, ctx, include(_, name)))
           }
+          imported.renames.foreach { (name, newName) =>
+            renames(name) = newName
+          }
         else if ctx.owner.isClass then
           accessibleMembers(ctx.owner.thisType)
             .groupByName.foreach { (name, denots) =>
@@ -433,7 +451,6 @@ object Completion:
           // most deeply nested member or local definition if not shadowed by an import
           case Some(local) if local.ctx.scope == first.ctx.scope =>
             resultMappings += name -> local.denots
-
           case None if isSingleImport || isImportedInDifferentScope || isSameSymbolImportedDouble =>
             resultMappings += name -> first.denots
           case None if notConflictingWithDefaults =>
@@ -443,7 +460,7 @@ object Completion:
         }
       }
 
-      resultMappings
+      CompletionResult(resultMappings, renames.toMap)
     end scopeCompletions
 
     /** Widen only those types which are applied or are exactly nothing
@@ -485,15 +502,20 @@ object Completion:
     /** Completions introduced by imports directly in this context.
      *  Completions from outer contexts are not included.
      */
-    private def importedCompletions(using Context): CompletionMap =
+    private def importedCompletions(using Context): CompletionResult =
       val imp = ctx.importInfo
+      val renames = collection.mutable.Map.empty[Symbol, Name]
 
       if imp == null then
-        Map.empty
+        CompletionResult(Map.empty, Map.empty)
       else
         def fromImport(name: Name, nameInScope: Name): Seq[(Name, SingleDenotation)] =
           imp.site.member(name).alternatives
-            .collect { case denot if include(denot, nameInScope) => nameInScope -> denot }
+            .collect { case denot if include(denot, nameInScope) =>
+               if name != nameInScope then
+                 renames(denot.symbol) = nameInScope
+               nameInScope -> denot
+            }
 
         val givenImports = imp.importedImplicits
           .map { ref => (ref.implicitName: Name, ref.underlyingRef.denot.asSingleDenotation) }
@@ -519,7 +541,8 @@ object Completion:
               fromImport(original.toTypeName, nameInScope.toTypeName)
             }.toSeq.groupByName
 
-        givenImports ++ wildcardMembers ++ explicitMembers
+        val results = givenImports ++ wildcardMembers ++ explicitMembers
+        CompletionResult(results, renames.toMap)
     end importedCompletions
 
     /** Completions from implicit conversions including old style extensions using implicit classes */
@@ -597,7 +620,7 @@ object Completion:
 
       // 1. The extension method is visible under a simple name, by being defined or inherited or imported in a scope enclosing the reference.
       val termCompleter = new Completer(Mode.Term, pos, untpdPath, matches)
-      val extMethodsInScope = termCompleter.scopeCompletions.toList.flatMap:
+      val extMethodsInScope = termCompleter.scopeCompletions.names.toList.flatMap:
         case (name, denots) => denots.collect:
           case d: SymDenotation if d.isTerm && d.termRef.symbol.is(Extension) => (d.termRef, name.asTermName)
 
@@ -699,6 +722,7 @@ object Completion:
 
   private type CompletionMap = Map[Name, Seq[SingleDenotation]]
 
+  case class CompletionResult(names: Map[Name, Seq[SingleDenotation]], renames: Map[Symbol, Name])
   /**
    * The completion mode: defines what kinds of symbols should be included in the completion
    * results.

presentation-compiler/src/main/dotty/tools/pc/AutoImports.scala

@@ -40,7 +40,7 @@ object AutoImports:
     case class Select(qual: SymbolIdent, name: String) extends SymbolIdent:
       def value: String = s"${qual.value}.$name"
 
-    def direct(name: String): SymbolIdent = Direct(name)
+    def direct(name: String)(using Context): SymbolIdent = Direct(name)
 
     def fullIdent(symbol: Symbol)(using Context): SymbolIdent =
       val symbols = symbol.ownersIterator.toList
@@ -70,7 +70,7 @@ object AutoImports:
       importSel: Option[ImportSel]
   ):
 
-    def name: String = ident.value
+    def name(using Context): String = ident.value
 
   object SymbolImport:
 
@@ -189,10 +189,13 @@ object AutoImports:
                 ownerImport.importSel,
               )
             else
-              (
-                SymbolIdent.direct(symbol.nameBackticked),
-                Some(ImportSel.Direct(symbol)),
-              )
+              renames(symbol) match
+                case Some(rename) => (SymbolIdent.direct(rename), None)
+                case None =>
+                  (
+                    SymbolIdent.direct(symbol.nameBackticked),
+                    Some(ImportSel.Direct(symbol)),
+                  )
           end val
 
           SymbolImport(
@@ -223,9 +226,13 @@ object AutoImports:
                 importSel
               )
             case None =>
+              val reverse = symbol.ownersIterator.toList.reverse
+              val fullName = reverse.drop(1).foldLeft(SymbolIdent.direct(reverse.head.nameBackticked)){
+                case (acc, sym) => SymbolIdent.Select(acc, sym.nameBackticked(false))
+              }
               SymbolImport(
                 symbol,
-                SymbolIdent.direct(symbol.fullNameBackticked),
+                SymbolIdent.Direct(symbol.fullNameBackticked),
                 None
               )
           end match
@@ -252,7 +259,6 @@ object AutoImports:
         val topPadding =
           if importPosition.padTop then "\n"
           else ""
-
         val formatted = imports
           .map {
             case ImportSel.Direct(sym) => importName(sym)
@@ -267,15 +273,16 @@ object AutoImports:
     end renderImports
 
     private def importName(sym: Symbol): String =
-      if indexedContext.importContext.toplevelClashes(sym) then
+      if indexedContext.toplevelClashes(sym, inImportScope = true) then
         s"_root_.${sym.fullNameBackticked(false)}"
       else
         sym.ownersIterator.zipWithIndex.foldLeft((List.empty[String], false)) { case ((acc, isDone), (sym, idx)) =>
           if(isDone || sym.isEmptyPackage || sym.isRoot) (acc, true)
           else indexedContext.rename(sym) match
-            case Some(renamed) => (renamed :: acc, true)
-            case None if !sym.isPackageObject => (sym.nameBackticked(false) :: acc, false)
-            case None => (acc, false)
+            // we can't import first part
+            case Some(renamed) if idx != 0 => (renamed :: acc, true)
+            case _ if !sym.isPackageObject => (sym.nameBackticked(false) :: acc, false)
+            case _ => (acc, false)
         }._1.mkString(".")
   end AutoImportsGenerator
 

presentation-compiler/src/main/dotty/tools/pc/AutoImportsProvider.scala

@@ -44,8 +44,8 @@ final class AutoImportsProvider(
     val path =
       Interactive.pathTo(newctx.compilationUnit.tpdTree, pos.span)(using newctx)
 
-    val indexedContext = IndexedContext(
-      Interactive.contextOfPath(path)(using newctx)
+    val indexedContext = IndexedContext(pos)(
+      using Interactive.contextOfPath(path)(using newctx)
     )
     import indexedContext.ctx
 
@@ -96,7 +96,7 @@ final class AutoImportsProvider(
                 text,
                 tree,
                 unit.comments,
-                indexedContext.importContext,
+                indexedContext,
                 config
               )
             (sym: Symbol) => generator.forSymbol(sym)

presentation-compiler/src/main/dotty/tools/pc/ExtractMethodProvider.scala

@@ -51,7 +51,7 @@ final class ExtractMethodProvider(
     given locatedCtx: Context =
       val newctx = driver.currentCtx.fresh.setCompilationUnit(unit)
       Interactive.contextOfPath(path)(using newctx)
-    val indexedCtx = IndexedContext(locatedCtx)
+    val indexedCtx = IndexedContext(pos)(using locatedCtx)
     val printer =
       ShortenedTypePrinter(search, IncludeDefaultParam.Never)(using indexedCtx)
     def prettyPrint(tpe: Type) =

presentation-compiler/src/main/dotty/tools/pc/HoverProvider.scala

@@ -49,7 +49,7 @@ object HoverProvider:
     val path = unit
       .map(unit => Interactive.pathTo(unit.tpdTree, pos.span))
       .getOrElse(Interactive.pathTo(driver.openedTrees(uri), pos))
-    val indexedContext = IndexedContext(ctx)
+    val indexedContext = IndexedContext(pos)(using ctx)
 
     def typeFromPath(path: List[Tree]) =
       if path.isEmpty then NoType else path.head.typeOpt
@@ -96,7 +96,7 @@ object HoverProvider:
 
       val printerCtx = Interactive.contextOfPath(path)
       val printer = ShortenedTypePrinter(search, IncludeDefaultParam.Include)(
-        using IndexedContext(printerCtx)
+        using IndexedContext(pos)(using printerCtx)
       )
       MetalsInteractive.enclosingSymbolsWithExpressionType(
         enclosing,
@@ -134,7 +134,7 @@ object HoverProvider:
             .map(_.docstring())
             .mkString("\n")
 
-          val expresionTypeOpt = 
+          val expresionTypeOpt =
             if symbol.name == StdNames.nme.??? then
               InferExpectedType(search, driver, params).infer()
             else printer.expressionType(exprTpw)