Backport "presentation-compiler: Add synthetic decorations" to LTS (#20759)

Backports #18951 to the LTS branch.

PR submitted by the release tooling.
[skip ci]

Author: WojciechMazur

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

@@ -36,6 +36,7 @@ abstract class PcCollector[T](
   val uri = params.uri().nn
   val filePath = Paths.get(uri).nn
   val sourceText = params.text().nn
+  val text = sourceText.toCharArray().nn
   val source =
     SourceFile.virtual(filePath.toString(), sourceText)
   driver.run(uri, source)
@@ -70,45 +71,6 @@ abstract class PcCollector[T](
       parent: Option[Tree]
   )(tree: Tree| EndMarker, pos: SourcePosition, symbol: Option[Symbol]): T
 
-  /**
-   * @return (adjusted position, should strip backticks)
-   */
-  def adjust(
-      pos1: SourcePosition,
-      forRename: Boolean = false
-  ): (SourcePosition, Boolean) =
-    if !pos1.span.isCorrect then (pos1, false)
-    else
-      val pos0 =
-        val span = pos1.span
-        if span.exists && span.point > span.end then
-          pos1.withSpan(
-            span
-              .withStart(span.point)
-              .withEnd(span.point + (span.end - span.start))
-          )
-        else pos1
-
-      val pos =
-        if pos0.end > 0 && sourceText(pos0.end - 1) == ',' then
-          pos0.withEnd(pos0.end - 1)
-        else pos0
-      val isBackticked =
-        sourceText(pos.start) == '`' &&
-          pos.end > 0 &&
-          sourceText(pos.end - 1) == '`'
-      // when the old name contains backticks, the position is incorrect
-      val isOldNameBackticked = sourceText(pos.start) != '`' &&
-        pos.start > 0 &&
-        sourceText(pos.start - 1) == '`' &&
-        sourceText(pos.end) == '`'
-      if isBackticked && forRename then
-        (pos.withStart(pos.start + 1).withEnd(pos.end - 1), true)
-      else if isOldNameBackticked then
-        (pos.withStart(pos.start - 1).withEnd(pos.end + 1), false)
-      else (pos, false)
-  end adjust
-
   def symbolAlternatives(sym: Symbol) =
     def member(parent: Symbol) = parent.info.member(sym.name).symbol
     def primaryConstructorTypeParam(owner: Symbol) =
@@ -447,7 +409,7 @@ abstract class PcCollector[T](
          */
         case sel: Select
           if sel.span.isCorrect && filter(sel) &&
-            !isForComprehensionMethod(sel) =>
+            !sel.isForComprehensionMethod =>
           occurrences + collect(
             sel,
             pos.withSpan(selectNameSpan(sel))
@@ -602,17 +564,6 @@ abstract class PcCollector[T](
         Span(span.start, span.start + realName.length, point)
       else Span(point, span.end, point)
     else span
-
-  private val forCompMethods =
-    Set(nme.map, nme.flatMap, nme.withFilter, nme.foreach)
-
-  // We don't want to collect synthethic `map`, `withFilter`, `foreach` and `flatMap` in for-comprenhensions
-  private def isForComprehensionMethod(sel: Select): Boolean =
-    val syntheticName = sel.name match
-      case name: TermName => forCompMethods(name)
-      case _ => false
-    val wrongSpan = sel.qualifier.span.contains(sel.nameSpan)
-    syntheticName && wrongSpan
 end PcCollector
 
 object PcCollector:

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

@@ -23,7 +23,7 @@ final class PcDocumentHighlightProvider(
       toAdjust: SourcePosition,
       sym: Option[Symbol]
   ): DocumentHighlight =
-    val (pos, _) = adjust(toAdjust)
+    val (pos, _) = toAdjust.adjust(text)
     tree match
       case _: NamedDefTree =>
         DocumentHighlight(pos.toLsp, DocumentHighlightKind.Write)

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

@@ -27,8 +27,6 @@ final class PcInlineValueProviderImpl(
 ) extends PcCollector[Option[Occurence]](driver, params)
     with InlineValueProvider:
 
-  val text = params.text().nn.toCharArray().nn
-
   val position: l.Position = pos.toLsp.getStart().nn
 
   override def collect(parent: Option[Tree])(
@@ -38,7 +36,7 @@ final class PcInlineValueProviderImpl(
   ): Option[Occurence] =
     tree match
       case tree: Tree =>
-        val (adjustedPos, _) = adjust(pos)
+        val (adjustedPos, _) = pos.adjust(text)
         Some(Occurence(tree, parent, adjustedPos))
       case _ => None
 

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

@@ -35,7 +35,7 @@ final class PcRenameProvider(
   def collect(
       parent: Option[Tree]
   )(tree: Tree | EndMarker, toAdjust: SourcePosition, sym: Option[Symbol]): l.TextEdit =
-    val (pos, stripBackticks) = adjust(toAdjust, forRename = true)
+    val (pos, stripBackticks) = toAdjust.adjust(text, forRename = true)
     l.TextEdit(
       pos.toLsp,
       if stripBackticks then newName.stripBackticks else newName

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

@@ -74,7 +74,7 @@ final class PcSemanticTokensProvider(
         Some(
           makeNode(
             sym = sym,
-            pos = adjust(pos)._1,
+            pos = pos.adjust(text)._1,
             isDefinition = isDefinition(tree),
             isDeclaration = isDeclaration(tree)
           )

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

@@ -0,0 +1,266 @@
+package dotty.tools.pc
+
+
+import java.nio.file.Paths
+
+import scala.meta.internal.metals.ReportContext
+import dotty.tools.pc.utils.MtagsEnrichments.*
+import dotty.tools.pc.printer.ShortenedTypePrinter
+import scala.meta.pc.SymbolSearch
+import scala.meta.pc.SyntheticDecoration
+import scala.meta.pc.SyntheticDecorationsParams
+import scala.meta.internal.pc.DecorationKind
+import scala.meta.internal.pc.Decoration
+
+
+import dotty.tools.dotc.ast.tpd
+import dotty.tools.dotc.ast.tpd.*
+import dotty.tools.dotc.core.Contexts.Context
+import dotty.tools.dotc.core.Flags
+import dotty.tools.dotc.core.StdNames.*
+import dotty.tools.dotc.core.Types.*
+import dotty.tools.dotc.interactive.Interactive
+import dotty.tools.dotc.interactive.InteractiveDriver
+import dotty.tools.dotc.util.SourceFile
+import dotty.tools.dotc.util.SourcePosition
+import dotty.tools.dotc.util.Spans.Span
+import dotty.tools.pc.IndexedContext
+
+final class PcSyntheticDecorationsProvider(
+    driver: InteractiveDriver,
+    params: SyntheticDecorationsParams,
+    symbolSearch: SymbolSearch,
+)(using ReportContext):
+
+  val uri = params.uri().nn
+  val filePath = Paths.get(uri).nn
+  val sourceText = params.text().nn
+  val text = sourceText.toCharArray().nn
+  val source =
+    SourceFile.virtual(filePath.toString, sourceText)
+  driver.run(uri, source)
+  given ctx: Context = driver.currentCtx
+  val unit = driver.currentCtx.run.nn.units.head
+
+  def tpdTree = unit.tpdTree
+
+  def provide(): List[SyntheticDecoration] =
+    val deepFolder = DeepFolder[Synthetics](collectDecorations)
+    deepFolder(Synthetics.empty, tpdTree).decorations
+
+  def collectDecorations(
+      decorations: Synthetics,
+      tree: Tree,
+  ): Synthetics =
+    tree match
+      case ImplicitConversion(name, range) if params.implicitConversions() =>
+        val adjusted = range.adjust(text)._1
+        decorations
+          .add(
+            Decoration(
+              adjusted.startPos.toLsp,
+              name + "(",
+              DecorationKind.ImplicitConversion,
+            )
+          )
+          .add(
+            Decoration(
+              adjusted.endPos.toLsp,
+              ")",
+              DecorationKind.ImplicitConversion,
+            )
+          )
+      case ImplicitParameters(names, pos, allImplicit)
+          if params.implicitParameters() =>
+        val label =
+          if allImplicit then names.mkString("(", ", ", ")")
+          else names.mkString(", ", ", ", "")
+        decorations.add(
+          Decoration(
+            pos.adjust(text)._1.toLsp,
+            label,
+            DecorationKind.ImplicitParameter,
+          )
+        )
+      case TypeParameters(tpes, pos, sel)
+          if params.typeParameters() && !syntheticTupleApply(sel) =>
+        val label = tpes.map(toLabel(_, pos)).mkString("[", ", ", "]")
+        decorations.add(
+          Decoration(
+            pos.adjust(text)._1.endPos.toLsp,
+            label,
+            DecorationKind.TypeParameter,
+          )
+        )
+      case InferredType(tpe, pos, defTree) if params.inferredTypes() =>
+        val adjustedPos = pos.adjust(text)._1.endPos
+        if decorations.containsDef(adjustedPos.start) then decorations
+        else
+          decorations.add(
+            Decoration(
+              adjustedPos.toLsp,
+              ": " + toLabel(tpe, pos),
+              DecorationKind.InferredType,
+            ),
+            adjustedPos.start,
+          )
+      case _ => decorations
+
+  private def toLabel(
+      tpe: Type,
+      pos: SourcePosition,
+  ): String =
+    val tpdPath =
+      Interactive.pathTo(unit.tpdTree, pos.span)
+    
+    val indexedCtx = IndexedContext(Interactive.contextOfPath(tpdPath))
+    val printer = ShortenedTypePrinter(
+      symbolSearch
+    )(using indexedCtx)
+    def optDealias(tpe: Type): Type =
+      def isInScope(tpe: Type): Boolean =
+        tpe match
+          case tref: TypeRef =>
+            indexedCtx.lookupSym(
+              tref.currentSymbol
+            ) == IndexedContext.Result.InScope
+          case AppliedType(tycon, args) =>
+            isInScope(tycon) && args.forall(isInScope)
+          case _ => true
+      if isInScope(tpe)
+      then tpe
+      else tpe.metalsDealias(using indexedCtx.ctx)
+
+    val dealiased = optDealias(tpe)
+    printer.tpe(dealiased)
+  end toLabel
+
+  private val definitions = IndexedContext(ctx).ctx.definitions
+  private def syntheticTupleApply(tree: Tree): Boolean =
+    tree match
+      case sel: Select =>
+        if definitions.isTupleNType(sel.symbol.info.finalResultType) then
+          sel match
+            case Select(tupleClass: Ident, _)
+                if !tupleClass.span.isZeroExtent &&
+                  tupleClass.span.exists &&
+                  tupleClass.name.startsWith("Tuple") =>
+              val pos = tupleClass.sourcePos
+              !sourceText.slice(pos.start, pos.end).mkString.startsWith("Tuple")
+            case _ => true
+        else false
+      case _ => false
+end PcSyntheticDecorationsProvider
+
+object ImplicitConversion:
+  def unapply(tree: Tree)(using Context) =
+    tree match
+      case Apply(fun: Ident, args) if isSynthetic(fun) =>
+        implicitConversion(fun, args)
+      case Apply(Select(fun, name), args)
+          if name == nme.apply && isSynthetic(fun) =>
+        implicitConversion(fun, args)
+      case _ => None
+  private def isSynthetic(tree: Tree)(using Context) =
+    tree.span.isSynthetic && tree.symbol.isOneOf(Flags.GivenOrImplicit)
+
+  private def implicitConversion(fun: Tree, args: List[Tree])(using Context) =
+    val lastArgPos =
+      args.lastOption.map(_.sourcePos).getOrElse(fun.sourcePos)
+    Some(
+      fun.symbol.decodedName,
+      lastArgPos.withStart(fun.sourcePos.start),
+    )
+end ImplicitConversion
+
+object ImplicitParameters:
+  def unapply(tree: Tree)(using Context) =
+    tree match
+      case Apply(fun, args)
+          if args.exists(isSyntheticArg) && !tree.sourcePos.span.isZeroExtent =>
+        val (implicitArgs, providedArgs) = args.partition(isSyntheticArg)
+        val allImplicit = providedArgs.isEmpty
+        val pos = implicitArgs.head.sourcePos
+        Some(implicitArgs.map(_.symbol.decodedName), pos, allImplicit)
+      case Apply(ta @ TypeApply(fun, _), _)
+          if fun.span.isSynthetic && isValueOf(fun) =>
+        Some(
+          List("new " + tpnme.valueOf.decoded.capitalize + "(...)"),
+          fun.sourcePos,
+          true,
+        )
+      case _ => None
+  private def isValueOf(tree: Tree)(using Context) =
+    val symbol = tree.symbol.maybeOwner
+    symbol.name.decoded == tpnme.valueOf.decoded.capitalize
+  private def isSyntheticArg(tree: Tree)(using Context) = tree match
+    case tree: Ident =>
+      tree.span.isSynthetic && tree.symbol.isOneOf(Flags.GivenOrImplicit)
+    case _ => false
+end ImplicitParameters
+
+object TypeParameters:
+  def unapply(tree: Tree)(using Context) =
+    tree match
+      case TypeApply(sel: Select, _) if sel.isForComprehensionMethod => None
+      case TypeApply(fun, args) if inferredTypeArgs(args) =>
+        val pos = fun match
+          case sel: Select if sel.isInfix =>
+            sel.sourcePos.withEnd(sel.nameSpan.end)
+          case _ => fun.sourcePos
+        val tpes = args.map(_.tpe.stripTypeVar.widen.finalResultType)
+        Some((tpes, pos.endPos, fun))
+      case _ => None
+  private def inferredTypeArgs(args: List[Tree]): Boolean =
+    args.forall {
+      case tt: TypeTree if tt.span.exists && !tt.span.isZeroExtent => true
+      case _ => false
+    }
+end TypeParameters
+
+object InferredType:
+  def unapply(tree: Tree)(using Context) =
+    tree match
+      case vd @ ValDef(_, tpe, _)
+          if isValidSpan(tpe.span, vd.nameSpan) &&
+            !vd.symbol.is(Flags.Enum) =>
+        if vd.symbol == vd.symbol.sourceSymbol then
+          Some(tpe.tpe, tpe.sourcePos.withSpan(vd.nameSpan), vd)
+        else None
+      case vd @ DefDef(_, _, tpe, _)
+          if isValidSpan(tpe.span, vd.nameSpan) &&
+            tpe.span.start >= vd.nameSpan.end &&
+            !vd.symbol.isConstructor &&
+            !vd.symbol.is(Flags.Mutable) =>
+        if vd.symbol == vd.symbol.sourceSymbol then
+          Some(tpe.tpe, tpe.sourcePos, vd)
+        else None
+      case bd @ Bind(
+            name,
+            Ident(nme.WILDCARD),
+          ) =>
+        Some(bd.symbol.info, bd.namePos, bd)
+      case _ => None
+
+  private def isValidSpan(tpeSpan: Span, nameSpan: Span): Boolean =
+    tpeSpan.isZeroExtent &&
+      nameSpan.exists &&
+      !nameSpan.isZeroExtent
+
+end InferredType
+
+case class Synthetics(
+    decorations: List[Decoration],
+    definitions: Set[Int],
+):
+  def containsDef(offset: Int) = definitions(offset)
+  def add(decoration: Decoration, offset: Int) =
+    copy(
+      decorations = decoration :: decorations,
+      definitions = definitions + offset,
+    )
+  def add(decoration: Decoration) =
+    copy(decorations = decoration :: decorations)
+
+object Synthetics:
+  def empty: Synthetics = Synthetics(Nil, Set.empty)