Backport "presentation compiler: Bugfix for semantic tokens and synthetic decorations" to LTS (#20780)

Backports #18955 to the LTS branch.

PR submitted by the release tooling.
[skip ci]

Author: WojciechMazur

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

@@ -129,7 +129,7 @@ final class PcSemanticTokensProvider(
         if sym.isGetter | sym.isSetter then
           getTypeId(SemanticTokenTypes.Variable)
         else getTypeId(SemanticTokenTypes.Method) // "def"
-      else if isPredefClass(sym) then
+      else if sym.isTerm && sym.info.typeSymbol.is(Flags.Module)  then
         getTypeId(SemanticTokenTypes.Class) // "class"
       else if sym.isTerm &&
         (!sym.is(Flags.Param) || sym.is(Flags.ParamAccessor))
@@ -151,7 +151,4 @@ final class PcSemanticTokensProvider(
     TokenNode(pos.start, pos.`end`, typ, mod)
   end makeNode
 
-  def isPredefClass(sym: Symbol)(using Context) =
-    sym.is(Flags.Method) && sym.info.resultType.typeSymbol.is(Flags.Module)
-
 end PcSemanticTokensProvider

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

@@ -46,7 +46,7 @@ final class PcSyntheticDecorationsProvider(
 
   def provide(): List[SyntheticDecoration] =
     val deepFolder = DeepFolder[Synthetics](collectDecorations)
-    deepFolder(Synthetics.empty, tpdTree).decorations
+    deepFolder(Synthetics.empty, tpdTree).result()
 
   def collectDecorations(
       decorations: Synthetics,
@@ -256,11 +256,23 @@ case class Synthetics(
   def containsDef(offset: Int) = definitions(offset)
   def add(decoration: Decoration, offset: Int) =
     copy(
-      decorations = decoration :: decorations,
+      decorations = addDecoration(decoration),
       definitions = definitions + offset,
     )
   def add(decoration: Decoration) =
-    copy(decorations = decoration :: decorations)
+    copy (
+      decorations = addDecoration(decoration)
+    )
+
+  // If method has both type parameter and implicit parameter, we want the type parameter decoration to be displayed first,
+  // but it's added second. This method adds the decoration to the right position in the list.
+  private def addDecoration(decoration: Decoration): List[Decoration] =
+    val atSamePos =
+      decorations.takeWhile(_.range.getStart() == decoration.range.getStart())
+    (atSamePos :+ decoration) ++ decorations.drop(atSamePos.size)
+
+  def result(): List[Decoration] = decorations.reverse
+end Synthetics
 
 object Synthetics:
   def empty: Synthetics = Synthetics(Nil, Set.empty)

presentation-compiler/test/dotty/tools/pc/tests/decorations/SyntheticDecorationsSuite.scala

@@ -483,4 +483,18 @@ class SyntheticDecorationsSuite extends BaseSyntheticDecorationsSuite:
          |}
          |""".stripMargin
     )
+   
+  @Test def `ord` = 
+    check(
+      """
+        |object Main {
+        |  val ordered = "acb".sorted
+        |}
+        |""".stripMargin,
+      """
+        |object Main {
+        |  val ordered: String = augmentString("acb").sorted[Char](Char)
+        |}
+        |""".stripMargin
+    )
 

presentation-compiler/test/dotty/tools/pc/tests/tokens/SemanticTokensSuite.scala

@@ -278,13 +278,37 @@ class SemanticTokensSuite extends BaseSemanticTokensSuite:
     check(
       """
         |object <<Main>>/*class*/ {
-        |  val <<a>>/*variable,definition,readonly*/ = <<List>>/*class*/(1,2,3)
-        |  val <<y>>/*variable,definition,readonly*/ = <<Vector>>/*class*/(1,2)
-        |  val <<z>>/*variable,definition,readonly*/ = <<Set>>/*class*/(1,2,3)
-        |  val <<w>>/*variable,definition,readonly*/ = <<Right>>/*class*/(1)
+        |val <<a>>/*variable,definition,readonly*/ = <<List>>/*class*/(1,2,3)
+        |val <<y>>/*variable,definition,readonly*/ = <<Vector>>/*class*/(1,2)
+        |val <<z>>/*variable,definition,readonly*/ = <<Set>>/*class*/(1,2,3)
+        |val <<w>>/*variable,definition,readonly*/ = <<Right>>/*class*/(1)
         |}""".stripMargin
     )
 
+  @Test def `predef1` =
+    check(
+      """
+        |object <<Main>>/*class*/ {
+        |  val <<a>>/*variable,definition,readonly*/ = <<List>>/*class*/(1,2,3)
+        |  val <<y>>/*class,definition*/ = <<List>>/*class*/
+        |  val <<z>>/*class,definition*/ = <<scala>>/*namespace*/.<<collection>>/*namespace*/.<<immutable>>/*namespace*/.<<List>>/*class*/
+        |}
+        |""".stripMargin
+    )
+
+  @Test def `val-object` =
+    check(
+      """
+        |case class <<X>>/*class*/(<<a>>/*variable,declaration,readonly*/: <<Int>>/*class,abstract*/)
+        |object <<X>>/*class*/
+        |
+        |object <<Main>>/*class*/ {
+        |  val <<x>>/*class,definition*/ = <<X>>/*class*/
+        |  val <<y>>/*variable,definition,readonly*/ = <<X>>/*class*/(1)
+        |}
+        |""".stripMargin
+    )
+
   @Test def `case-class` =
     check(
       """|case class <<Foo>>/*class*/(<<i>>/*variable,declaration,readonly*/: <<Int>>/*class,abstract*/, <<j>>/*variable,declaration,readonly*/: <<Int>>/*class,abstract*/)