fix: show zero extent references when using pc

Author: kasiaMarek

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

@@ -35,6 +35,8 @@ trait PcCollector[T]:
       parent: Option[Tree]
   )(tree: Tree| EndMarker, pos: SourcePosition, symbol: Option[Symbol]): T
 
+  def allowZeroExtentImplicits: Boolean = false
+
   def resultAllOccurences(): Set[T] =
     def noTreeFilter = (_: Tree) => true
     def noSoughtFilter = (_: Symbol => Boolean) => true
@@ -87,6 +89,10 @@ trait PcCollector[T]:
     def isCorrect =
       !span.isZeroExtent && span.exists && span.start < sourceText.size && span.end <= sourceText.size
 
+  extension (tree: Tree)
+    def isCorrectSpan =
+      tree.span.isCorrect || (allowZeroExtentImplicits && tree.symbol.is(Flags.Implicit))
+
   def traverseSought(
       filter: Tree => Boolean,
       soughtFilter: (Symbol => Boolean) => Boolean
@@ -107,7 +113,7 @@ trait PcCollector[T]:
          * All indentifiers such as:
          * val a = <<b>>
          */
-        case ident: Ident if ident.span.isCorrect && filter(ident) =>
+        case ident: Ident if ident.isCorrectSpan && filter(ident) =>
           // symbols will differ for params in different ext methods, but source pos will be the same
           if soughtFilter(_.sourcePos == ident.symbol.sourcePos)
           then
@@ -122,7 +128,7 @@ trait PcCollector[T]:
          * val x = new <<A>>(1)
          */
         case sel @ Select(New(t), _)
-            if sel.span.isCorrect &&
+            if sel.isCorrectSpan &&
               sel.symbol.isConstructor &&
               t.symbol == NoSymbol =>
           if soughtFilter(_ == sel.symbol.owner) then
@@ -137,7 +143,7 @@ trait PcCollector[T]:
          * val a = hello.<<b>>
          */
         case sel: Select
-          if sel.span.isCorrect && filter(sel) &&
+          if sel.isCorrectSpan && filter(sel) &&
             !sel.isForComprehensionMethod =>
           occurrences + collect(
             sel,

Diff for: presentation-compiler/src/main/dotty/tools/pc/PcReferencesProvider.scala

@@ -23,6 +23,8 @@ class PcReferencesProvider(
     request: ReferencesRequest,
 ) extends WithCompilationUnit(driver, request.file()) with PcCollector[Option[(String, Option[lsp4j.Range])]]:
 
+  override def allowZeroExtentImplicits: Boolean = true
+
   private def soughtSymbols =
     if(request.offsetOrSymbol().isLeft()) {
       val offsetParams = CompilerOffsetParams(
@@ -64,4 +66,4 @@ class PcReferencesProvider(
         }
         .toList
       case _ => Nil
-end PcReferencesProvider
+end PcReferencesProvider

Diff for: presentation-compiler/test/dotty/tools/pc/tests/PcReferencesSuite.scala

@@ -0,0 +1,86 @@
+package dotty.tools.pc.tests
+import dotty.tools.pc.base.BasePCSuite
+import dotty.tools.pc.utils.RangeReplace
+import scala.meta.internal.pc.PcReferencesRequest
+import scala.meta.internal.metals.CompilerVirtualFileParams
+import java.net.URI
+import scala.meta.internal.metals.EmptyCancelToken
+import org.eclipse.lsp4j.jsonrpc.messages.{Either => JEither}
+import scala.meta.internal.jdk.CollectionConverters.*
+
+import org.junit.Test
+
+class PcReferencesSuite extends BasePCSuite with RangeReplace {
+  def check(
+    original: String,
+  ): Unit =
+    val edit = original.replaceAll("(<<|>>)", "")
+    val expected = original.replaceAll("@@", "")
+    val base = original.replaceAll("(<<|>>|@@)", "")
+
+    val (code, offset) = params(edit, "Highlight.scala")
+    val ranges = presentationCompiler
+      .references(
+        PcReferencesRequest(
+          CompilerVirtualFileParams(
+            URI.create("file:/Highlight.scala"),
+            code,
+            EmptyCancelToken
+          ),
+          includeDefinition = false,
+          offsetOrSymbol = JEither.forLeft(offset)
+        )
+      )
+      .get()
+      .asScala
+      .flatMap(_.locations().asScala.map(_.getRange()))
+      .toList
+
+    assertEquals(
+      renderRangesAsString(base, ranges),
+      expected,
+      "references should match"
+    )
+
+  @Test def `implicit-args` =
+    check(
+      """|package example
+         |
+         |class Bar(i: Int)
+         |
+         |object Hello {
+         |  def m(i: Int)(implicit b: Bar) = ???
+         |  val foo = {
+         |    implicit val ba@@rr: Bar = new Bar(1)
+         |    m(3)<<>>
+         |  }
+         |}
+         |""".stripMargin
+    )
+
+  @Test def `implicit-args-2` =
+    check(
+      """|package example
+        |
+        |class Bar(i: Int)
+        |class Foo(implicit b: Bar)
+        |
+        |object Hello {
+        |  implicit val ba@@rr: Bar = new Bar(1)
+        |  val foo = new Foo<<>>
+        |}
+        |""".stripMargin
+    )
+
+  @Test def `case-class` =
+    check(
+      """|case class Ma@@in(i: Int)
+         |""".stripMargin
+    )
+
+  @Test def `case-class-with-implicit` =
+    check(
+      """"|case class A()(implicit val fo@@o: Int)
+          |""".stripMargin
+    )
+}

Diff for: presentation-compiler/test/dotty/tools/pc/utils/RangeReplace.scala

@@ -12,14 +12,21 @@ trait RangeReplace:
   def renderHighlightsAsString(
       code: String,
       highlights: List[DocumentHighlight]
+  ): String = renderRangesAsString(code, highlights.map(_.getRange()))
+
+  def renderRangesAsString(
+      code: String,
+      highlights: List[Range],
+      alreadyAddedMarkings: List[(Int, Int)] = Nil,
+      currentBase: Option[String] = None
   ): String =
     highlights
-      .foldLeft((code, immutable.List.empty[(Int, Int)])) {
-        case ((base, alreadyAddedMarkings), location) =>
-          replaceInRangeWithAdjustmens(
+      .foldLeft((currentBase.getOrElse(code), alreadyAddedMarkings)) {
+        case ((base, alreadyAddedMarkings), range) =>
+          replaceInRangeWithAdjustments(
             code,
             base,
-            location.getRange,
+            range,
             alreadyAddedMarkings
           )
       }
@@ -31,9 +38,9 @@ trait RangeReplace:
       prefix: String = "<<",
       suffix: String = ">>"
   ): String =
-    replaceInRangeWithAdjustmens(base, base, range, List(), prefix, suffix)._1
+    replaceInRangeWithAdjustments(base, base, range, List(), prefix, suffix)._1
 
-  protected def replaceInRangeWithAdjustmens(
+  protected def replaceInRangeWithAdjustments(
       code: String,
       currentBase: String,
       range: Range,