Backport "Remove artificial CURSOR added to code in the completions" to LTS (#22114)

Backports #20899 to the 3.3.5.

PR submitted by the release tooling.
[skip ci]

Author: WojciechMazur

compiler/src/dotty/tools/dotc/ast/NavigateAST.scala

@@ -3,6 +3,7 @@ package ast
 
 import core.Contexts.*
 import core.Decorators.*
+import core.StdNames
 import util.Spans.*
 import Trees.{Closure, MemberDef, DefTree, WithLazyFields}
 import dotty.tools.dotc.core.Types.AnnotatedType
@@ -74,21 +75,50 @@ object NavigateAST {
   def pathTo(span: Span, from: List[Positioned], skipZeroExtent: Boolean = false)(using Context): List[Positioned] = {
     def childPath(it: Iterator[Any], path: List[Positioned]): List[Positioned] = {
       var bestFit: List[Positioned] = path
-      while (it.hasNext) {
-        val path1 = it.next() match {
+      while (it.hasNext) do
+        val path1 = it.next() match
+          case sel: untpd.Select if isRecoveryTree(sel) => path
+          case sel: untpd.Ident  if isPatternRecoveryTree(sel) => path
           case p: Positioned if !p.isInstanceOf[Closure[?]] => singlePath(p, path)
           case m: untpd.Modifiers => childPath(m.productIterator, path)
           case xs: List[?] => childPath(xs.iterator, path)
           case _ => path
-        }
-        if ((path1 ne path) &&
-            ((bestFit eq path) ||
-             bestFit.head.span != path1.head.span &&
-             bestFit.head.span.contains(path1.head.span)))
+
+        if (path1 ne path) && ((bestFit eq path) || isBetterFit(bestFit, path1)) then
           bestFit = path1
-      }
+
       bestFit
     }
+
+    /**
+      * When choosing better fit we compare spans. If candidate span has starting or ending point inside (exclusive)
+      * current best fit it is selected as new best fit. This means that same spans are failing the first predicate.
+      *
+      * In case when spans start and end at same offsets we prefer non synthethic one.
+      */
+    def isBetterFit(currentBest: List[Positioned], candidate: List[Positioned]): Boolean =
+      if currentBest.isEmpty && candidate.nonEmpty then true
+      else if currentBest.nonEmpty && candidate.nonEmpty then
+        val bestSpan = currentBest.head.span
+        val candidateSpan = candidate.head.span
+
+        bestSpan != candidateSpan &&
+          envelops(bestSpan, candidateSpan) ||
+          bestSpan.contains(candidateSpan) && bestSpan.isSynthetic && !candidateSpan.isSynthetic
+      else false
+
+    def isRecoveryTree(sel: untpd.Select): Boolean =
+      sel.span.isSynthetic
+        && (sel.name == StdNames.nme.??? && sel.qualifier.symbol.name == StdNames.nme.Predef)
+
+    def isPatternRecoveryTree(ident: untpd.Ident): Boolean =
+      ident.span.isSynthetic && StdNames.nme.WILDCARD == ident.name
+
+    def envelops(a: Span, b: Span): Boolean =
+      !b.exists || a.exists && (
+        (a.start < b.start && a.end >= b.end ) || (a.start <= b.start && a.end > b.end)
+      )
+
     /*
      * Annotations trees are located in the Type
      */

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

@@ -119,16 +119,17 @@ object Completion:
       case _ =>
         ""
 
+  def naiveCompletionPrefix(text: String, offset: Int): String =
+    var i = offset - 1
+    while i >= 0 && text(i).isUnicodeIdentifierPart do i -= 1
+    i += 1 // move to first character
+    text.slice(i, offset)
+
   /**
    * Inspect `path` to determine the completion prefix. Only symbols whose name start with the
    * returned prefix should be considered.
    */
   def completionPrefix(path: List[untpd.Tree], pos: SourcePosition)(using Context): String =
-    def fallback: Int =
-      var i = pos.point - 1
-      while i >= 0 && Character.isUnicodeIdentifierPart(pos.source.content()(i)) do i -= 1
-      i + 1
-
     path match
       case GenericImportSelector(sel) =>
         if sel.isGiven then completionPrefix(sel.bound :: Nil, pos)
@@ -146,7 +147,7 @@ object Completion:
       case (tree: untpd.RefTree) :: _ if tree.name != nme.ERROR =>
         tree.name.toString.take(pos.span.point - tree.span.point)
 
-      case _ => pos.source.content.slice(fallback, pos.point).mkString
+      case _ => naiveCompletionPrefix(pos.source.content().mkString, pos.point)
 
 
   end completionPrefix

compiler/src/dotty/tools/dotc/parsing/Parsers.scala

@@ -398,7 +398,7 @@ object Parsers {
       false
     }
 
-    def errorTermTree(start: Offset): Tree = atSpan(start, in.offset, in.offset) { unimplementedExpr }
+    def errorTermTree(start: Offset): Tree = atSpan(Span(start, in.offset)) { unimplementedExpr }
 
     private var inFunReturnType = false
     private def fromWithinReturnType[T](body: => T): T = {

language-server/test/dotty/tools/languageserver/HoverTest.scala

@@ -227,7 +227,7 @@ class HoverTest {
   @Test def enums: Unit = {
     code"""|package example
            |enum TestEnum3:
-           | case ${m1}A${m2} // no tooltip
+           |  case ${m1}A${m2} // no tooltip
            |
            |"""
       .hover(m1 to m2, hoverContent("example.TestEnum3"))

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

@@ -13,7 +13,6 @@ import dotty.tools.dotc.core.Symbols.*
 import dotty.tools.dotc.interactive.Interactive
 import dotty.tools.dotc.interactive.InteractiveDriver
 import dotty.tools.dotc.util.SourceFile
-import dotty.tools.pc.AutoImports.*
 import dotty.tools.pc.completions.CompletionPos
 import dotty.tools.pc.utils.InteractiveEnrichments.*
 
@@ -67,7 +66,8 @@ final class AutoImportsProvider(
     val results = symbols.result.filter(isExactMatch(_, name))
 
     if results.nonEmpty then
-      val correctedPos = CompletionPos.infer(pos, params, path).toSourcePosition
+      val correctedPos =
+        CompletionPos.infer(pos, params, path, wasCursorApplied = false).toSourcePosition
       val mkEdit =
         path match
           // if we are in import section just specify full name

presentation-compiler/src/main/dotty/tools/pc/MetalsDriver.scala renamed to presentation-compiler/src/main/dotty/tools/pc/CachingDriver.scala

@@ -7,9 +7,11 @@ import dotty.tools.dotc.interactive.InteractiveDriver
 import dotty.tools.dotc.reporting.Diagnostic
 import dotty.tools.dotc.util.SourceFile
 
+import scala.compiletime.uninitialized
+
 /**
- * MetalsDriver is a wrapper class that provides a compilation cache for InteractiveDriver.
- * MetalsDriver skips running compilation if
+ * CachingDriver is a wrapper class that provides a compilation cache for InteractiveDriver.
+ * CachingDriver skips running compilation if
  * - the target URI of `run` is the same as the previous target URI
  * - the content didn't change since the last compilation.
  *
@@ -25,11 +27,9 @@ import dotty.tools.dotc.util.SourceFile
  * To avoid the complexity related to currentCtx,
  * we decided to cache only when the target URI only if the same as the previous run.
  */
-class MetalsDriver(
-    override val settings: List[String]
-) extends InteractiveDriver(settings):
+class CachingDriver(override val settings: List[String]) extends InteractiveDriver(settings):
 
-  @volatile private var lastCompiledURI: URI = _
+  @volatile private var lastCompiledURI: URI = uninitialized
 
   private def alreadyCompiled(uri: URI, content: Array[Char]): Boolean =
     compilationUnits.get(uri) match
@@ -53,4 +53,4 @@ class MetalsDriver(
     lastCompiledURI = uri
     diags
 
-end MetalsDriver
+end CachingDriver

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

@@ -14,7 +14,6 @@ import scala.meta.internal.pc.LabelPart.*
 import scala.meta.pc.InlayHintsParams
 import scala.meta.pc.SymbolSearch
 
-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

presentation-compiler/src/main/dotty/tools/pc/Scala3CompilerAccess.scala

@@ -8,13 +8,14 @@ import scala.meta.internal.pc.CompilerAccess
 import scala.meta.pc.PresentationCompilerConfig
 
 import dotty.tools.dotc.reporting.StoreReporter
+import dotty.tools.dotc.interactive.InteractiveDriver
 
 class Scala3CompilerAccess(
     config: PresentationCompilerConfig,
     sh: Option[ScheduledExecutorService],
     newCompiler: () => Scala3CompilerWrapper
 )(using ec: ExecutionContextExecutor, rc: ReportContext)
-    extends CompilerAccess[StoreReporter, MetalsDriver](
+    extends CompilerAccess[StoreReporter, InteractiveDriver](
       config,
       sh,
       newCompiler,

presentation-compiler/src/main/dotty/tools/pc/Scala3CompilerWrapper.scala

@@ -4,11 +4,12 @@ import scala.meta.internal.pc.CompilerWrapper
 import scala.meta.internal.pc.ReporterAccess
 
 import dotty.tools.dotc.reporting.StoreReporter
+import dotty.tools.dotc.interactive.InteractiveDriver
 
-class Scala3CompilerWrapper(driver: MetalsDriver)
-    extends CompilerWrapper[StoreReporter, MetalsDriver]:
+class Scala3CompilerWrapper(driver: InteractiveDriver)
+    extends CompilerWrapper[StoreReporter, InteractiveDriver]:
 
-  override def compiler(): MetalsDriver = driver
+  override def compiler(): InteractiveDriver = driver
 
   override def resetReporter(): Unit =
     val ctx = driver.currentCtx

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

@@ -33,11 +33,13 @@ import dotty.tools.pc.completions.CompletionProvider
 import dotty.tools.pc.InferExpectedType
 import dotty.tools.pc.completions.OverrideCompletions
 import dotty.tools.pc.buildinfo.BuildInfo
+import dotty.tools.pc.SymbolInformationProvider
+import dotty.tools.dotc.interactive.InteractiveDriver
 
 import org.eclipse.lsp4j.DocumentHighlight
 import org.eclipse.lsp4j.TextEdit
 import org.eclipse.lsp4j as l
-import dotty.tools.pc.SymbolInformationProvider
+
 
 case class ScalaPresentationCompiler(
     buildTargetIdentifier: String = "",
@@ -76,14 +78,20 @@ case class ScalaPresentationCompiler(
   override def withReportsLoggerLevel(level: String): PresentationCompiler =
     copy(reportsLevel = ReportLevel.fromString(level))
 
-  val compilerAccess: CompilerAccess[StoreReporter, MetalsDriver] =
+  val compilerAccess: CompilerAccess[StoreReporter, InteractiveDriver] =
     Scala3CompilerAccess(
       config,
       sh,
-      () => new Scala3CompilerWrapper(newDriver)
-    )(using
-      ec
-    )
+      () => new Scala3CompilerWrapper(CachingDriver(driverSettings))
+    )(using ec)
+
+  val driverSettings =
+    val implicitSuggestionTimeout = List("-Ximport-suggestion-timeout", "0")
+    val defaultFlags = List("-color:never")
+    val filteredOptions = removeDoubleOptions(options.filterNot(forbiddenOptions))
+
+    filteredOptions ::: defaultFlags ::: implicitSuggestionTimeout ::: "-classpath" :: classpath
+      .mkString(File.pathSeparator) :: Nil
 
   private def removeDoubleOptions(options: List[String]): List[String] =
     options match
@@ -92,19 +100,6 @@ case class ScalaPresentationCompiler(
       case head :: tail => head :: removeDoubleOptions(tail)
       case Nil => options
 
-  def newDriver: MetalsDriver =
-    val implicitSuggestionTimeout = List("-Ximport-suggestion-timeout", "0")
-    val defaultFlags = List("-color:never")
-    val filteredOptions = removeDoubleOptions(
-      options.filterNot(forbiddenOptions)
-    )
-    val settings =
-      filteredOptions ::: defaultFlags ::: implicitSuggestionTimeout ::: "-classpath" :: classpath
-        .mkString(
-          File.pathSeparator
-        ) :: Nil
-    new MetalsDriver(settings)
-
   override def semanticTokens(
       params: VirtualFileParams
   ): CompletableFuture[ju.List[Node]] =
@@ -146,6 +141,7 @@ case class ScalaPresentationCompiler(
       new CompletionProvider(
         search,
         driver,
+        () => InteractiveDriver(driverSettings),
         params,
         config,
         buildTargetIdentifier,