Don't show enum completions in new keyword context (#20304)

Fixes #19968
[Cherry-picked c5f2064]

Author: rochala

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

@@ -75,7 +75,7 @@ object Completion:
     customMatcher: Option[Name => Boolean] = None
   )(using Context): CompletionMap =
     val adjustedPath = typeCheckExtensionConstructPath(untpdPath, tpdPath, pos)
-    computeCompletions(pos, mode, rawPrefix, adjustedPath, customMatcher)
+    computeCompletions(pos, mode, rawPrefix, adjustedPath, untpdPath, customMatcher)
 
   /**
    * Inspect `path` to determine what kinds of symbols should be considered.
@@ -199,12 +199,16 @@ object Completion:
     .flatten.getOrElse(tpdPath)
 
   private def computeCompletions(
-    pos: SourcePosition, mode: Mode, rawPrefix: String, adjustedPath: List[tpd.Tree], matches: Option[Name => Boolean]
+    pos: SourcePosition,
+    mode: Mode, rawPrefix: String,
+    adjustedPath: List[tpd.Tree],
+    untpdPath: List[untpd.Tree],
+    matches: Option[Name => Boolean]
   )(using Context): CompletionMap =
     val hasBackTick = rawPrefix.headOption.contains('`')
     val prefix = if hasBackTick then rawPrefix.drop(1) else rawPrefix
     val matches0 = matches.getOrElse(_.startsWith(prefix))
-    val completer = new Completer(mode, pos, matches0)
+    val completer = new Completer(mode, pos, untpdPath, matches0)
 
     val result = adjustedPath match
       // Ignore synthetic select from `This` because in code it was `Ident`
@@ -279,6 +283,12 @@ object Completion:
     if denot.isType then denot.symbol.showFullName
     else denot.info.widenTermRefExpr.show
 
+
+  def isInNewContext(untpdPath: List[untpd.Tree]): Boolean =
+    untpdPath match
+      case _ :: untpd.New(selectOrIdent: (untpd.Select | untpd.Ident)) :: _ => true
+      case _ => false
+
   /** Include in completion sets only symbols that
    *   1. is not absent (info is not NoType)
    *   2. are not a primary constructor,
@@ -290,7 +300,11 @@ object Completion:
    *   8. symbol is not a constructor proxy module when in type completion mode
    *   9. have same term/type kind as name prefix given so far
    */
-  def isValidCompletionSymbol(sym: Symbol, completionMode: Mode)(using Context): Boolean =
+  def isValidCompletionSymbol(sym: Symbol, completionMode: Mode, isNew: Boolean)(using Context): Boolean =
+
+    lazy val isEnum = sym.is(Enum) ||
+      (sym.companionClass.exists && sym.companionClass.is(Enum))
+
     sym.exists &&
     !sym.isAbsent() &&
     !sym.isPrimaryConstructor &&
@@ -300,6 +314,7 @@ object Completion:
     !sym.isPackageObject &&
     !sym.is(Artifact) &&
     !(completionMode.is(Mode.Type) && sym.isAllOf(ConstructorProxyModule)) &&
+    !(isNew && isEnum) &&
     (
          (completionMode.is(Mode.Term) && (sym.isTerm || sym.is(ModuleClass))
       || (completionMode.is(Mode.Type) && (sym.isType || sym.isStableMember)))
@@ -323,7 +338,7 @@ object Completion:
    *  For the results of all `xyzCompletions` methods term names and type names are always treated as different keys in the same map
    *  and they never conflict with each other.
    */
-  class Completer(val mode: Mode, pos: SourcePosition, matches: Name => Boolean):
+  class Completer(val mode: Mode, pos: SourcePosition, untpdPath: List[untpd.Tree], matches: Name => Boolean):
     /** Completions for terms and types that are currently in scope:
      *  the members of the current class, local definitions and the symbols that have been imported,
      *  recursively adding completions from outer scopes.
@@ -530,7 +545,7 @@ object Completion:
       // There are four possible ways for an extension method to be applicable
 
       // 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, matches)
+      val termCompleter = new Completer(Mode.Term, pos, untpdPath, matches)
       val extMethodsInScope = termCompleter.scopeCompletions.toList.flatMap:
         case (name, denots) => denots.collect:
           case d: SymDenotation if d.isTerm && d.termRef.symbol.is(Extension) => (d.termRef, name.asTermName)
@@ -557,14 +572,16 @@ object Completion:
       }
       extMethodsWithAppliedReceiver.groupByName
 
+    lazy val isNew: Boolean = isInNewContext(untpdPath)
+
     /** Include in completion sets only symbols that
      *   1. match the filter method,
      *   2. satisfy [[Completion.isValidCompletionSymbol]]
      */
     private def include(denot: SingleDenotation, nameInScope: Name)(using Context): Boolean =
       matches(nameInScope) &&
       completionsFilter(NoType, nameInScope) &&
-      isValidCompletionSymbol(denot.symbol, mode)
+      isValidCompletionSymbol(denot.symbol, mode, isNew)
 
     private def extractRefinements(site: Type)(using Context): Seq[SingleDenotation] =
       site match

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

@@ -1704,4 +1704,23 @@ class CompletionTest {
      .completion(m1, Set(
        ("getOrElse", Method, "[V1 >: String](key: Int, default: => V1): V1"),
      ))
+
+  @Test def noEnumCompletionInNewContext: Unit =
+    code"""|enum TestEnum:
+           |  case TestCase
+           |object M:
+           |  TestEnu$m1
+           |  TestEnum.TestCa$m2
+           |  val x: TestEnu$m3
+           |  val y: TestEnum.Tes$m4
+           |  new TestEnu$m5
+           |  new TestEnum.TestCas$m6
+           |"""
+     .completion(m1, Set(("TestEnum", Module, "TestEnum")))
+     .completion(m2, Set(("TestCase", Field, "TestEnum")))
+     .completion(m3, Set(("TestEnum", Module, "TestEnum"), ("TestEnum", Class, "TestEnum")))
+     .completion(m4, Set(("TestCase", Field, "TestEnum")))
+     .completion(m5, Set())
+     .completion(m6, Set())
+
 }

presentation-compiler/src/main/dotty/tools/pc/completions/Completions.scala

@@ -72,10 +72,7 @@ class Completions(
       case _ :: (_: (Import | Export)) :: _ => false
       case _ => true
 
-  private lazy val isNew: Boolean =
-    path match
-      case _ :: New(selectOrIdent: (Select | Ident)) :: _ => true
-      case _ => false
+  private lazy val isNew: Boolean = Completion.isInNewContext(adjustedPath)
 
   def includeSymbol(sym: Symbol)(using Context): Boolean =
     def hasSyntheticCursorSuffix: Boolean =
@@ -539,7 +536,7 @@ class Completions(
     val query = completionPos.query
     if completionMode.is(Mode.Scope) && query.nonEmpty then
       val visitor = new CompilerSearchVisitor(sym =>
-        if Completion.isValidCompletionSymbol(sym, completionMode) &&
+        if Completion.isValidCompletionSymbol(sym, completionMode, isNew) &&
           !(sym.is(Flags.ExtensionMethod) || (sym.maybeOwner.is(Flags.Implicit) && sym.maybeOwner.isClass))
         then
           indexedContext.lookupSym(sym) match

presentation-compiler/test/dotty/tools/pc/tests/completion/CompletionSuite.scala

@@ -1877,3 +1877,34 @@ class CompletionSuite extends BaseCompletionSuite:
         |""".stripMargin,
       topLines = Some(2)
     )
+
+  @Test def `no-enum-completions-in-new-context` =
+    check(
+      """enum TestEnum:
+        |  case TestCase
+        |object M:
+        |  new TestEnu@@
+        |""".stripMargin,
+      ""
+    )
+
+  @Test def `no-enum-case-completions-in-new-context` =
+    check(
+      """enum TestEnum:
+        |  case TestCase
+        |object M:
+        |  new TestEnum.TestCas@@
+        |""".stripMargin,
+      ""
+    )
+
+  @Test def `deduplicated-enum-completions` =
+    check(
+      """enum TestEnum:
+        |  case TestCase
+        |object M:
+        |  val x: TestEn@@
+        |""".stripMargin,
+      """TestEnum test
+        |""".stripMargin,
+    )