bugfix: add multiline comment completion

mtags/src/main/scala-2/scala/meta/internal/pc/MetalsGlobal.scala

@@ -54,6 +54,7 @@ class MetalsGlobal(
     with completions.ScalaCliCompletions
     with completions.MillIvyCompletions
     with completions.SbtLibCompletions
+    with completions.MultilineCommentCompletions
     with Signatures
     with Compat
     with GlobalProxy

mtags/src/main/scala-2/scala/meta/internal/pc/completions/Completions.scala

@@ -498,6 +498,8 @@ trait Completions { this: MetalsGlobal =>
         SbtLibCompletion(coursierComplete, pos, dep)
       case ScalaCliExtractor(dep) =>
         ScalaCliCompletion(coursierComplete, pos, text, dep)
+      case _ if isMultilineCommentStart(pos, text) =>
+        MultilineCommentCompletion(editRange, pos, text)
       case _ if isScaladocCompletion(pos, text) =>
         val associatedDef = onUnitOf(pos.source) { unit =>
           new AssociatedMemberDefFinder(pos).findAssociatedDef(unit.body)

mtags/src/main/scala-2/scala/meta/internal/pc/completions/MultilineCommentCompletion.scala

@@ -0,0 +1,43 @@
+package scala.meta.internal.pc.completions
+
+import scala.meta.internal.pc.MetalsGlobal
+
+import org.eclipse.{lsp4j => l}
+
+trait MultilineCommentCompletions { this: MetalsGlobal =>
+  case class MultilineCommentCompletion(
+      editRange: l.Range,
+      pos: Position,
+      text: String
+  ) extends CompletionPosition {
+
+    override def contribute: List[TextEditMember] = {
+      val newText =
+        if (clientSupportsSnippets) s" $$0 */"
+        else s" */"
+      List(
+        new TextEditMember(
+          "Multiline Comment",
+          new l.TextEdit(
+            editRange,
+            newText
+          ),
+          completionsSymbol("Multiline"),
+          label = Some("/* */"),
+          detail = Some("Multiline Comment")
+        )
+      )
+    }
+  }
+
+  protected def isMultilineCommentStart(
+      pos: Position,
+      text: String
+  ): Boolean = {
+    pos.isDefined &&
+    pos.point >= 2 &&
+    text.charAt(pos.point - 2) == '/' &&
+    text.charAt(pos.point - 1) == '*'
+  }
+
+}

mtags/src/main/scala-3/scala/meta/internal/pc/completions/Completions.scala

@@ -359,6 +359,15 @@ class Completions(
     path match
       case ScalaCliCompletions(dependency) =>
         (ScalaCliCompletions.contribute(dependency), true)
+
+      case _
+          if MultilineCommentCompletion.isMultilineCommentCompletion(
+            pos,
+            text,
+          ) =>
+        val values = MultilineCommentCompletion.contribute(config)
+        (values, true)
+
       case _ if ScaladocCompletions.isScaladocCompletion(pos, text) =>
         val values = ScaladocCompletions.contribute(pos, text, config)
         (values, true)

mtags/src/main/scala-3/scala/meta/internal/pc/completions/MultilineCommentCompletion.scala

@@ -0,0 +1,16 @@
+package scala.meta.internal.pc.completions
+
+import scala.meta.pc.PresentationCompilerConfig
+
+import dotty.tools.dotc.util.SourcePosition
+
+object MultilineCommentCompletion:
+
+  def contribute(config: PresentationCompilerConfig): List[CompletionValue] =
+    val newText = if config.isCompletionSnippetsEnabled then " $0 */" else " */"
+    List(CompletionValue.document("/* */", newText, "Multiline Comment"))
+
+  def isMultilineCommentCompletion(pos: SourcePosition, text: String): Boolean =
+    pos.point >= 2 &&
+      text.charAt(pos.point - 2) == '/' &&
+      text.charAt(pos.point - 1) == '*'

tests/cross/src/test/scala/tests/pc/CompletionSuite.scala

@@ -1921,4 +1921,20 @@ class CompletionSuite extends BaseCompletionSuite {
        |""".stripMargin,
   )
 
+  checkEdit(
+    "multiline-comment",
+    """|package a
+       |object O {
+       |  /*@@
+       |  def f = 1
+       |}
+       |""".stripMargin,
+    """|package a
+       |object O {
+       |  /* $0 */
+       |  def f = 1
+       |}
+       |""".stripMargin,
+  )
+
 }