Patch x: _* into x* (not x *) (#18814)

Author: nicolasstucki

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

@@ -2344,7 +2344,7 @@ object Parsers {
               in.sourcePos(uscoreStart),
               future)
             if sourceVersion == `future-migration` then
-              patch(source, Span(t.span.end, in.lastOffset), " *")
+              patch(source, Span(t.span.end, in.lastOffset), "*")
           else if opStack.nonEmpty then
             report.errorOrMigrationWarning(
               em"""`_*` can be used only for last argument of method application.
@@ -2973,12 +2973,6 @@ object Parsers {
       case p =>
         p
 
-    private def warnStarMigration(p: Tree) =
-      report.errorOrMigrationWarning(
-        em"The syntax `x: _*` is no longer supported for vararg splices; use `x*` instead",
-        in.sourcePos(startOffset(p)),
-        from = future)
-
     /**  InfixPattern ::= SimplePattern {id [nl] SimplePattern}
      */
     def infixPattern(): Tree =

tests/rewrites/rewrites3x.check

@@ -0,0 +1,10 @@
+import scala.{collection as coll, runtime as _, *}
+import coll.*
+
+def f(xs: Int*) = xs.sum
+def test =
+  f(List(1, 2, 3)*)
+
+def g = { implicit (x: Int) =>
+  x + 1
+}