Fix non-implicit constructor arg list handling with -Yimplicit-as-given

Author: jchyb

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

@@ -635,7 +635,7 @@ object desugar {
     ValDef(vparam.name, vparam.tpt, vparam.rhs)
       .withSpan(vparam.span)
       .withAttachmentsFrom(vparam)
-      .withMods(mods & (GivenOrImplicit | Erased | hasDefault | Tracked) | Param)
+      .withMods(mods & (GivenOrImplicit | Erased | hasDefault | Tracked | FromImplicit) | Param)
   }
 
   /** Desugar type def (not param): Under x.moduliity this can expand

compiler/src/dotty/tools/dotc/core/NamerOps.scala

@@ -63,7 +63,7 @@ object NamerOps:
     if !isConstructor then paramss
     else paramss match
       case TypeSymbols(tparams) :: paramss1 => tparams :: normalizeIfConstructor(paramss1, isConstructor)
-      case TermSymbols(vparam :: _) :: _ if vparam.is(Implicit) => Nil :: paramss
+      case TermSymbols(vparam :: _) :: _ if vparam.is(Implicit) || vparam.is(FromImplicit) => Nil :: paramss
       case _ =>
         if paramss.forall {
           case TermSymbols(vparams) => vparams.nonEmpty && vparams.head.is(Given)

tests/pos/i22482.scala

@@ -6,3 +6,7 @@ def bar()(implicit a: Int) : Unit = ???
 def main() =
   foo(0)
   bar()(0)
+
+class Foo(implicit hashA: Int):
+  // added empty param list, works only for implicits
+  def this(o: Int, h: Int) = this()(h)