Take type bounds into account for overloading resolution

When resolving overloaded polymorphic variants with explicit type
arguments, discard those variants where the given argument does not
fit the type parameter bounds.

Fixes #11015

Author: odersky

compiler/src/dotty/tools/dotc/typer/Applications.scala

@@ -1884,7 +1884,13 @@ trait Applications extends Compatibility {
       case pt @ PolyProto(targs1, pt1) =>
         val alts1 = alts.filter(pt.canInstantiate)
         if isDetermined(alts1) then alts1
-        else resolveMapped(alts1, _.widen.appliedTo(targs1.tpes), pt1)
+        else
+          def withinBounds(alt: TermRef) = alt.widen match
+            case tp: PolyType =>
+              TypeOps.boundsViolations(targs1, tp.paramInfos, _.substParams(tp, _), NoType).isEmpty
+          val alts2 = alts1.filter(withinBounds)
+          if isDetermined(alts2) then alts2
+          else resolveMapped(alts1, _.widen.appliedTo(targs1.tpes), pt1)
 
       case defn.FunctionOf(args, resultType, _, _) =>
         narrowByTypes(alts, args, resultType)

tests/neg/tcpoly_overloaded.scala

@@ -21,5 +21,5 @@ trait Test {
     def flatMap[S]
             (f: T => List[S], foo: Int): List[S]  = sys.error("foo")
   }
-  val l: MList[String] = moo.flatMap[String, List, Any, MList]((x: Int) => new MList("String"))
+  val l: MList[String] = moo.flatMap[String, List, Any, MList]((x: Int) => new MList("String")) // error: no alternative matches
 }

tests/pos/i11015.scala

@@ -0,0 +1,6 @@
+import annotation.targetName
+object Foo:
+   def apply[A <: Int]: Int = 0
+   @targetName("applyS") def apply[B <: String]: String = "0"
+
+def test = Foo[Int]