Pretype args of overloaded app with common expected type of alternatives ..

before skipping the parameter list, to disambiguate with subsequent clauses

Fixes scala#23011

Author: EugeneFlesselle

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

@@ -2447,10 +2447,12 @@ trait Applications extends Compatibility {
         deepPt match
           case pt @ FunProto(_, PolyProto(targs, resType)) =>
             // try to narrow further with snd argument list and following type params
+            pretypeArgs(candidates, pt)
             resolveMapped(candidates,
               skipParamClause(pt.typedArgs().tpes, targs.tpes), resType)
           case pt @ FunProto(_, resType: FunOrPolyProto) =>
             // try to narrow further with snd argument list
+            pretypeArgs(candidates, pt)
             resolveMapped(candidates,
               skipParamClause(pt.typedArgs().tpes, Nil), resType)
           case _ =>

tests/pos/i23011.scala

@@ -0,0 +1,16 @@
+
+type X = Double => Unit
+def g(x: Double): Unit = ???
+def g(x: String): Unit = ???
+
+def f1(x: X) = ???
+
+def f2(x: X, y: Int) = ???
+def f2(x: X, y: Boolean) = ???
+
+def f3(x: X)(y: Int) = ???
+def f3(x: X)(y: Boolean) = ???
+
+val r1 = f1(g) // ok
+val r2 = f2(g, 1) // ok
+val r3 = f3(g)(1) // was error: ambiguous overload for g