Fix hasMatchingMember handling NoDenotation

Author: dwijnand

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

@@ -2021,7 +2021,7 @@ class TypeComparer(@constructorOnly initctx: Context) extends ConstraintHandling
         || (tp1.isStable && isSubType(TermRef(tp1, m.symbol), tp2.refinedInfo))
 
       tp1.member(name) match // inlined hasAltWith for performance
-        case mbr: SingleDenotation => qualifies(mbr)
+        case mbr: SingleDenotation => mbr.exists && qualifies(mbr)
         case mbr => mbr hasAltWith qualifies
     }
 

tests/neg/i17581.check

@@ -0,0 +1,7 @@
+-- [E007] Type Mismatch Error: tests/neg/i17581.scala:9:6 --------------------------------------------------------------
+9 |  foo(test) // error // was NoSuchMethodException
+  |      ^^^^
+  |      Found:    (test : Test)
+  |      Required: Object{def bar: Any}
+  |
+  | longer explanation available when compiling with `-explain`

tests/neg/i17581.scala

@@ -0,0 +1,9 @@
+import scala.reflect.Selectable.reflectiveSelectable
+
+class Test
+
+def foo[A <: { def bar: Any }](ob: A) = ob.bar
+
+@main def main =
+  val test = new Test
+  foo(test) // error // was NoSuchMethodException

tests/neg/i7812.scala

@@ -1,3 +1,3 @@
 def f(): Any = ???
 var f: (UndefinedA & UndefinedB) { val x: Int } = ??? // error // error
-val a = f // error
+val a = f