Imported Upstream version 5.16.0.100

Former-commit-id: 38faa55fb9669e35e7d8448b15c25dc447f25767

mcs/tests/test-961.cs

@@ -0,0 +1,28 @@
+// Compiler options: -langversion:latest
+
+using System;
+
+public static class B {
+	public static void Main ()
+	{
+	}
+
+	static void Foo (this in int src)
+	{
+		D p = (in int a) => {};
+	}
+
+}
+
+delegate void D (in int arg);
+
+class M
+{
+	int this[in int a] { set { } }
+	public static implicit operator string (in M m) => null;
+	public M (in int arg) { }
+
+	public void Test2 (in int arg)
+	{
+	}
+}