[embedded] Add a test to exercise multi-protocol class-bound existentials

Author: kubamracek

test/embedded/existential-class-bound9.swift

@@ -0,0 +1,35 @@
+// RUN: %target-run-simple-swift(-enable-experimental-feature Embedded -parse-as-library -wmo) | %FileCheck %s
+// RUN: %target-run-simple-swift(-enable-experimental-feature Embedded -parse-as-library -wmo -O) | %FileCheck %s
+// RUN: %target-run-simple-swift(-enable-experimental-feature Embedded -parse-as-library -wmo -Osize) | %FileCheck %s
+
+// REQUIRES: swift_in_compiler
+// REQUIRES: executable_test
+// REQUIRES: optimized_stdlib
+// REQUIRES: OS=macosx || OS=linux-gnu
+
+protocol ClassBound: AnyObject {
+    func foo()
+}
+
+protocol OtherProtocol: AnyObject {
+    func bar()
+}
+
+class MyClass: ClassBound, OtherProtocol {
+    func foo() { print("MyClass.foo()") }
+    func bar() { print("MyClass.bar()") }
+}
+
+func test(existential: any ClassBound & OtherProtocol) {
+    existential.foo()
+    existential.bar()
+}
+
+@main
+struct Main {
+    static func main() {
+        test(existential: MyClass())
+        // CHECK: MyClass.foo()
+        // CHECK: MyClass.bar()
+    }
+}