Sema: Add missing test case for 63a5731

Author: slavapestov

test/Macros/bind_extensions_request_cycle.swift

@@ -0,0 +1,29 @@
+// RUN: %target-typecheck-verify-swift %s
+
+@attached(member) @attached(peer)
+public macro Foo(_: any P) = #externalMacro(module: "FooMacros", type: "FooMacro")
+// expected-warning@-1 {{external macro implementation type 'FooMacros.FooMacro' could not be found for macro 'Foo'; plugin for module 'FooMacros' not found}}
+// expected-note@-2 2 {{'Foo' declared here}}
+
+public protocol P {}
+
+@Foo(S.s)
+struct A {
+// expected-error@-1 2 {{external macro implementation type 'FooMacros.FooMacro' could not be found for macro 'Foo'; plugin for module 'FooMacros' not found}}
+  func a() {}
+}
+
+extension A {
+  struct Nested {}
+}
+
+// Binding this extension must not trigger macro expansion, because that
+// performs a qualified lookup of S.s, which fails because the extension
+// of P declared below has not been bound yet.
+extension A.Nested {}
+
+struct S: P {}
+
+extension P where Self == S {
+  static var s: Self { Self() }
+}