Test that would have caught recovery-expr crashes in 0788acb. NFC

Author: sam-mccall

clang/test/Sema/invalid-member.cpp

@@ -0,0 +1,7 @@
+// RUN: %clang_cc1 -verify -fsyntax-only %s
+void foo(); // expected-note {{requires 0 arguments}}
+class X {
+  decltype(foo(42)) invalid; // expected-error {{no matching function}}
+};
+// Should be able to evaluate sizeof without crashing.
+static_assert(sizeof(X) == 1, "No valid members");