Add more tests. NFC.

Author: dtcxzyw

clang/test/SemaCXX/pmf-conversions.cpp

@@ -15,6 +15,10 @@ using pf_type_mismatched = void (*)(S*, int);
 #pragma clang diagnostic push
 #pragma clang diagnostic ignored "-Wpmf-conversions"
 
+// constexpr pmf conversions are not supported yet.
+constexpr pf_type method_constexpr = reinterpret_cast<pf_type>(&S::method); // expected-error {{constexpr variable 'method_constexpr' must be initialized by a constant expression}} expected-note {{reinterpret_cast is not allowed in a constant expression}}
+pf_type method = reinterpret_cast<pf_type>(&S::method);
+
 void pmf_convert_no_object(pmf_type method, pm_type field) {
   (void)reinterpret_cast<pf_type>(&S::method);
   (void)reinterpret_cast<pf_type>(method);