Bypass proxiability check in unresolved context (#255)

Author: mingxwa

proxy.h

@@ -332,11 +332,19 @@ struct overload_traits<R(Args...) const&& noexcept>
     : overload_traits_impl<qualifier_type::const_rv, true, R, Args...> {};
 
 template <class O>
-struct overload_substitution_traits : inapplicable_traits
-    { template <class> using type = O; };
+struct overload_substitution_traits : inapplicable_traits {
+  template <class> using type = O;
+  template <bool IsDirect, class D, class P>
+  static constexpr bool applicable_ptr =
+      overload_traits<O>::template applicable_ptr<IsDirect, D, P>;
+};
 template <template <class> class O>
 struct overload_substitution_traits<facade_aware_overload_t<O>>
-    : applicable_traits { template <class F> using type = O<F>; };
+    : applicable_traits {
+  template <class F> using type = O<F>;
+  template <bool IsDirect, class D, class P>
+  static constexpr bool applicable_ptr = true;
+};
 template <class O, class F>
 using substituted_overload_t =
     typename overload_substitution_traits<O>::template type<F>;
@@ -393,7 +401,7 @@ struct conv_traits_impl<C, F, Os...> : applicable_traits {
 
   template <class P>
   static constexpr bool applicable_ptr =
-      (overload_traits<substituted_overload_t<Os, F>>::template applicable_ptr<
+      (overload_substitution_traits<Os>::template applicable_ptr<
           C::is_direct, typename C::dispatch_type, P> && ...);
 };
 template <class C, class F> struct conv_traits : inapplicable_traits {};

tests/proxy_regression_tests.cpp

@@ -2,8 +2,41 @@
 // Licensed under the MIT License.
 
 #include <gtest/gtest.h>
+#include <vector>
 #include "proxy.h"
 
+namespace proxy_regression_tests_details {
+
+template <class It, class F>
+bool operator==(const It& it, const pro::proxy<F>& rhs) noexcept
+    requires(!std::is_same_v<It, pro::proxy<F>>) {
+  return typeid(It) == proxy_typeid(rhs) && it == proxy_cast<const It&>(rhs);
+}
+
+template <class F>
+using SelfComparisonOverload = bool(const pro::proxy<F>& rhs) const noexcept;
+
+template <class T>
+struct Iterator : pro::facade_builder
+    ::support_direct_rtti
+    ::restrict_layout<4 * sizeof(void*)>
+    ::add_direct_convention<pro::operator_dispatch<"++">, void() noexcept>
+    ::add_direct_convention<pro::operator_dispatch<"!=">, pro::facade_aware_overload_t<SelfComparisonOverload>>
+    ::add_convention<pro::implicit_conversion_dispatch, T&() const noexcept>
+    ::build {};
+
+PRO_DEF_MEM_DISPATCH(MemBegin, begin);
+PRO_DEF_MEM_DISPATCH(MemEnd, end);
+template <class T>
+struct Range : pro::facade_builder
+    ::add_convention<MemBegin, pro::proxy<Iterator<T>>()>
+    ::template add_convention<MemEnd, pro::proxy<Iterator<T>>()>
+    ::build {};
+
+}  // namespace proxy_regression_tests_details
+
+namespace details = proxy_regression_tests_details;
+
 // https://github.com/microsoft/proxy/issues/213
 TEST(ProxyRegressionTests, TestUnexpectedCompilerWarning) {
   struct MyTrivialFacade : pro::facade_builder
@@ -17,3 +50,14 @@ TEST(ProxyRegressionTests, TestUnexpectedCompilerWarning) {
   (*p)();
   EXPECT_EQ(side_effect, 1);
 }
+
+// https://github.com/microsoft/proxy/issues/254
+TEST(ProxyRegressionTests, TestProxiableSelfDependency) {
+  std::vector<int> original{1, 2, 123};
+  std::vector<int> expected;
+  pro::proxy<details::Range<int>> p = &original;
+  for (int i : *p) {
+    expected.push_back(i);
+  }
+  EXPECT_EQ(expected, original);
+}