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diff --git a/src/boost/libs/outcome/test/tests/issue0203.cpp b/src/boost/libs/outcome/test/tests/issue0203.cpp
new file mode 100644
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+++ b/src/boost/libs/outcome/test/tests/issue0203.cpp
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+/* Unit testing for outcomes
+(C) 2013-2020 Niall Douglas <http://www.nedproductions.biz/> (1 commit)
+
+
+Boost Software License - Version 1.0 - August 17th, 2003
+
+Permission is hereby granted, free of charge, to any person or organization
+obtaining a copy of the software and accompanying documentation covered by
+this license (the "Software") to use, reproduce, display, distribute,
+execute, and transmit the Software, and to prepare derivative works of the
+Software, and to permit third-parties to whom the Software is furnished to
+do so, all subject to the following:
+
+The copyright notices in the Software and this entire statement, including
+the above license grant, this restriction and the following disclaimer,
+must be included in all copies of the Software, in whole or in part, and
+all derivative works of the Software, unless such copies or derivative
+works are solely in the form of machine-executable object code generated by
+a source language processor.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
+SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
+FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
+ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+DEALINGS IN THE SOFTWARE.
+*/
+
+#include <boost/outcome/std_result.hpp>
+#include <boost/outcome/try.hpp>
+#include <boost/test/unit_test.hpp>
+#include <boost/test/unit_test_monitor.hpp>
+
+namespace outcome = BOOST_OUTCOME_V2_NAMESPACE;
+
+enum class error
+{
+  test,
+  abcde
+};
+
+class error_category_impl : public std::error_category
+{
+public:
+  const char *name() const noexcept override { return "test"; }
+
+  std::string message(int code) const noexcept override
+  {
+    switch(static_cast<error>(code))
+    {
+    case error::test:
+      return "test";
+    case error::abcde:
+      return "abcde";
+    }
+    return "unknown";
+  }
+};
+const std::error_category &error_category() noexcept
+{
+  static error_category_impl instance;
+  return instance;
+}
+
+boost::system::error_code make_error_code(error error) noexcept
+{
+  return {static_cast<int>(error), error_category()};
+}
+
+namespace std
+{
+  template <> struct is_error_code_enum<error> : true_type
+  {
+  };
+}  // namespace std
+
+template <typename T> using enum_result = outcome::basic_result<T, error, outcome::policy::default_policy<T, error, void>>;
+
+enum_result<int> test()
+{
+  return 5;
+}
+
+outcome::std_result<int> abc()
+{
+  static_assert(std::is_error_code_enum<error>::value, "custom enum is not marked convertible to error code");
+  static_assert(std::is_constructible<boost::system::error_code, error>::value, "error code is not explicitly constructible from custom enum");
+  static_assert(std::is_convertible<error, boost::system::error_code>::value, "error code is not implicitly constructible from custom enum");
+  boost::system::error_code ec = error::test;  // custom enum is definitely convertible to error code
+  BOOST_OUTCOME_TRY(test());               // hence this should compile, as implicit conversions work here
+  (void) ec;
+
+  // But explicit conversions are required between dissimilar basic_result, implicit conversions are disabled
+  static_assert(std::is_constructible<outcome::std_result<int>, enum_result<int>>::value, "basic_result with error code is not explicitly constructible from basic_result with custom enum");
+  static_assert(!std::is_convertible<enum_result<int>, outcome::std_result<int>>::value, "basic_result with error code is implicitly constructible from basic_result with custom enum");
+  return 5;
+}
+
+BOOST_OUTCOME_AUTO_TEST_CASE(issues_0203_test, "enum convertible to error code works as designed")
+{
+  BOOST_CHECK(abc().value() == 5);
+}