Fix #14

tests/issues.cpp

@@ -0,0 +1,19 @@
+#include "catch.hpp"
+#include "optional.hpp"
+#include <type_traits>
+
+struct foo{
+    int& v() { return i; }
+    int i = 0;
+};
+
+int& x(int& i) { i = 42; return i;}
+
+TEST_CASE("issue 14") {
+    tl::optional<foo> f = foo{};
+    auto v = f.map(&foo::v).map(x);
+    static_assert(std::is_same<decltype(v), tl::optional<int&>>::value, "Must return a reference");
+    REQUIRE(f->i == 42);
+    REQUIRE(*v == 42);
+    REQUIRE((&f->i) == (&*v));
+}