From aecb8fe6dbc574dab746fccd6f14e055182c6953 Mon Sep 17 00:00:00 2001
From: Simon Brand <simon@codeplay.com>
Date: Mon, 3 Sep 2018 09:09:47 +0100
Subject: [PATCH] Fix #14

---
 CMakeLists.txt   |  1 +
 tests/issues.cpp | 19 +++++++++++++++++++
 tl/optional.hpp  |  6 +++---
 3 files changed, 23 insertions(+), 3 deletions(-)
 create mode 100644 tests/issues.cpp

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 9e28de6..63720f6 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -27,6 +27,7 @@ if(OPTIONAL_ENABLE_TESTS)
                    ${CMAKE_CURRENT_SOURCE_DIR}/tests/constexpr.cpp
                    ${CMAKE_CURRENT_SOURCE_DIR}/tests/constructors.cpp
                    ${CMAKE_CURRENT_SOURCE_DIR}/tests/assignment.cpp
+                   ${CMAKE_CURRENT_SOURCE_DIR}/tests/issues.cpp  
                    ${CMAKE_CURRENT_SOURCE_DIR}/tests/bases.cpp
                    ${CMAKE_CURRENT_SOURCE_DIR}/tests/nullopt.cpp)
 
diff --git a/tests/issues.cpp b/tests/issues.cpp
new file mode 100644
index 0000000..50211fe
--- /dev/null
+++ b/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));
+}
diff --git a/tl/optional.hpp b/tl/optional.hpp
index 3514d9e..53c5de0 100644
--- a/tl/optional.hpp
+++ b/tl/optional.hpp
@@ -1639,7 +1639,7 @@ template <class Opt, class F,
 constexpr auto optional_map_impl(Opt &&opt, F &&f) {
   return opt.has_value()
              ? detail::invoke(std::forward<F>(f), *std::forward<Opt>(opt))
-             : optional<detail::decay_t<Ret>>(nullopt);
+             : optional<Ret>(nullopt);
 }
 
 template <class Opt, class F,
@@ -1660,10 +1660,10 @@ template <class Opt, class F,
                                               *std::declval<Opt>())),
           detail::enable_if_t<!std::is_void<Ret>::value> * = nullptr>
 
-constexpr auto optional_map_impl(Opt &&opt, F &&f) -> optional<detail::decay_t<Ret>> {
+constexpr auto optional_map_impl(Opt &&opt, F &&f) -> optional<Ret> {
   return opt.has_value()
              ? detail::invoke(std::forward<F>(f), *std::forward<Opt>(opt))
-             : optional<detail::decay_t<Ret>>(nullopt);
+             : optional<Ret>(nullopt);
 }
 
 template <class Opt, class F,