Add preprocessor guards to disable extensions (TartanLlama#112)

CMakeLists.txt

@@ -17,6 +17,12 @@ endif()
 
 option(EXPECTED_BUILD_PACKAGE "Build package files as well" ON)
 
+option(EXPECTED_NO_EXT "Build with extensions disabled" OFF)
+
+if (EXPECTED_NO_EXT)
+    add_definitions(-DTL_EXPECTED_NO_EXT)
+endif()
+
 cmake_dependent_option(EXPECTED_BUILD_TESTS
   "Enable tl::expected tests" ON
   "BUILD_TESTING" OFF)
@@ -73,6 +79,11 @@ if(EXPECTED_BUILD_TESTS)
 
   file(GLOB test-sources CONFIGURE_DEPENDS tests/*.cpp)
   list(FILTER test-sources EXCLUDE REGEX "tests/test.cpp")
+
+  if (EXPECTED_NO_EXT)
+    list(FILTER test-sources EXCLUDE REGEX "tests/extensions.cpp")
+  endif()
+
   add_executable(${PROJECT_NAME}-tests "${test-sources}")
   target_compile_options(${PROJECT_NAME}-tests PRIVATE
     $<$<NOT:$<CXX_COMPILER_ID:MSVC>>:-Wall -Wextra>)

include/tl/expected.hpp

@@ -1251,6 +1251,7 @@ class expected : private detail::expected_move_assign_base<T, E>,
   typedef E error_type;
   typedef unexpected<E> unexpected_type;
 
+#ifndef TL_EXPECTED_NO_EXT
 #if defined(TL_EXPECTED_CXX14) && !defined(TL_EXPECTED_GCC49) &&               \
     !defined(TL_EXPECTED_GCC54) && !defined(TL_EXPECTED_GCC55)
   template <class F> TL_EXPECTED_11_CONSTEXPR auto and_then(F &&f) & {
@@ -1442,6 +1443,7 @@ class expected : private detail::expected_move_assign_base<T, E>,
   template <class F> expected constexpr or_else(F &&f) const && {
     return or_else_impl(std::move(*this), std::forward<F>(f));
   }
+#endif
 #endif
   constexpr expected() = default;
   constexpr expected(const expected &rhs) = default;
@@ -1942,6 +1944,7 @@ template <class Exp> using exp_t = typename detail::decay_t<Exp>::value_type;
 template <class Exp> using err_t = typename detail::decay_t<Exp>::error_type;
 template <class Exp, class Ret> using ret_t = expected<Ret, err_t<Exp>>;
 
+#ifndef TL_EXPECTED_NO_EXT
 #ifdef TL_EXPECTED_CXX14
 template <class Exp, class F,
           detail::enable_if_t<!std::is_void<exp_t<Exp>>::value> * = nullptr,
@@ -2260,6 +2263,7 @@ detail::decay_t<Exp> or_else_impl(Exp &&exp, F &&f) {
             std::forward<Exp>(exp));
 }
 #endif
+#endif
 } // namespace detail
 
 template <class T, class E, class U, class F>

tests/issues.cpp

@@ -5,6 +5,7 @@
 
 using std::string;
 
+#ifndef TL_EXPECTED_NO_EXT
 tl::expected<int, string> getInt3(int val) { return val; }
 
 tl::expected<int, string> getInt2(int val) { return val; }
@@ -22,6 +23,7 @@ TEST_CASE("Issue 17", "[issues.17]") {
 
   intermediate_result.and_then(operation2);
 }
+#endif
 
 struct a {};
 struct b : a {};
@@ -53,6 +55,7 @@ TEST_CASE("Issue 29", "[issues.29]") {
   REQUIRE(ov->size() == 1);
 }
 
+#ifndef TL_EXPECTED_NO_EXT
 tl::expected<int, std::string> error() {
   return tl::make_unexpected(std::string("error1 "));
 }
@@ -61,6 +64,7 @@ std::string maperror(std::string s) { return s + "maperror "; }
 TEST_CASE("Issue 30", "[issues.30]") {
   error().map_error(maperror);
 }
+#endif
 
 struct i31{
   int i;
@@ -74,14 +78,17 @@ TEST_CASE("Issue 31", "[issues.31]") {
     result2 = result;
 }
 
+#ifndef TL_EXPECTED_NO_EXT
 TEST_CASE("Issue 33", "[issues.33]") {
     tl::expected<void, int> res {tl::unexpect, 0};
     REQUIRE(!res);    
     res = res.map_error([](int i) { return 42; });
     REQUIRE(res.error() == 42);
 }
+#endif
 
 
+#ifndef TL_EXPECTED_NO_EXT
 tl::expected<void, std::string> voidWork() { return {}; }
 tl::expected<int, std::string> work2() { return 42; }
 void errorhandling(std::string){}
@@ -91,7 +98,9 @@ TEST_CASE("Issue 34", "[issues.34]") {
       .and_then (work2);
   result.map_error ([&] (std::string result) {errorhandling (result);});
 }
+#endif
 
+#ifndef TL_EXPECTED_NO_EXT
 struct non_copyable {
 	non_copyable(non_copyable&&) = default;
 	non_copyable(non_copyable const&) = delete;
@@ -101,12 +110,14 @@ struct non_copyable {
 TEST_CASE("Issue 42", "[issues.42]") {
 	tl::expected<non_copyable,int>{}.map([](non_copyable) {});
 }
+#endif
 
 TEST_CASE("Issue 43", "[issues.43]") {
 	auto result = tl::expected<void, std::string>{};
 	result = tl::make_unexpected(std::string{ "foo" });
 }
 
+#ifndef TL_EXPECTED_NO_EXT
 #if !(__GNUC__ <= 5)
 #include <memory>
 
@@ -127,6 +138,7 @@ TEST_CASE("Issue 49", "[issues.49]") {
     .and_then(test2);
 }
 #endif
+#endif
 
 tl::expected<int, std::unique_ptr<std::string>> func()
 {