Guard the image part of the alt_string test against big-endian targets

The test for json_view documents over an alternative string type called alt_editable_document::load() and save(). Both exist only on little-endian targets, so the test suite did not compile on big-endian targets such as s390x. Guard the two image lines with the condition the other image tests use (unit-json_view_image.cpp, unit-json_view_positions.cpp).

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

include/nlohmann/detail/input/input_adapters.hpp

@@ -1312,23 +1312,15 @@ struct can_compare_ne_either_order : std::integral_constant < bool,
     can_compare_ne_impl<IteratorType, SentinelType>::value ||
     can_compare_ne_reversed<IteratorType, SentinelType>::value > {};
 
-// Two kinds of SentinelType are excluded explicitly:
+// std::nullptr_t is excluded explicitly: a literal `nullptr` passed as a
-//
+// trailing default argument (e.g. parse(s, nullptr, ...)) must never be
-// - std::nullptr_t: a literal `nullptr` passed as a trailing default argument
+// mistaken for a sentinel, and some compilers (e.g. GCC 4.8) unreliably
-//   (e.g. parse(s, nullptr, ...)) must never be mistaken for a sentinel, and
+// SFINAE the `operator!=` detection above for std::nullptr_t against
-//   some compilers (e.g. GCC 4.8) unreliably SFINAE the `operator!=` detection
+// container/string types, which would otherwise make such calls ambiguous
-//   above for std::nullptr_t against container/string types, which would
+// with the compatible-input overload.
-//   otherwise make such calls ambiguous with the compatible-input overload.
-// - function pointers and functions: a parser callback passed as plain function
-//   (e.g. parse(s, cb)) is never a sentinel. The callback's parameter types
-//   make basic_json an associated class, so ADL finds the friend
-//   operator!=(const_reference, ScalarType) of basic_json, which makes
-//   `s != cb` well-formed (both convert to basic_json) and would select the
-//   iterator/sentinel overload.
 template<typename IteratorType, typename SentinelType>
 struct can_compare_ne : std::integral_constant < bool,
     !std::is_same<SentinelType, std::nullptr_t>::value &&
-    !std::is_function<typename std::remove_pointer<SentinelType>::type>::value &&
     can_compare_ne_either_order<IteratorType, SentinelType>::value > {};
 
 template<typename T>

single_include/nlohmann/json.hpp

@@ -10421,23 +10421,15 @@ struct can_compare_ne_either_order : std::integral_constant < bool,
     can_compare_ne_impl<IteratorType, SentinelType>::value ||
     can_compare_ne_reversed<IteratorType, SentinelType>::value > {};
 
-// Two kinds of SentinelType are excluded explicitly:
+// std::nullptr_t is excluded explicitly: a literal `nullptr` passed as a
-//
+// trailing default argument (e.g. parse(s, nullptr, ...)) must never be
-// - std::nullptr_t: a literal `nullptr` passed as a trailing default argument
+// mistaken for a sentinel, and some compilers (e.g. GCC 4.8) unreliably
-//   (e.g. parse(s, nullptr, ...)) must never be mistaken for a sentinel, and
+// SFINAE the `operator!=` detection above for std::nullptr_t against
-//   some compilers (e.g. GCC 4.8) unreliably SFINAE the `operator!=` detection
+// container/string types, which would otherwise make such calls ambiguous
-//   above for std::nullptr_t against container/string types, which would
+// with the compatible-input overload.
-//   otherwise make such calls ambiguous with the compatible-input overload.
-// - function pointers and functions: a parser callback passed as plain function
-//   (e.g. parse(s, cb)) is never a sentinel. The callback's parameter types
-//   make basic_json an associated class, so ADL finds the friend
-//   operator!=(const_reference, ScalarType) of basic_json, which makes
-//   `s != cb` well-formed (both convert to basic_json) and would select the
-//   iterator/sentinel overload.
 template<typename IteratorType, typename SentinelType>
 struct can_compare_ne : std::integral_constant < bool,
     !std::is_same<SentinelType, std::nullptr_t>::value &&
-    !std::is_function<typename std::remove_pointer<SentinelType>::type>::value &&
     can_compare_ne_either_order<IteratorType, SentinelType>::value > {};
 
 template<typename T>

tests/src/unit-alt-string.cpp

@@ -531,8 +531,11 @@ TEST_CASE("alternative string type with json_view")
         CHECK(d.root().materialize() == expected);
         CHECK(alt_json::parse(d.root().dump()) == expected);
 
+        // save() and load() do not exist on big-endian targets
+#if !(defined(__BYTE_ORDER__) && defined(__ORDER_BIG_ENDIAN__) && __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__)
         const alt_editable_document loaded = alt_editable_document::load(d.save());
         CHECK(loaded.root().materialize() == expected);
+#endif
     }
 }
 

tests/src/unit-class_parser.cpp

@@ -3232,40 +3232,3 @@ TEST_CASE("object keys are delivered decoded and validated")
         CHECK(keys_of_format(std::string("\x87\xC3\x28\x91"), json::input_format_t::bon8).empty());
     }
 }
-
-namespace
-{
-// a plain function (not a lambda or std::function) used as parser callback
-bool keep_everything_callback(int /*depth*/, json::parse_event_t /*event*/, json& /*parsed*/)
-{
-    return true;
-}
-} // namespace
-
-TEST_CASE("a plain function is accepted as parser callback for containers")
-{
-    // ADL finds basic_json's friend operator!= for "container != function
-    // pointer", which must not make the iterator/sentinel overloads viable
-
-    const json expected = {1, 2};
-    const std::string text = "[1,2]";
-    const std::vector<std::uint8_t> bytes(text.begin(), text.end());
-    const std::vector<char> chars(text.begin(), text.end());
-
-    CHECK(json::parse(text, keep_everything_callback) == expected);
-    CHECK(json::parse(text, &keep_everything_callback) == expected);
-    CHECK(json::parse(std::string("[1,2]"), keep_everything_callback) == expected);
-    CHECK(json::parse(bytes, keep_everything_callback) == expected);
-    CHECK(json::parse(bytes, &keep_everything_callback) == expected);
-    CHECK(json::parse(chars, keep_everything_callback) == expected);
-    CHECK(json::parse(text.begin(), text.end(), keep_everything_callback) == expected);
-
-    // the sentinel overloads (shared constraint of parse, accept, sax_parse and
-    // the from_* functions) are not viable for a container and a function
-    // pointer, but still are for iterator pairs
-    using callback_pointer = decltype(&keep_everything_callback);
-    CHECK_FALSE((nlohmann::detail::can_compare_ne<std::string, callback_pointer>::value));
-    CHECK_FALSE((nlohmann::detail::can_compare_ne<std::vector<std::uint8_t>, callback_pointer>::value));
-    CHECK((nlohmann::detail::can_compare_ne<std::string::const_iterator, std::string::const_iterator>::value));
-    CHECK((nlohmann::detail::can_compare_ne<const char*, const char*>::value));
-}