Move custom object key tests out of unit-cbor.cpp and unit-msgpack.cpp (#5798)

The custom object key tests from #5328 instantiate a second basic_json
specialization in unit-cbor.cpp and unit-msgpack.cpp. This pushed
unit-msgpack.cpp.obj past 65535 sections in the clang (MinGW) jobs of
the Windows workflow, and linking test-msgpack_cpp11 fails with
"relocation truncated to fit: IMAGE_REL_AMD64_REL32 against `.rdata'".

The GNU linker keeps the section an associative COMDAT section belongs
to in 16 bits (x_associated in include/coff/internal.h), although big
object files store 32 bits. In larger objects it therefore ties the
jump tables of inline functions to the wrong function and discards them
together with that function's duplicate.

Move the four tests unchanged into unit-custom-object-key-type.cpp and
document the limit in windows.yml.

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

tests/src/unit-cbor.cpp

@@ -28,7 +28,6 @@ using nlohmann::json;
 #include "make_test_data_available.hpp"
 #include "round_trip_corpus.hpp"
 #include "test_utils.hpp"
-#include "custom_object_key_type.hpp"
 #include "sax_countdown.hpp"
 using utils::SaxCountdown;
 
@@ -3358,55 +3357,3 @@ TEST_CASE("CBOR large strings and binaries (chunked reader)")
         }
     }
 }
-
-TEST_CASE("CBOR supports custom object key types")
-{
-    using custom_json = custom_object_key_test::json;
-    using custom_key = custom_object_key_test::key;
-
-    custom_json::object_t object;
-    object.emplace(custom_key{"short"}, 1);
-    object.emplace(
-              custom_key{"a key longer than twenty-three characters"},
-              2);
-
-    const custom_json value(std::move(object));
-    const auto encoded = custom_json::to_cbor(value);
-
-    CHECK(nlohmann::json::from_cbor(encoded) == nlohmann::json
-    {
-        {"short", 1},
-        {"a key longer than twenty-three characters", 2}
-    });
-}
-
-TEST_CASE("CBOR supports custom object key types nested deeper than the recursion depth limit")
-{
-    // below detail::recursion_depth_limit(), keys are written by
-    // write_cbor_iterative instead of write_cbor
-    using custom_json = custom_object_key_test::json;
-    using custom_key = custom_object_key_test::key;
-
-    const std::size_t depth = nlohmann::detail::recursion_depth_limit() + 10;
-
-    custom_json value = 1;
-    nlohmann::json expected = 1;
-    for (std::size_t i = 0; i < depth; ++i)
-    {
-        // alternate short keys with ones long enough to need a length byte
-        const std::string name = (i % 2 == 0) ? "k" + std::to_string(i)
-                                 : "a key longer than thirty-one characters " + std::to_string(i);
-
-        custom_json::object_t object;
-        object.emplace(custom_key{name}, std::move(value));
-        value = custom_json(std::move(object));
-
-        nlohmann::json::object_t expected_object;
-        expected_object.emplace(name, std::move(expected));
-        expected = nlohmann::json(std::move(expected_object));
-    }
-
-    const auto encoded = custom_json::to_cbor(value);
-    CHECK(encoded == nlohmann::json::to_cbor(expected));
-    CHECK(nlohmann::json::from_cbor(encoded) == expected);
-}

tests/src/unit-custom-object-key-type.cpp

@@ -0,0 +1,127 @@
+//     __ _____ _____ _____
+//  __|  |   __|     |   | |  JSON for Modern C++ (supporting code)
+// |  |  |__   |  |  | | | |  version 3.12.0
+// |_____|_____|_____|_|___|  https://github.com/nlohmann/json
+//
+// SPDX-FileCopyrightText: 2013-2026 Niels Lohmann <https://nlohmann.me>
+// SPDX-License-Identifier: MIT
+
+#include "doctest_compatibility.h"
+
+#include <nlohmann/json.hpp>
+
+#include <cstddef>
+#include <string>
+#include <utility>
+
+#include "custom_object_key_type.hpp"
+
+// These tests instantiate a second basic_json specialization. They live in
+// their own file rather than in unit-cbor.cpp and unit-msgpack.cpp to keep
+// those objects below 65535 sections: the MinGW linker stores the section a
+// COMDAT section is associated with in 16 bits, so it misplaces the jump
+// tables of larger objects (see the clang job in windows.yml).
+
+TEST_CASE("CBOR supports custom object key types")
+{
+    using custom_json = custom_object_key_test::json;
+    using custom_key = custom_object_key_test::key;
+
+    custom_json::object_t object;
+    object.emplace(custom_key{"short"}, 1);
+    object.emplace(
+              custom_key{"a key longer than twenty-three characters"},
+              2);
+
+    const custom_json value(std::move(object));
+    const auto encoded = custom_json::to_cbor(value);
+
+    CHECK(nlohmann::json::from_cbor(encoded) == nlohmann::json
+    {
+        {"short", 1},
+        {"a key longer than twenty-three characters", 2}
+    });
+}
+
+TEST_CASE("CBOR supports custom object key types nested deeper than the recursion depth limit")
+{
+    // below detail::recursion_depth_limit(), keys are written by
+    // write_cbor_iterative instead of write_cbor
+    using custom_json = custom_object_key_test::json;
+    using custom_key = custom_object_key_test::key;
+
+    const std::size_t depth = nlohmann::detail::recursion_depth_limit() + 10;
+
+    custom_json value = 1;
+    nlohmann::json expected = 1;
+    for (std::size_t i = 0; i < depth; ++i)
+    {
+        // alternate short keys with ones long enough to need a length byte
+        const std::string name = (i % 2 == 0) ? "k" + std::to_string(i)
+                                 : "a key longer than thirty-one characters " + std::to_string(i);
+
+        custom_json::object_t object;
+        object.emplace(custom_key{name}, std::move(value));
+        value = custom_json(std::move(object));
+
+        nlohmann::json::object_t expected_object;
+        expected_object.emplace(name, std::move(expected));
+        expected = nlohmann::json(std::move(expected_object));
+    }
+
+    const auto encoded = custom_json::to_cbor(value);
+    CHECK(encoded == nlohmann::json::to_cbor(expected));
+    CHECK(nlohmann::json::from_cbor(encoded) == expected);
+}
+
+TEST_CASE("MessagePack supports custom object key types")
+{
+    using custom_json = custom_object_key_test::json;
+    using custom_key = custom_object_key_test::key;
+
+    custom_json::object_t object;
+    object.emplace(custom_key{"short"}, 1);
+    object.emplace(
+              custom_key{"a key longer than thirty-one characters"},
+              2);
+
+    const custom_json value(std::move(object));
+    const auto encoded = custom_json::to_msgpack(value);
+
+    CHECK(nlohmann::json::from_msgpack(encoded) == nlohmann::json
+    {
+        {"short", 1},
+        {"a key longer than thirty-one characters", 2}
+    });
+}
+
+TEST_CASE("MessagePack supports custom object key types nested deeper than the recursion depth limit")
+{
+    // below detail::recursion_depth_limit(), keys are written by
+    // write_msgpack_iterative instead of write_msgpack
+    using custom_json = custom_object_key_test::json;
+    using custom_key = custom_object_key_test::key;
+
+    const std::size_t depth = nlohmann::detail::recursion_depth_limit() + 10;
+
+    custom_json value = 1;
+    nlohmann::json expected = 1;
+    for (std::size_t i = 0; i < depth; ++i)
+    {
+        // alternate short keys with ones long enough to need a length byte
+        const std::string name = (i % 2 == 0) ? "k" + std::to_string(i)
+                                 : "a key longer than thirty-one characters " + std::to_string(i);
+
+        custom_json::object_t object;
+        object.emplace(custom_key{name}, std::move(value));
+        value = custom_json(std::move(object));
+
+        nlohmann::json::object_t expected_object;
+        expected_object.emplace(name, std::move(expected));
+        expected = nlohmann::json(std::move(expected_object));
+    }
+
+    const auto encoded = custom_json::to_msgpack(value);
+    CHECK(encoded == nlohmann::json::to_msgpack(expected));
+    CHECK(nlohmann::json::from_msgpack(encoded) == expected);
+}

tests/src/unit-msgpack.cpp

@@ -31,7 +31,6 @@ using nlohmann::json;
 #include "make_test_data_available.hpp"
 #include "round_trip_corpus.hpp"
 #include "test_utils.hpp"
-#include "custom_object_key_type.hpp"
 #include "sax_countdown.hpp"
 using utils::SaxCountdown;
 
@@ -2483,55 +2482,3 @@ TEST_CASE("MessagePack large strings and binaries (chunked reader)")
         }
     }
 }
-
-TEST_CASE("MessagePack supports custom object key types")
-{
-    using custom_json = custom_object_key_test::json;
-    using custom_key = custom_object_key_test::key;
-
-    custom_json::object_t object;
-    object.emplace(custom_key{"short"}, 1);
-    object.emplace(
-              custom_key{"a key longer than thirty-one characters"},
-              2);
-
-    const custom_json value(std::move(object));
-    const auto encoded = custom_json::to_msgpack(value);
-
-    CHECK(nlohmann::json::from_msgpack(encoded) == nlohmann::json
-    {
-        {"short", 1},
-        {"a key longer than thirty-one characters", 2}
-    });
-}
-
-TEST_CASE("MessagePack supports custom object key types nested deeper than the recursion depth limit")
-{
-    // below detail::recursion_depth_limit(), keys are written by
-    // write_msgpack_iterative instead of write_msgpack
-    using custom_json = custom_object_key_test::json;
-    using custom_key = custom_object_key_test::key;
-
-    const std::size_t depth = nlohmann::detail::recursion_depth_limit() + 10;
-
-    custom_json value = 1;
-    nlohmann::json expected = 1;
-    for (std::size_t i = 0; i < depth; ++i)
-    {
-        // alternate short keys with ones long enough to need a length byte
-        const std::string name = (i % 2 == 0) ? "k" + std::to_string(i)
-                                 : "a key longer than thirty-one characters " + std::to_string(i);
-
-        custom_json::object_t object;
-        object.emplace(custom_key{name}, std::move(value));
-        value = custom_json(std::move(object));
-
-        nlohmann::json::object_t expected_object;
-        expected_object.emplace(name, std::move(expected));
-        expected = nlohmann::json(std::move(expected_object));
-    }
-
-    const auto encoded = custom_json::to_msgpack(value);
-    CHECK(encoded == nlohmann::json::to_msgpack(expected));
-    CHECK(nlohmann::json::from_msgpack(encoded) == expected);
-}