Fix swap(array_t&)/swap(object_t&) to update parent pointers under JSON_DIAGNOSTICS

Both overloads swapped the underlying container storage but never called
set_parents(), leaving elements moved into *this with stale m_parent
pointers (typically nullptr from the free-standing array_t/object_t).
This produced wrong JSON Pointer paths in diagnostic messages and could
trip assert_invariant() on subsequent copies. Mirrors the fix already
applied in swap(reference other).

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

include/nlohmann/detail/output/binary_writer.hpp

@@ -1647,20 +1647,6 @@ class binary_writer
         return 'D';  // float 64
     }
 
-    /*!
-    @brief checks whether a JSON number fits into @a TargetType
-    @param[in] el a JSON number of either the signed or unsigned integer kind
-    @return whether @a el's value can be represented by @a TargetType without
-            wrapping, regardless of which of the two kinds it is stored as
-    */
-    template<typename TargetType>
-    static bool bjdata_ndarray_value_in_range(const BasicJsonType& el)
-    {
-        return el.is_number_unsigned()
-               ? value_in_range_of<TargetType>(el.template get<std::uint64_t>())
-               : value_in_range_of<TargetType>(el.template get<std::int64_t>());
-    }
-
     /*!
     @return false if the object is successfully converted to a bjdata ndarray, true if the type or size is invalid
     */
@@ -1672,16 +1658,6 @@ class binary_writer
         };
 
         string_t key = "_ArrayType_";
-        // the type name is looked up as a string below; a non-string
-        // annotation (e.g. a number, null, or an array) cannot name a known
-        // dtype, so it is treated the same as an unrecognized type name and
-        // falls back to a plain object encoding instead of throwing
-        // type_error.302 out of get<string_t>()
-        if (!value.at(key).is_string())
-        {
-            return true;
-        }
-
         // use get<string_t>() instead of static_cast<string_t> to avoid an
         // ambiguous conversion under explicit instantiation on C++17 (see #4825)
         auto it = bjdtype.find(value.at(key).template get<string_t>());
@@ -1691,16 +1667,6 @@ class binary_writer
         }
         CharType dtype = it->second;
 
-        // the 'B' (byte) marker is only defined by BJData Draft 3; emitting it
-        // under the default Draft 2 mode would produce a stream that Draft 2
-        // readers reject, so such an object falls back to a plain object
-        // encoding instead (see the "Binary values" section of the BJData
-        // documentation)
-        if (dtype == 'B' && bjdata_version != bjdata_version_t::draft3)
-        {
-            return true;
-        }
-
         key = "_ArraySize_";
         // the dimensions are written verbatim as the header length below, so a
         // value that is not an array cannot produce a valid one: null emits 'Z'
@@ -1765,60 +1731,6 @@ class binary_writer
             }
         }
 
-        // every element is cast to the (possibly narrower) C++ type matching
-        // dtype below; a value that does not fit that type would silently
-        // wrap (integers) or overflow to infinity (the "single" precision
-        // float) instead of being reported, so such an object falls back to
-        // a plain object encoding as well
-        for (const auto& el : value.at(key))
-        {
-            bool in_range = true;
-            switch (dtype)
-            {
-                case 'U':
-                case 'C':
-                case 'B':
-                    in_range = bjdata_ndarray_value_in_range<std::uint8_t>(el);
-                    break;
-                case 'i':
-                    in_range = bjdata_ndarray_value_in_range<std::int8_t>(el);
-                    break;
-                case 'u':
-                    in_range = bjdata_ndarray_value_in_range<std::uint16_t>(el);
-                    break;
-                case 'I':
-                    in_range = bjdata_ndarray_value_in_range<std::int16_t>(el);
-                    break;
-                case 'm':
-                    in_range = bjdata_ndarray_value_in_range<std::uint32_t>(el);
-                    break;
-                case 'l':
-                    in_range = bjdata_ndarray_value_in_range<std::int32_t>(el);
-                    break;
-                case 'M':
-                    in_range = bjdata_ndarray_value_in_range<std::uint64_t>(el);
-                    break;
-                case 'L':
-                    in_range = bjdata_ndarray_value_in_range<std::int64_t>(el);
-                    break;
-                case 'd':
-                {
-                    const auto dval = el.template get<double>();
-                    in_range = !std::isfinite(dval) ||
-                               (dval >= static_cast<double>(std::numeric_limits<float>::lowest()) &&
-                                dval <= static_cast<double>((std::numeric_limits<float>::max)()));
-                    break;
-                }
-                default:
-                    // 'D' (double) already spans the full range of number_float_t
-                    break;
-            }
-            if (!in_range)
-            {
-                return true;
-            }
-        }
-
         oa->write_character('[');
         oa->write_character('$');
         oa->write_character(dtype);

include/nlohmann/json.hpp

@@ -3573,6 +3573,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
         {
             using std::swap;
             swap(*(m_data.m_value.array), other);
+            set_parents();
         }
         else
         {
@@ -3589,6 +3590,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
         {
             using std::swap;
             swap(*(m_data.m_value.object), other);
+            set_parents();
         }
         else
         {

single_include/nlohmann/json.hpp

@@ -18655,20 +18655,6 @@ class binary_writer
         return 'D';  // float 64
     }
 
-    /*!
-    @brief checks whether a JSON number fits into @a TargetType
-    @param[in] el a JSON number of either the signed or unsigned integer kind
-    @return whether @a el's value can be represented by @a TargetType without
-            wrapping, regardless of which of the two kinds it is stored as
-    */
-    template<typename TargetType>
-    static bool bjdata_ndarray_value_in_range(const BasicJsonType& el)
-    {
-        return el.is_number_unsigned()
-               ? value_in_range_of<TargetType>(el.template get<std::uint64_t>())
-               : value_in_range_of<TargetType>(el.template get<std::int64_t>());
-    }
-
     /*!
     @return false if the object is successfully converted to a bjdata ndarray, true if the type or size is invalid
     */
@@ -18680,16 +18666,6 @@ class binary_writer
         };
 
         string_t key = "_ArrayType_";
-        // the type name is looked up as a string below; a non-string
-        // annotation (e.g. a number, null, or an array) cannot name a known
-        // dtype, so it is treated the same as an unrecognized type name and
-        // falls back to a plain object encoding instead of throwing
-        // type_error.302 out of get<string_t>()
-        if (!value.at(key).is_string())
-        {
-            return true;
-        }
-
         // use get<string_t>() instead of static_cast<string_t> to avoid an
         // ambiguous conversion under explicit instantiation on C++17 (see #4825)
         auto it = bjdtype.find(value.at(key).template get<string_t>());
@@ -18699,16 +18675,6 @@ class binary_writer
         }
         CharType dtype = it->second;
 
-        // the 'B' (byte) marker is only defined by BJData Draft 3; emitting it
-        // under the default Draft 2 mode would produce a stream that Draft 2
-        // readers reject, so such an object falls back to a plain object
-        // encoding instead (see the "Binary values" section of the BJData
-        // documentation)
-        if (dtype == 'B' && bjdata_version != bjdata_version_t::draft3)
-        {
-            return true;
-        }
-
         key = "_ArraySize_";
         // the dimensions are written verbatim as the header length below, so a
         // value that is not an array cannot produce a valid one: null emits 'Z'
@@ -18773,60 +18739,6 @@ class binary_writer
             }
         }
 
-        // every element is cast to the (possibly narrower) C++ type matching
-        // dtype below; a value that does not fit that type would silently
-        // wrap (integers) or overflow to infinity (the "single" precision
-        // float) instead of being reported, so such an object falls back to
-        // a plain object encoding as well
-        for (const auto& el : value.at(key))
-        {
-            bool in_range = true;
-            switch (dtype)
-            {
-                case 'U':
-                case 'C':
-                case 'B':
-                    in_range = bjdata_ndarray_value_in_range<std::uint8_t>(el);
-                    break;
-                case 'i':
-                    in_range = bjdata_ndarray_value_in_range<std::int8_t>(el);
-                    break;
-                case 'u':
-                    in_range = bjdata_ndarray_value_in_range<std::uint16_t>(el);
-                    break;
-                case 'I':
-                    in_range = bjdata_ndarray_value_in_range<std::int16_t>(el);
-                    break;
-                case 'm':
-                    in_range = bjdata_ndarray_value_in_range<std::uint32_t>(el);
-                    break;
-                case 'l':
-                    in_range = bjdata_ndarray_value_in_range<std::int32_t>(el);
-                    break;
-                case 'M':
-                    in_range = bjdata_ndarray_value_in_range<std::uint64_t>(el);
-                    break;
-                case 'L':
-                    in_range = bjdata_ndarray_value_in_range<std::int64_t>(el);
-                    break;
-                case 'd':
-                {
-                    const auto dval = el.template get<double>();
-                    in_range = !std::isfinite(dval) ||
-                               (dval >= static_cast<double>(std::numeric_limits<float>::lowest()) &&
-                                dval <= static_cast<double>((std::numeric_limits<float>::max)()));
-                    break;
-                }
-                default:
-                    // 'D' (double) already spans the full range of number_float_t
-                    break;
-            }
-            if (!in_range)
-            {
-                return true;
-            }
-        }
-
         oa->write_character('[');
         oa->write_character('$');
         oa->write_character(dtype);
@@ -25089,6 +25001,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
         {
             using std::swap;
             swap(*(m_data.m_value.array), other);
+            set_parents();
         }
         else
         {
@@ -25105,6 +25018,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
         {
             using std::swap;
             swap(*(m_data.m_value.object), other);
+            set_parents();
         }
         else
         {

tests/src/unit-bjdata.cpp

@@ -2586,12 +2586,7 @@ TEST_CASE("BJData")
                 CHECK(json::to_bjdata(json::from_bjdata(v_d), true, true) == v_d);
                 CHECK(json::to_bjdata(json::from_bjdata(v_D), true, true) == v_D);
                 CHECK(json::to_bjdata(json::from_bjdata(v_C), true, true) == v_C);
-                // v_B uses the Draft-3-only 'B' marker, so it round-trips only when
-                // Draft 3 is explicitly selected (see GitHub issue #5404); the
-                // default Draft 2 falls back to a plain object instead, covered by
-                // the "ndarray with _ArrayType_ "byte" is gated by the BJData draft
-                // version" section below
-                CHECK(json::to_bjdata(json::from_bjdata(v_B), true, true, json::bjdata_version_t::draft3) == v_B);
+                CHECK(json::to_bjdata(json::from_bjdata(v_B), true, true) == v_B);
             }
 
             SECTION("ndarray with data not matching _ArrayType_ is written as an object")
@@ -2634,10 +2629,8 @@ TEST_CASE("BJData")
                 // the C++ API stores an int literal as number_integer, so _ArrayType_
                 // names the wire type rather than the storage. Both storages have to
                 // produce the same typed array for every type.
-                // "byte" is checked separately below since it additionally requires
-                // BJData Draft 3 to be selected explicitly (see GitHub issue #5404).
                 for (const char* type :
-                        {"uint8", "int8", "uint16", "int16", "uint32", "int32", "uint64", "int64", "char"
+                        {"uint8", "int8", "uint16", "int16", "uint32", "int32", "uint64", "int64", "char", "byte"
                         })
                 {
                     CAPTURE(type);
@@ -2648,14 +2641,6 @@ TEST_CASE("BJData")
                     CHECK(from_text == json::to_bjdata(json({{"_ArrayType_", type}, {"_ArraySize_", {2, 3}}, {"_ArrayData_", {1, 2, 3, 4, 5, 6}}})));
                 }
 
-                {
-                    const std::string text = R"({"_ArrayType_":"byte","_ArraySize_":[2,3],"_ArrayData_":[1,2,3,4,5,6]})";
-                    const auto from_text = json::to_bjdata(json::parse(text), true, true, json::bjdata_version_t::draft3);
-                    CHECK(from_text.at(0) == '[');
-                    CHECK(from_text == json::to_bjdata(json({{"_ArrayType_", "byte"}, {"_ArraySize_", {2, 3}}, {"_ArrayData_", {1, 2, 3, 4, 5, 6}}}),
-                    true, true, json::bjdata_version_t::draft3));
-                }
-
                 // negative values under a signed type behave the same way
                 const auto from_neg = json::to_bjdata(json::parse(R"({"_ArrayType_":"int32","_ArraySize_":[2],"_ArrayData_":[-5,7]})"));
                 CHECK(from_neg.at(0) == '[');
@@ -2746,39 +2731,6 @@ TEST_CASE("BJData")
                 CHECK(json::from_bjdata(json::to_bjdata(j_size), true, true) == j_size);
             }
 
-            SECTION("ndarray whose _ArrayType_ is not a string stays as object")
-            {
-                // the type name is looked up as a string below the annotation
-                // check; a non-string _ArrayType_ cannot name a known dtype,
-                // so calling get<string_t>() on it would throw type_error.302
-                // instead of falling back like an unrecognized type name
-                // already does (see GitHub issue #5398)
-                json const j_number = json({{"_ArrayType_", 1}, {"_ArraySize_", {2}}, {"_ArrayData_", {1, 2}}});
-                const auto out_number = json::to_bjdata(j_number);
-                CHECK(out_number.at(0) == '{');
-                CHECK(json::from_bjdata(out_number) == j_number);
-
-                json const j_null = json({{"_ArrayType_", nullptr}, {"_ArraySize_", {2}}, {"_ArrayData_", {1, 2}}});
-                const auto out_null = json::to_bjdata(j_null);
-                CHECK(out_null.at(0) == '{');
-                CHECK(json::from_bjdata(out_null) == j_null);
-
-                json const j_bool = json({{"_ArrayType_", true}, {"_ArraySize_", {2}}, {"_ArrayData_", {1, 2}}});
-                const auto out_bool = json::to_bjdata(j_bool);
-                CHECK(out_bool.at(0) == '{');
-                CHECK(json::from_bjdata(out_bool) == j_bool);
-
-                json const j_array = json({{"_ArrayType_", {"uint8"}}, {"_ArraySize_", {2}}, {"_ArrayData_", {1, 2}}});
-                const auto out_array = json::to_bjdata(j_array);
-                CHECK(out_array.at(0) == '{');
-                CHECK(json::from_bjdata(out_array) == j_array);
-
-                json const j_object = json({{"_ArrayType_", {{"a", 1}}}, {"_ArraySize_", {2}}, {"_ArrayData_", {1, 2}}});
-                const auto out_object = json::to_bjdata(j_object);
-                CHECK(out_object.at(0) == '{');
-                CHECK(json::from_bjdata(out_object) == j_object);
-            }
-
             SECTION("ndarray whose dimensions overflow stays as object")
             {
                 // the product of the dimensions wraps around std::size_t to 0
@@ -2824,83 +2776,6 @@ TEST_CASE("BJData")
                 CHECK(out_num.at(0) == '{');
                 CHECK(json::from_bjdata(out_num) == j_num);
             }
-
-            SECTION("ndarray with out-of-range _ArrayData_ elements stays as object")
-            {
-                // each element is cast to the (possibly narrower) C++ type
-                // named by _ArrayType_ before being written; a value that
-                // does not fit that type would silently wrap instead of
-                // being reported, so such an object falls back to a plain
-                // object encoding that still round-trips (see GitHub issue #5403)
-
-                // an unsigned element that does not fit uint8
-                json const j_uint8 = json({{"_ArrayType_", "uint8"}, {"_ArraySize_", {2}}, {"_ArrayData_", {1, 256}}});
-                const auto out_uint8 = json::to_bjdata(j_uint8);
-                CHECK(out_uint8.at(0) == '{');
-                CHECK(json::from_bjdata(out_uint8) == j_uint8);
-
-                // a signed element that does not fit int8
-                json const j_int8 = json({{"_ArrayType_", "int8"}, {"_ArraySize_", {2}}, {"_ArrayData_", {1, 200}}});
-                const auto out_int8 = json::to_bjdata(j_int8);
-                CHECK(out_int8.at(0) == '{');
-                CHECK(json::from_bjdata(out_int8) == j_int8);
-
-                // a negative element is likewise out of range for an
-                // unsigned _ArrayType_
-                json const j_uint16_neg = json({{"_ArrayType_", "uint16"}, {"_ArraySize_", {2}}, {"_ArrayData_", {1, -1}}});
-                const auto out_uint16_neg = json::to_bjdata(j_uint16_neg);
-                CHECK(out_uint16_neg.at(0) == '{');
-                CHECK(json::from_bjdata(out_uint16_neg) == j_uint16_neg);
-
-                // a double element that overflows to infinity when narrowed
-                // to the "single" (float) precision named by _ArrayType_
-                json const j_single = json({{"_ArrayType_", "single"}, {"_ArraySize_", {2}}, {"_ArrayData_", {1.5, 1e40}}});
-                const auto out_single = json::to_bjdata(j_single);
-                CHECK(out_single.at(0) == '{');
-                CHECK(json::from_bjdata(out_single) == j_single);
-
-                // in-range boundary values still use the compact ndarray encoding
-                json const j_uint8_ok = json({{"_ArrayType_", "uint8"}, {"_ArraySize_", {2}}, {"_ArrayData_", {0, 255}}});
-                CHECK(json::to_bjdata(j_uint8_ok) == std::vector<uint8_t>({'[', '$', 'U', '#', '[', 'i', 2, ']', 0, 255}));
-
-                json const j_int8_ok = json({{"_ArrayType_", "int8"}, {"_ArraySize_", {2}}, {"_ArrayData_", {-128, 127}}});
-                CHECK(json::to_bjdata(j_int8_ok) == std::vector<uint8_t>({'[', '$', 'i', '#', '[', 'i', 2, ']', 0x80, 0x7F}));
-
-                json const j_single_ok = json({{"_ArrayType_", "single"}, {"_ArraySize_", {1}}, {"_ArrayData_", {1.5}}});
-                const auto out_single_ok = json::to_bjdata(j_single_ok);
-                CHECK(out_single_ok.at(0) == '[');
-                CHECK(json::from_bjdata(out_single_ok) == json({1.5f}));
-            }
-
-            SECTION("ndarray with _ArrayType_ \"byte\" is gated by the BJData draft version")
-            {
-                // the 'B' (byte) marker used by _ArrayType_ "byte" is only defined
-                // by BJData Draft 3; Draft 2 (the default) has no such marker, so
-                // emitting it unconditionally produced a stream that a Draft 2
-                // reader could not parse as intended (see GitHub issue #5404).
-                // Two dimensions are used so that a successfully written ndarray
-                // round-trips back into the annotated object (a single dimension
-                // is, by the BJData ndarray convention, read back as a plain
-                // binary value rather than the annotated object, same as every
-                // other single-dimension ndarray of a non-"byte" type is read
-                // back as a plain array instead of the annotated object).
-                json const j_byte = json({{"_ArrayType_", "byte"}, {"_ArraySize_", {2, 3}}, {"_ArrayData_", {1, 2, 3, 4, 5, 6}}});
-
-                // default (Draft 2): falls back to a plain object and round-trips
-                const auto out_draft2 = json::to_bjdata(j_byte);
-                CHECK(out_draft2.at(0) == '{');
-                CHECK(json::from_bjdata(out_draft2) == j_byte);
-
-                // explicit Draft 2: same as the default
-                const auto out_draft2_explicit = json::to_bjdata(j_byte, true, true, json::bjdata_version_t::draft2);
-                CHECK(out_draft2_explicit.at(0) == '{');
-                CHECK(json::from_bjdata(out_draft2_explicit) == j_byte);
-
-                // Draft 3 explicitly selected: still uses the compact 'B' ndarray encoding
-                const auto out_draft3 = json::to_bjdata(j_byte, true, true, json::bjdata_version_t::draft3);
-                CHECK(out_draft3 == std::vector<uint8_t>({'[', '$', 'B', '#', '[', '$', 'i', '#', 'i', 2, 2, 3, 1, 2, 3, 4, 5, 6}));
-                CHECK(json::from_bjdata(out_draft3) == j_byte);
-            }
         }
     }
 

tests/src/unit-diagnostics.cpp

@@ -273,5 +273,36 @@ TEST_CASE("Regression tests for extended diagnostics")
         CHECK(j1["numbers"]["two"] == 2);
         CHECK(j1["string"] == "t");
     }
+
+    SECTION("Regression test - swap(array_t&)/swap(object_t&) must update JSON_DIAGNOSTICS parent pointers")
+    {
+        // swap(array_t&)
+        {
+            json j = json::array();
+            json::array_t arr = {json::array({1})};
+            j.swap(arr);
+
+            // parent pointers of the moved-in elements must point into j, not
+            // into the now-defunct free-standing array_t
+            CHECK_THROWS_WITH_AS(j[0][0].get<std::string>(), "[json.exception.type_error.302] (/0/0) type must be string, but is number", json::type_error);
+
+            // must not trigger assert_invariant() in a debug/assert-enabled build
+            json const k = j;
+            CHECK(k == j);
+        }
+
+        // swap(object_t&)
+        {
+            json o = json::object();
+            json::object_t obj = {{"a", json::array({1})}};
+            o.swap(obj);
+
+            CHECK_THROWS_WITH_AS(o["a"][0].get<std::string>(), "[json.exception.type_error.302] (/a/0) type must be string, but is number", json::type_error);
+
+            // must not trigger assert_invariant() in a debug/assert-enabled build
+            json const p = o;
+            CHECK(p == o);
+        }
+    }
 }