Fall back to plain-object encoding when _ArrayType_ is not a string

write_bjdata_ndarray() looked up _ArrayType_ by calling get<string_t>()
directly, which throws type_error.302 when the annotation is not a
string (e.g. a number, null, boolean, array, or object). Per the
documented BJData ndarray contract, an object only qualifies for the
compact ndarray encoding if _ArrayType_ names a known type; anything
else must fall back to plain-object encoding, the same way an unknown
type-name string already does.

Add an is_string() check before the get<string_t>() call so a
non-string _ArrayType_ takes the existing "unrecognized type name"
fallback path instead of throwing.

Fixes #5398.

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

include/nlohmann/detail/output/binary_writer.hpp

@@ -1647,6 +1647,20 @@ 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
     */
@@ -1658,6 +1672,16 @@ 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>());
@@ -1667,6 +1691,16 @@ 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'
@@ -1731,6 +1765,60 @@ 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/detail/output/serializer.hpp

@@ -71,7 +71,7 @@ class serializer
         , thousands_sep(loc->thousands_sep == nullptr ? '\0' : std::char_traits<char>::to_char_type(* (loc->thousands_sep)))
         , decimal_point(loc->decimal_point == nullptr ? '\0' : std::char_traits<char>::to_char_type(* (loc->decimal_point)))
         , indent_char(ichar)
-        , indent_string()
+        , indent_string(512, indent_char)
         , error_handler(error_handler_)
     {}
 
@@ -126,10 +126,6 @@ class serializer
 
                     // variable to hold indentation for recursive calls
                     const auto new_indent = current_indent + indent_step;
-                    if (JSON_HEDLEY_UNLIKELY(indent_string.empty()))
-                    {
-                        indent_string.resize(512, indent_char);
-                    }
                     if (JSON_HEDLEY_UNLIKELY(indent_string.size() < new_indent))
                     {
                         indent_string.resize(indent_string.size() * 2, ' ');
@@ -203,10 +199,6 @@ class serializer
 
                     // variable to hold indentation for recursive calls
                     const auto new_indent = current_indent + indent_step;
-                    if (JSON_HEDLEY_UNLIKELY(indent_string.empty()))
-                    {
-                        indent_string.resize(512, indent_char);
-                    }
                     if (JSON_HEDLEY_UNLIKELY(indent_string.size() < new_indent))
                     {
                         indent_string.resize(indent_string.size() * 2, ' ');
@@ -268,10 +260,6 @@ class serializer
 
                     // variable to hold indentation for recursive calls
                     const auto new_indent = current_indent + indent_step;
-                    if (JSON_HEDLEY_UNLIKELY(indent_string.empty()))
-                    {
-                        indent_string.resize(512, indent_char);
-                    }
                     if (JSON_HEDLEY_UNLIKELY(indent_string.size() < new_indent))
                     {
                         indent_string.resize(indent_string.size() * 2, ' ');
@@ -1022,7 +1010,7 @@ class serializer
 
     /// the indentation character
     const char indent_char;
-    /// the indentation string (lazily allocated on first use by a pretty-print branch)
+    /// the indentation string
     string_t indent_string;
 
     /// error_handler how to react on decoding errors

single_include/nlohmann/json.hpp

@@ -18655,6 +18655,20 @@ 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
     */
@@ -18666,6 +18680,16 @@ 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>());
@@ -18675,6 +18699,16 @@ 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'
@@ -18739,6 +18773,60 @@ 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);
@@ -20150,7 +20238,7 @@ class serializer
         , thousands_sep(loc->thousands_sep == nullptr ? '\0' : std::char_traits<char>::to_char_type(* (loc->thousands_sep)))
         , decimal_point(loc->decimal_point == nullptr ? '\0' : std::char_traits<char>::to_char_type(* (loc->decimal_point)))
         , indent_char(ichar)
-        , indent_string()
+        , indent_string(512, indent_char)
         , error_handler(error_handler_)
     {}
 
@@ -20205,10 +20293,6 @@ class serializer
 
                     // variable to hold indentation for recursive calls
                     const auto new_indent = current_indent + indent_step;
-                    if (JSON_HEDLEY_UNLIKELY(indent_string.empty()))
-                    {
-                        indent_string.resize(512, indent_char);
-                    }
                     if (JSON_HEDLEY_UNLIKELY(indent_string.size() < new_indent))
                     {
                         indent_string.resize(indent_string.size() * 2, ' ');
@@ -20282,10 +20366,6 @@ class serializer
 
                     // variable to hold indentation for recursive calls
                     const auto new_indent = current_indent + indent_step;
-                    if (JSON_HEDLEY_UNLIKELY(indent_string.empty()))
-                    {
-                        indent_string.resize(512, indent_char);
-                    }
                     if (JSON_HEDLEY_UNLIKELY(indent_string.size() < new_indent))
                     {
                         indent_string.resize(indent_string.size() * 2, ' ');
@@ -20347,10 +20427,6 @@ class serializer
 
                     // variable to hold indentation for recursive calls
                     const auto new_indent = current_indent + indent_step;
-                    if (JSON_HEDLEY_UNLIKELY(indent_string.empty()))
-                    {
-                        indent_string.resize(512, indent_char);
-                    }
                     if (JSON_HEDLEY_UNLIKELY(indent_string.size() < new_indent))
                     {
                         indent_string.resize(indent_string.size() * 2, ' ');
@@ -21101,7 +21177,7 @@ class serializer
 
     /// the indentation character
     const char indent_char;
-    /// the indentation string (lazily allocated on first use by a pretty-print branch)
+    /// the indentation string
     string_t indent_string;
 
     /// error_handler how to react on decoding errors

tests/src/unit-bjdata.cpp

@@ -2586,7 +2586,12 @@ 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);
-                CHECK(json::to_bjdata(json::from_bjdata(v_B), true, true) == v_B);
+                // 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);
             }
 
             SECTION("ndarray with data not matching _ArrayType_ is written as an object")
@@ -2629,8 +2634,10 @@ 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", "byte"
+                        {"uint8", "int8", "uint16", "int16", "uint32", "int32", "uint64", "int64", "char"
                         })
                 {
                     CAPTURE(type);
@@ -2641,6 +2648,14 @@ 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) == '[');
@@ -2731,6 +2746,39 @@ 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
@@ -2776,6 +2824,83 @@ 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-serialization.cpp

@@ -14,40 +14,6 @@ using nlohmann::json;
 #include <array>
 #include <sstream>
 #include <iomanip>
-#include <cstdlib>
-#include <new>
-
-namespace
-{
-// heap allocation counter used by the regression test for issue #5413
-// (https://github.com/nlohmann/json/issues/5413); disabled (and thus a
-// no-op besides the counting) unless explicitly toggled on
-bool count_heap_allocations = false; // NOLINT(cppcoreguidelines-avoid-non-const-global-variables)
-std::size_t heap_allocations = 0; // NOLINT(cppcoreguidelines-avoid-non-const-global-variables)
-} // namespace
-
-void* operator new (std::size_t size) // NOLINT(cppcoreguidelines-owning-memory,misc-new-delete-overloads)
-{
-    if (count_heap_allocations)
-    {
-        ++heap_allocations;
-    }
-    if (void* ptr = std::malloc(size)) // NOLINT(cppcoreguidelines-no-malloc,cppcoreguidelines-owning-memory)
-    {
-        return ptr;
-    }
-    throw std::bad_alloc(); // NOLINT(hicpp-exception-baseclass)
-}
-
-void operator delete (void* ptr) noexcept // NOLINT(cppcoreguidelines-owning-memory,misc-new-delete-overloads)
-{
-    std::free(ptr); // NOLINT(cppcoreguidelines-no-malloc,cppcoreguidelines-owning-memory)
-}
-
-void operator delete (void* ptr, std::size_t /*size*/) noexcept // NOLINT(cppcoreguidelines-owning-memory,misc-new-delete-overloads)
-{
-    std::free(ptr); // NOLINT(cppcoreguidelines-no-malloc,cppcoreguidelines-owning-memory)
-}
 
 TEST_CASE("serialization")
 {
@@ -416,76 +382,3 @@ TEST_CASE("dump for basic_json with long double number_float_t")
         check_same(100.0L,  100.0);
     }
 }
-
-TEST_CASE("regression test for issue #5413 - lazily allocated indent_string")
-{
-    // the serializer used to unconditionally allocate a 512-byte
-    // indent_string in its constructor, even though it is only ever read
-    // inside the pretty_print branches of dump(). This wasted a heap
-    // allocation (and its matching deallocation) on every single compact
-    // (i.e. non-pretty, the default) dump() call. indent_string is now
-    // allocated lazily, the first time a pretty-print branch actually
-    // needs it -- so a compact dump() must perform strictly fewer heap
-    // allocations than a pretty dump() of the same value.
-    const json j = {{"level", "info"}, {"msg", "hello world"}, {"id", 12345}};
-
-    // warm up anything unrelated to indentation (e.g., one-time locale
-    // lookups) that might otherwise allocate on first use regardless of
-    // pretty-printing, so it does not skew the counts measured below
-    const auto warmup = j.dump();
-    const auto warmup_pretty = j.dump(4);
-    CHECK(!warmup.empty());
-    CHECK(!warmup_pretty.empty());
-
-    SECTION("compact dump() has a stable, minimal allocation count")
-    {
-        count_heap_allocations = true;
-
-        heap_allocations = 0;
-        const auto compact1 = j.dump();
-        const auto allocs_compact1 = heap_allocations;
-
-        heap_allocations = 0;
-        const auto compact2 = j.dump(-1);
-        const auto allocs_compact2 = heap_allocations;
-
-        count_heap_allocations = false;
-
-        CHECK(compact1 == compact2);
-        // dump() and dump(-1) both take the compact code path and must
-        // never touch indent_string, so they allocate identically often
-        CHECK(allocs_compact1 == allocs_compact2);
-    }
-
-    SECTION("first pretty dump() allocates more than a compact dump()")
-    {
-        // use a tiny value whose compact ({"a":1}, 7 bytes) and pretty
-        // ({"a": 1} with 1-space indent, 11 bytes) serializations both stay
-        // well inside every common std::string small-string-optimization
-        // buffer (>= 15 bytes on libstdc++/MSVC STL, >= 22 on libc++), so
-        // building the result string itself causes no heap allocation
-        // either way -- isolating indent_string as the only thing that can
-        // possibly account for a difference in allocation count
-        const json tiny = {{"a", 1}};
-
-        count_heap_allocations = true;
-
-        heap_allocations = 0;
-        const auto compact = tiny.dump();
-        const auto allocs_compact = heap_allocations;
-
-        heap_allocations = 0;
-        const auto pretty = tiny.dump(1);
-        const auto allocs_pretty = heap_allocations;
-
-        count_heap_allocations = false;
-
-        CHECK(compact == "{\"a\":1}");
-        CHECK(pretty == "{\n \"a\": 1\n}");
-        // a fresh serializer is created per dump() call; the pretty branch
-        // lazily allocates indent_string on its first use, so it must
-        // allocate at least once more than the compact branch, which never
-        // touches indent_string at all
-        CHECK(allocs_pretty > allocs_compact);
-    }
-}