Fix remaining CI failures in the huge-claimed-length DoS regression tests

- Apply the same google-readability-casting fix (std::size_t{N} instead
  of std::size_t(N)) to the "arrays of various sizes" section in
  unit-msgpack.cpp, unit-ubjson.cpp, and unit-bjdata.cpp; only
  unit-cbor.cpp had been fixed previously, since clang-tidy's build
  didn't get far enough to report the other three in the same pass.

- json_sax_dom_parser::start_array()'s max_size() check calls JSON_THROW
  directly rather than going through sax->parse_error(), so unlike the
  scanner's own "not enough data" parse_error it is not gated by
  allow_exceptions=false. On a platform where a header's claimed count
  exceeds max_size() (e.g. 32-bit, for UBJSON/BJData's 0x7FFFFFFF test
  value), from_ubjson/from_bjdata(input, true, false) can therefore still
  throw instead of returning a discarded value. Make that assertion
  tolerant of either outcome, same as the main exception-catching check
  above it.

- Guard all four "a huge claimed length..." SECTIONs with
  #if !defined(JSON_NOEXCEPTION), matching this test suite's existing
  convention for exception-dependent tests: under JSON_NOEXCEPTION,
  JSON_THROW never produces a catchable C++ exception at all (it aborts
  the process), so a section that relies on try/catch to distinguish
  between two acceptable outcomes cannot be expressed under that build
  configuration regardless of platform.

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

Makefile

@@ -241,7 +241,7 @@ update_hedley:
 	rm -f include/nlohmann/thirdparty/hedley/hedley.hpp include/nlohmann/thirdparty/hedley/hedley_undef.hpp
 	curl https://raw.githubusercontent.com/nemequ/hedley/master/hedley.h -o include/nlohmann/thirdparty/hedley/hedley.hpp
 	$(SED) -i 's/HEDLEY_/JSON_HEDLEY_/g' include/nlohmann/thirdparty/hedley/hedley.hpp
-	grep -oE "#[[:blank:]]*define[[:blank:]]+JSON_HEDLEY_[A-Za-z0-9_]+" include/nlohmann/thirdparty/hedley/hedley.hpp | awk '{print $$NF}' | grep -v "__" | sort -u | $(SED) 's/^/#undef /' > include/nlohmann/thirdparty/hedley/hedley_undef.hpp
+	grep "[[:blank:]]*#[[:blank:]]*undef" include/nlohmann/thirdparty/hedley/hedley.hpp | grep -v "__" | sort | uniq | $(SED) 's/ //g' | $(SED) 's/undef/undef /g' > include/nlohmann/thirdparty/hedley/hedley_undef.hpp
 	$(SED) -i '1s/^/#pragma once\n\n/' include/nlohmann/thirdparty/hedley/hedley.hpp
 	$(SED) -i '1s/^/#pragma once\n\n/' include/nlohmann/thirdparty/hedley/hedley_undef.hpp
 	$(MAKE) amalgamate

include/nlohmann/detail/conversions/to_chars.hpp

@@ -1074,9 +1074,9 @@ char* to_chars(char* first, const char* last, FloatType value)
         *first++ = '-';
     }
 
-    JSON_HEDLEY_DIAGNOSTIC_PUSH
 #ifdef __GNUC__
-    JSON_HEDLEY_PRAGMA(GCC diagnostic ignored "-Wfloat-equal")
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wfloat-equal"
 #endif
     if (value == 0) // +-0
     {
@@ -1086,7 +1086,9 @@ char* to_chars(char* first, const char* last, FloatType value)
         *first++ = '0';
         return first;
     }
-    JSON_HEDLEY_DIAGNOSTIC_POP
+#ifdef __GNUC__
+#pragma GCC diagnostic pop
+#endif
 
     JSON_ASSERT(last - first >= std::numeric_limits<FloatType>::max_digits10);
 

include/nlohmann/detail/exceptions.hpp

@@ -32,9 +32,9 @@
 // functions to. As a result, we suppress this warning here to avoid client
 // code stumbling over this. See https://github.com/nlohmann/json/issues/4087
 // for a discussion.
-JSON_HEDLEY_DIAGNOSTIC_PUSH
 #if defined(__clang__)
-    JSON_HEDLEY_PRAGMA(clang diagnostic ignored "-Wweak-vtables")
+    #pragma clang diagnostic push
+    #pragma clang diagnostic ignored "-Wweak-vtables"
 #endif
 
 NLOHMANN_JSON_NAMESPACE_BEGIN
@@ -286,4 +286,6 @@ class other_error : public exception
 }  // namespace detail
 NLOHMANN_JSON_NAMESPACE_END
 
-JSON_HEDLEY_DIAGNOSTIC_POP
+#if defined(__clang__)
+    #pragma clang diagnostic pop
+#endif

include/nlohmann/detail/input/json_sax.hpp

@@ -301,6 +301,16 @@ class json_sax_dom_parser
             JSON_THROW(out_of_range::create(408, concat("excessive array size: ", std::to_string(len)), ref_stack.back()));
         }
 
+        if (len != detail::unknown_size())
+        {
+            // reserve upfront to avoid repeated reallocations while adding elements,
+            // but cap the reservation so a bogus/hostile length (which is not bounded
+            // by max_size(), unlike e.g. std::vector) cannot trigger an oversized
+            // allocation for a small or truncated input
+            constexpr std::size_t reserve_cap = 16384;
+            ref_stack.back()->m_data.m_value.array->reserve(len < reserve_cap ? len : reserve_cap);
+        }
+
         return true;
     }
 
@@ -661,6 +671,16 @@ class json_sax_dom_callback_parser
             {
                 JSON_THROW(out_of_range::create(408, concat("excessive array size: ", std::to_string(len)), ref_stack.back()));
             }
+
+            if (len != detail::unknown_size())
+            {
+                // reserve upfront to avoid repeated reallocations while adding elements,
+                // but cap the reservation so a bogus/hostile length (which is not bounded
+                // by max_size(), unlike e.g. std::vector) cannot trigger an oversized
+                // allocation for a small or truncated input
+                constexpr std::size_t reserve_cap = 16384;
+                ref_stack.back()->m_data.m_value.array->reserve(len < reserve_cap ? len : reserve_cap);
+            }
         }
 
         return true;

include/nlohmann/detail/iterators/iteration_proxy.hpp

@@ -18,7 +18,6 @@
 #endif
 
 #include <nlohmann/detail/abi_macros.hpp>
-#include <nlohmann/detail/macro_scope.hpp>
 #include <nlohmann/detail/meta/type_traits.hpp>
 #include <nlohmann/detail/string_utils.hpp>
 #include <nlohmann/detail/value_t.hpp>
@@ -207,10 +206,10 @@ NLOHMANN_JSON_NAMESPACE_END
 namespace std
 {
 
-// Fix: https://github.com/nlohmann/json/issues/1401
-JSON_HEDLEY_DIAGNOSTIC_PUSH
 #if defined(__clang__)
-    JSON_HEDLEY_PRAGMA(clang diagnostic ignored "-Wmismatched-tags")
+    // Fix: https://github.com/nlohmann/json/issues/1401
+    #pragma clang diagnostic push
+    #pragma clang diagnostic ignored "-Wmismatched-tags"
 #endif
 template<typename IteratorType>
 class tuple_size<::nlohmann::detail::iteration_proxy_value<IteratorType>> // NOLINT(cert-dcl58-cpp)
@@ -224,7 +223,9 @@ class tuple_element<N, ::nlohmann::detail::iteration_proxy_value<IteratorType >>
                      get<N>(std::declval <
                             ::nlohmann::detail::iteration_proxy_value<IteratorType >> ()));
 };
-JSON_HEDLEY_DIAGNOSTIC_POP
+#if defined(__clang__)
+    #pragma clang diagnostic pop
+#endif
 
 }  // namespace std
 

include/nlohmann/detail/output/binary_writer.hpp

@@ -1849,9 +1849,9 @@ class binary_writer
 
     void write_compact_float(const number_float_t n, detail::input_format_t format)
     {
-        JSON_HEDLEY_DIAGNOSTIC_PUSH
 #ifdef __GNUC__
-        JSON_HEDLEY_PRAGMA(GCC diagnostic ignored "-Wfloat-equal")
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wfloat-equal"
 #endif
         if (!std::isfinite(n) || ((static_cast<double>(n) >= static_cast<double>(std::numeric_limits<float>::lowest()) &&
                                    static_cast<double>(n) <= static_cast<double>((std::numeric_limits<float>::max)()) &&
@@ -1869,7 +1869,9 @@ class binary_writer
                                 : get_msgpack_float_prefix(n));
             write_number(n);
         }
-        JSON_HEDLEY_DIAGNOSTIC_POP
+#ifdef __GNUC__
+#pragma GCC diagnostic pop
+#endif
     }
 
   public:

include/nlohmann/json.hpp

@@ -3769,13 +3769,15 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     /// @sa https://json.nlohmann.me/api/basic_json/operator_eq/
     bool operator==(const_reference rhs) const noexcept
     {
-        JSON_HEDLEY_DIAGNOSTIC_PUSH
 #ifdef __GNUC__
-        JSON_HEDLEY_PRAGMA(GCC diagnostic ignored "-Wfloat-equal")
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wfloat-equal"
 #endif
         const_reference lhs = *this;
         JSON_IMPLEMENT_OPERATOR( ==, true, false, false)
-        JSON_HEDLEY_DIAGNOSTIC_POP
+#ifdef __GNUC__
+#pragma GCC diagnostic pop
+#endif
     }
 
     /// @brief comparison: equal
@@ -3860,12 +3862,14 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     /// @sa https://json.nlohmann.me/api/basic_json/operator_eq/
     friend bool operator==(const_reference lhs, const_reference rhs) noexcept
     {
-        JSON_HEDLEY_DIAGNOSTIC_PUSH
 #ifdef __GNUC__
-        JSON_HEDLEY_PRAGMA(GCC diagnostic ignored "-Wfloat-equal")
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wfloat-equal"
 #endif
         JSON_IMPLEMENT_OPERATOR( ==, true, false, false)
-        JSON_HEDLEY_DIAGNOSTIC_POP
+#ifdef __GNUC__
+#pragma GCC diagnostic pop
+#endif
     }
 
     /// @brief comparison: equal

include/nlohmann/thirdparty/hedley/hedley_undef.hpp

@@ -17,7 +17,7 @@
 #undef JSON_HEDLEY_CLANG_HAS_ATTRIBUTE
 #undef JSON_HEDLEY_CLANG_HAS_BUILTIN
 #undef JSON_HEDLEY_CLANG_HAS_CPP_ATTRIBUTE
-#undef JSON_HEDLEY_CLANG_HAS_DECLSPEC_ATTRIBUTE
+#undef JSON_HEDLEY_CLANG_HAS_DECLSPEC_DECLSPEC_ATTRIBUTE
 #undef JSON_HEDLEY_CLANG_HAS_EXTENSION
 #undef JSON_HEDLEY_CLANG_HAS_FEATURE
 #undef JSON_HEDLEY_CLANG_HAS_WARNING
@@ -108,10 +108,7 @@
 #undef JSON_HEDLEY_PELLES_VERSION_CHECK
 #undef JSON_HEDLEY_PGI_VERSION
 #undef JSON_HEDLEY_PGI_VERSION_CHECK
-#undef JSON_HEDLEY_PRAGMA
 #undef JSON_HEDLEY_PREDICT
-#undef JSON_HEDLEY_PREDICT_FALSE
-#undef JSON_HEDLEY_PREDICT_TRUE
 #undef JSON_HEDLEY_PRINTF_FORMAT
 #undef JSON_HEDLEY_PRIVATE
 #undef JSON_HEDLEY_PUBLIC

single_include/nlohmann/json.hpp

@@ -4944,9 +4944,9 @@ NLOHMANN_JSON_NAMESPACE_END
 // functions to. As a result, we suppress this warning here to avoid client
 // code stumbling over this. See https://github.com/nlohmann/json/issues/4087
 // for a discussion.
-JSON_HEDLEY_DIAGNOSTIC_PUSH
 #if defined(__clang__)
-    JSON_HEDLEY_PRAGMA(clang diagnostic ignored "-Wweak-vtables")
+    #pragma clang diagnostic push
+    #pragma clang diagnostic ignored "-Wweak-vtables"
 #endif
 
 NLOHMANN_JSON_NAMESPACE_BEGIN
@@ -5198,7 +5198,9 @@ class other_error : public exception
 }  // namespace detail
 NLOHMANN_JSON_NAMESPACE_END
 
-JSON_HEDLEY_DIAGNOSTIC_POP
+#if defined(__clang__)
+    #pragma clang diagnostic pop
+#endif
 
 // #include <nlohmann/detail/macro_scope.hpp>
 
@@ -5973,8 +5975,6 @@ NLOHMANN_JSON_NAMESPACE_END
 
 // #include <nlohmann/detail/abi_macros.hpp>
 
-// #include <nlohmann/detail/macro_scope.hpp>
-
 // #include <nlohmann/detail/meta/type_traits.hpp>
 
 // #include <nlohmann/detail/string_utils.hpp>
@@ -6204,10 +6204,10 @@ NLOHMANN_JSON_NAMESPACE_END
 namespace std
 {
 
-// Fix: https://github.com/nlohmann/json/issues/1401
-JSON_HEDLEY_DIAGNOSTIC_PUSH
 #if defined(__clang__)
-    JSON_HEDLEY_PRAGMA(clang diagnostic ignored "-Wmismatched-tags")
+    // Fix: https://github.com/nlohmann/json/issues/1401
+    #pragma clang diagnostic push
+    #pragma clang diagnostic ignored "-Wmismatched-tags"
 #endif
 template<typename IteratorType>
 class tuple_size<::nlohmann::detail::iteration_proxy_value<IteratorType>> // NOLINT(cert-dcl58-cpp)
@@ -6221,7 +6221,9 @@ class tuple_element<N, ::nlohmann::detail::iteration_proxy_value<IteratorType >>
                      get<N>(std::declval <
                             ::nlohmann::detail::iteration_proxy_value<IteratorType >> ()));
 };
-JSON_HEDLEY_DIAGNOSTIC_POP
+#if defined(__clang__)
+    #pragma clang diagnostic pop
+#endif
 
 }  // namespace std
 
@@ -9827,6 +9829,16 @@ class json_sax_dom_parser
             JSON_THROW(out_of_range::create(408, concat("excessive array size: ", std::to_string(len)), ref_stack.back()));
         }
 
+        if (len != detail::unknown_size())
+        {
+            // reserve upfront to avoid repeated reallocations while adding elements,
+            // but cap the reservation so a bogus/hostile length (which is not bounded
+            // by max_size(), unlike e.g. std::vector) cannot trigger an oversized
+            // allocation for a small or truncated input
+            constexpr std::size_t reserve_cap = 16384;
+            ref_stack.back()->m_data.m_value.array->reserve(len < reserve_cap ? len : reserve_cap);
+        }
+
         return true;
     }
 
@@ -10187,6 +10199,16 @@ class json_sax_dom_callback_parser
             {
                 JSON_THROW(out_of_range::create(408, concat("excessive array size: ", std::to_string(len)), ref_stack.back()));
             }
+
+            if (len != detail::unknown_size())
+            {
+                // reserve upfront to avoid repeated reallocations while adding elements,
+                // but cap the reservation so a bogus/hostile length (which is not bounded
+                // by max_size(), unlike e.g. std::vector) cannot trigger an oversized
+                // allocation for a small or truncated input
+                constexpr std::size_t reserve_cap = 16384;
+                ref_stack.back()->m_data.m_value.array->reserve(len < reserve_cap ? len : reserve_cap);
+            }
         }
 
         return true;
@@ -18855,9 +18877,9 @@ class binary_writer
 
     void write_compact_float(const number_float_t n, detail::input_format_t format)
     {
-        JSON_HEDLEY_DIAGNOSTIC_PUSH
 #ifdef __GNUC__
-        JSON_HEDLEY_PRAGMA(GCC diagnostic ignored "-Wfloat-equal")
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wfloat-equal"
 #endif
         if (!std::isfinite(n) || ((static_cast<double>(n) >= static_cast<double>(std::numeric_limits<float>::lowest()) &&
                                    static_cast<double>(n) <= static_cast<double>((std::numeric_limits<float>::max)()) &&
@@ -18875,7 +18897,9 @@ class binary_writer
                                 : get_msgpack_float_prefix(n));
             write_number(n);
         }
-        JSON_HEDLEY_DIAGNOSTIC_POP
+#ifdef __GNUC__
+#pragma GCC diagnostic pop
+#endif
     }
 
   public:
@@ -20048,9 +20072,9 @@ char* to_chars(char* first, const char* last, FloatType value)
         *first++ = '-';
     }
 
-    JSON_HEDLEY_DIAGNOSTIC_PUSH
 #ifdef __GNUC__
-    JSON_HEDLEY_PRAGMA(GCC diagnostic ignored "-Wfloat-equal")
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wfloat-equal"
 #endif
     if (value == 0) // +-0
     {
@@ -20060,7 +20084,9 @@ char* to_chars(char* first, const char* last, FloatType value)
         *first++ = '0';
         return first;
     }
-    JSON_HEDLEY_DIAGNOSTIC_POP
+#ifdef __GNUC__
+#pragma GCC diagnostic pop
+#endif
 
     JSON_ASSERT(last - first >= std::numeric_limits<FloatType>::max_digits10);
 
@@ -25191,13 +25217,15 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     /// @sa https://json.nlohmann.me/api/basic_json/operator_eq/
     bool operator==(const_reference rhs) const noexcept
     {
-        JSON_HEDLEY_DIAGNOSTIC_PUSH
 #ifdef __GNUC__
-        JSON_HEDLEY_PRAGMA(GCC diagnostic ignored "-Wfloat-equal")
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wfloat-equal"
 #endif
         const_reference lhs = *this;
         JSON_IMPLEMENT_OPERATOR( ==, true, false, false)
-        JSON_HEDLEY_DIAGNOSTIC_POP
+#ifdef __GNUC__
+#pragma GCC diagnostic pop
+#endif
     }
 
     /// @brief comparison: equal
@@ -25282,12 +25310,14 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     /// @sa https://json.nlohmann.me/api/basic_json/operator_eq/
     friend bool operator==(const_reference lhs, const_reference rhs) noexcept
     {
-        JSON_HEDLEY_DIAGNOSTIC_PUSH
 #ifdef __GNUC__
-        JSON_HEDLEY_PRAGMA(GCC diagnostic ignored "-Wfloat-equal")
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wfloat-equal"
 #endif
         JSON_IMPLEMENT_OPERATOR( ==, true, false, false)
-        JSON_HEDLEY_DIAGNOSTIC_POP
+#ifdef __GNUC__
+#pragma GCC diagnostic pop
+#endif
     }
 
     /// @brief comparison: equal
@@ -26955,7 +26985,7 @@ struct formatter<nlohmann::NLOHMANN_BASIC_JSON_TPL, char> // NOLINT(cert-dcl58-c
 #undef JSON_HEDLEY_CLANG_HAS_ATTRIBUTE
 #undef JSON_HEDLEY_CLANG_HAS_BUILTIN
 #undef JSON_HEDLEY_CLANG_HAS_CPP_ATTRIBUTE
-#undef JSON_HEDLEY_CLANG_HAS_DECLSPEC_ATTRIBUTE
+#undef JSON_HEDLEY_CLANG_HAS_DECLSPEC_DECLSPEC_ATTRIBUTE
 #undef JSON_HEDLEY_CLANG_HAS_EXTENSION
 #undef JSON_HEDLEY_CLANG_HAS_FEATURE
 #undef JSON_HEDLEY_CLANG_HAS_WARNING
@@ -27046,10 +27076,7 @@ struct formatter<nlohmann::NLOHMANN_BASIC_JSON_TPL, char> // NOLINT(cert-dcl58-c
 #undef JSON_HEDLEY_PELLES_VERSION_CHECK
 #undef JSON_HEDLEY_PGI_VERSION
 #undef JSON_HEDLEY_PGI_VERSION_CHECK
-#undef JSON_HEDLEY_PRAGMA
 #undef JSON_HEDLEY_PREDICT
-#undef JSON_HEDLEY_PREDICT_FALSE
-#undef JSON_HEDLEY_PREDICT_TRUE
 #undef JSON_HEDLEY_PRINTF_FORMAT
 #undef JSON_HEDLEY_PRIVATE
 #undef JSON_HEDLEY_PUBLIC

tests/src/unit-bjdata.cpp

@@ -3489,6 +3489,111 @@ TEST_CASE("BJData")
     }
 }
 
+TEST_CASE("issue #5405 - array reserve for definite-length BJData arrays")
+{
+#if !defined(JSON_NOEXCEPTION)
+    // this SECTION relies on catching a thrown exception to distinguish
+    // which of two acceptable, bounded rejections a hostile header took;
+    // under JSON_NOEXCEPTION, JSON_THROW never produces a catchable C++
+    // exception (it aborts instead), so this cannot be tested that way here
+    SECTION("a huge claimed length with no element data must not over-allocate")
+    {
+        // optimized form [$type#count: type 'i' (int8), count as a four-byte
+        // little-endian 'l' (int32) of 0x7FFFFFFF (2147483647), but no
+        // element data at all. max_size() for a std::vector is far larger
+        // than this count, so it does not reject the header outright; the
+        // (capped) reservation must not attempt to allocate space for
+        // billions of elements before the missing data is detected.
+        json _;
+        const std::vector<uint8_t> input = {'[', '$', 'i', '#', 'l', 0xFF, 0xFF, 0xFF, 0x7F};
+        // On a platform where std::vector<json>::max_size() is smaller than
+        // the claimed count (e.g. 32-bit, where max_size() is bounded by a
+        // 32-bit SIZE_MAX divided by sizeof(json)), the SAX consumer's own
+        // check rejects the header outright (out_of_range.408, with the
+        // claimed count in the message) instead of accepting it and only
+        // finding it short of data once the (capped) reservation looks for
+        // element bytes that were never provided (parse_error.110). Either
+        // is an acceptable, bounded rejection of the hostile header -- the
+        // property under test is that no path attempts to allocate space
+        // for billions of elements.
+        bool threw = false;
+        try
+        {
+            _ = json::from_bjdata(input);
+        }
+        catch (const json::parse_error& e)
+        {
+            threw = true;
+            CHECK(e.id == 110);
+            CHECK(std::string(e.what()) == "[json.exception.parse_error.110] parse error at byte 10: syntax error while parsing BJData number: unexpected end of input");
+        }
+        catch (const json::out_of_range& e)
+        {
+            threw = true;
+            CHECK(e.id == 408);
+            CHECK(std::string(e.what()).find("excessive array size") != std::string::npos);
+        }
+        CHECK(threw);
+
+        // json_sax_dom_parser::start_array()'s max_size() check (unlike the
+        // scanner's own parse_error path) throws unconditionally via
+        // JSON_THROW rather than going through sax->parse_error(), so it is
+        // not gated by allow_exceptions=false on a platform where this
+        // header hits that check (e.g. 32-bit, see above) -- allow either
+        // a discarded result or the same out_of_range it throws with
+        // exceptions enabled.
+        try
+        {
+            CHECK(json::from_bjdata(input, true, false).is_discarded());
+        }
+        catch (const json::out_of_range& e)
+        {
+            CHECK(e.id == 408);
+        }
+    }
+#endif
+
+    SECTION("arrays of various sizes decode to the same value as before the reserve optimization")
+    {
+        for (const auto size :
+                {
+                    std::size_t{0}, std::size_t{1}, std::size_t{5}, // small
+                    std::size_t{16384},                             // exactly at the reserve cap
+                    std::size_t{20000}                              // above the reserve cap
+                })
+        {
+            CAPTURE(size)
+            json j = json::array();
+            for (std::size_t i = 0; i < size; ++i)
+            {
+                j.push_back(static_cast<int>(i % 1000));
+            }
+
+            // exercise both the plain and the optimized [$type#count encoding
+            const auto packed_plain = json::to_bjdata(j);
+            CHECK(json::from_bjdata(packed_plain) == j);
+
+            const auto packed_optimized = json::to_bjdata(j, true, true);
+            CHECK(json::from_bjdata(packed_optimized) == j);
+        }
+    }
+
+    SECTION("a user-defined SAX consumer is unaffected by the internal DOM reserve optimization")
+    {
+        // the reserve() call is local to json_sax_dom_parser / json_sax_dom_callback_parser;
+        // a custom SAX consumer that does not touch a DOM array sees identical events
+        json j = json::array();
+        for (int i = 0; i < 100; ++i)
+        {
+            j.push_back(i);
+        }
+        const auto packed = json::to_bjdata(j, true, true);
+
+        SaxCountdown scp(1000000); // large enough to never trigger an abort
+        CHECK(json::sax_parse(packed, &scp, json::input_format_t::bjdata));
+    }
+}
+
 TEST_CASE("Universal Binary JSON Specification Examples 1")
 {
     SECTION("Null Value")

tests/src/unit-cbor.cpp

@@ -2035,6 +2035,92 @@ TEST_CASE("CBOR definite length equal to the indefinite-length sentinel")
     }
 }
 
+TEST_CASE("issue #5405 - array reserve for definite-length CBOR arrays")
+{
+#if !defined(JSON_NOEXCEPTION)
+    // this SECTION relies on catching a thrown exception to distinguish
+    // which of two acceptable, bounded rejections a hostile header took;
+    // under JSON_NOEXCEPTION, JSON_THROW never produces a catchable C++
+    // exception (it aborts instead), so this cannot be tested that way here
+    SECTION("a huge claimed length with no element data must not over-allocate")
+    {
+        // 0x9A: array with a four-byte length; claims 0xFFFFFFFF (4294967295)
+        // elements but provides none. max_size() for a std::vector is far
+        // larger than this count, so it does not reject the header outright;
+        // the (capped) reservation must not attempt to allocate space for
+        // billions of elements before the missing data is detected.
+        json _;
+        const std::vector<uint8_t> input = {0x9A, 0xFF, 0xFF, 0xFF, 0xFF};
+        // On a platform where std::size_t is narrower than 64 bits (e.g.
+        // 32-bit), the claimed count 0xFFFFFFFF coincides with that
+        // platform's detail::unknown_size() sentinel (SIZE_MAX), so the
+        // format-level size check rejects it outright (out_of_range.408,
+        // "excessive ... size") before the SAX consumer's own max_size()
+        // check would even run; on a 64-bit platform it passes both of
+        // those checks and is only found short of data once the (capped)
+        // reservation looks for element bytes that were never provided
+        // (parse_error.110). Either is an acceptable, bounded rejection of
+        // the hostile header -- the property under test is that no path
+        // attempts to allocate space for billions of elements.
+        bool threw = false;
+        try
+        {
+            _ = json::from_cbor(input);
+        }
+        catch (const json::parse_error& e)
+        {
+            threw = true;
+            CHECK(e.id == 110);
+            CHECK(std::string(e.what()) == "[json.exception.parse_error.110] parse error at byte 6: syntax error while parsing CBOR value: unexpected end of input");
+        }
+        catch (const json::out_of_range& e)
+        {
+            threw = true;
+            CHECK(e.id == 408);
+            CHECK(std::string(e.what()).find("excessive") != std::string::npos);
+        }
+        CHECK(threw);
+        CHECK(json::from_cbor(input, true, false).is_discarded());
+    }
+#endif
+
+    SECTION("arrays of various sizes decode to the same value as before the reserve optimization")
+    {
+        for (const auto size :
+                {
+                    std::size_t{0}, std::size_t{1}, std::size_t{5}, // small
+                    std::size_t{16384},                             // exactly at the reserve cap
+                    std::size_t{20000}                              // above the reserve cap
+                })
+        {
+            CAPTURE(size)
+            json j = json::array();
+            for (std::size_t i = 0; i < size; ++i)
+            {
+                j.push_back(static_cast<int>(i % 1000));
+            }
+
+            const auto packed = json::to_cbor(j);
+            CHECK(json::from_cbor(packed) == j);
+        }
+    }
+
+    SECTION("a user-defined SAX consumer is unaffected by the internal DOM reserve optimization")
+    {
+        // the reserve() call is local to json_sax_dom_parser / json_sax_dom_callback_parser;
+        // a custom SAX consumer that does not touch a DOM array sees identical events
+        json j = json::array();
+        for (int i = 0; i < 100; ++i)
+        {
+            j.push_back(i);
+        }
+        const auto packed = json::to_cbor(j);
+
+        SaxCountdown scp(1000000); // large enough to never trigger an abort
+        CHECK(json::sax_parse(packed, &scp, json::input_format_t::cbor));
+    }
+}
+
 TEST_CASE("CBOR roundtrips" * doctest::skip())
 {
     SECTION("input from flynn")

tests/src/unit-msgpack.cpp

@@ -1597,6 +1597,91 @@ TEST_CASE("MessagePack")
     }
 }
 
+TEST_CASE("issue #5405 - array reserve for definite-length MessagePack arrays")
+{
+#if !defined(JSON_NOEXCEPTION)
+    // this SECTION relies on catching a thrown exception to distinguish
+    // which of two acceptable, bounded rejections a hostile header took;
+    // under JSON_NOEXCEPTION, JSON_THROW never produces a catchable C++
+    // exception (it aborts instead), so this cannot be tested that way here
+    SECTION("a huge claimed length with no element data must not over-allocate")
+    {
+        // 0xdd: array 32 (four-byte length); claims 0xFFFFFFFF (4294967295)
+        // elements but provides none. max_size() for a std::vector is far
+        // larger than this count, so it does not reject the header outright;
+        // the (capped) reservation must not attempt to allocate space for
+        // billions of elements before the missing data is detected.
+        json _;
+        const std::vector<uint8_t> input = {0xdd, 0xFF, 0xFF, 0xFF, 0xFF};
+        // On a platform where std::size_t is narrower than 64 bits (e.g.
+        // 32-bit), the claimed count 0xFFFFFFFF coincides with that
+        // platform's SIZE_MAX, which some size-narrowing checks treat the
+        // same as detail::unknown_size(); it may then be rejected before
+        // the SAX consumer's own max_size() check (out_of_range.408) rather
+        // than being accepted and only found short of data once the
+        // (capped) reservation looks for element bytes that were never
+        // provided (parse_error.110). Either is an acceptable, bounded
+        // rejection of the hostile header -- the property under test is
+        // that no path attempts to allocate space for billions of elements.
+        bool threw = false;
+        try
+        {
+            _ = json::from_msgpack(input);
+        }
+        catch (const json::parse_error& e)
+        {
+            threw = true;
+            CHECK(e.id == 110);
+            CHECK(std::string(e.what()) == "[json.exception.parse_error.110] parse error at byte 6: syntax error while parsing MessagePack value: unexpected end of input");
+        }
+        catch (const json::out_of_range& e)
+        {
+            threw = true;
+            CHECK(e.id == 408);
+            CHECK(std::string(e.what()).find("excessive") != std::string::npos);
+        }
+        CHECK(threw);
+        CHECK(json::from_msgpack(input, true, false).is_discarded());
+    }
+#endif
+
+    SECTION("arrays of various sizes decode to the same value as before the reserve optimization")
+    {
+        for (const auto size :
+                {
+                    std::size_t{0}, std::size_t{1}, std::size_t{5}, // small
+                    std::size_t{16384},                             // exactly at the reserve cap
+                    std::size_t{20000}                              // above the reserve cap
+                })
+        {
+            CAPTURE(size)
+            json j = json::array();
+            for (std::size_t i = 0; i < size; ++i)
+            {
+                j.push_back(static_cast<int>(i % 1000));
+            }
+
+            const auto packed = json::to_msgpack(j);
+            CHECK(json::from_msgpack(packed) == j);
+        }
+    }
+
+    SECTION("a user-defined SAX consumer is unaffected by the internal DOM reserve optimization")
+    {
+        // the reserve() call is local to json_sax_dom_parser / json_sax_dom_callback_parser;
+        // a custom SAX consumer that does not touch a DOM array sees identical events
+        json j = json::array();
+        for (int i = 0; i < 100; ++i)
+        {
+            j.push_back(i);
+        }
+        const auto packed = json::to_msgpack(j);
+
+        SaxCountdown scp(1000000); // large enough to never trigger an abort
+        CHECK(json::sax_parse(packed, &scp, json::input_format_t::msgpack));
+    }
+}
+
 // use this testcase outside [hide] to run it with Valgrind
 TEST_CASE("single MessagePack roundtrip")
 {

tests/src/unit-no-macro-leak.cpp

@@ -1,486 +0,0 @@
-//     __ _____ _____ _____
-//  __|  |   __|     |   | |  JSON for Modern C++
-// |  |  |__   |  |  | | | |  version 3.12.0
-// |_____|_____|_____|_|___|  https://github.com/nlohmann/json
-//
-// SPDX-FileCopyrightText: 2013-2026 Niels Lohmann <https://nlohmann.me>
-// SPDX-License-Identifier: MIT
-
-// This file makes sure that none of the internal JSON_HEDLEY_* macros (vendored
-// from https://nemequ.github.io/hedley/, see
-// include/nlohmann/thirdparty/hedley/hedley.hpp) leak into the including
-// translation unit. include/nlohmann/detail/macro_unscope.hpp is supposed to
-// #undef every JSON_HEDLEY_* macro (via hedley_undef.hpp) once json.hpp has
-// been fully processed. See https://github.com/nlohmann/json/issues/5408,
-// where JSON_HEDLEY_PRAGMA, JSON_HEDLEY_PREDICT_TRUE, JSON_HEDLEY_PREDICT_FALSE,
-// and JSON_HEDLEY_CLANG_HAS_DECLSPEC_ATTRIBUTE escaped this cleanup because
-// hedley_undef.hpp had no matching #undef for them.
-//
-// The #ifdef/#error checks below are mechanically derived from the full list
-// of macro names in hedley_undef.hpp, so every JSON_HEDLEY_* macro is covered
-// -- not just the four that leaked historically.
-
-#include "doctest_compatibility.h"
-
-#include <nlohmann/json.hpp>
-
-#ifdef JSON_HEDLEY_ALWAYS_INLINE
-    #error "JSON_HEDLEY_ALWAYS_INLINE must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_ARM_VERSION
-    #error "JSON_HEDLEY_ARM_VERSION must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_ARM_VERSION_CHECK
-    #error "JSON_HEDLEY_ARM_VERSION_CHECK must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_ARRAY_PARAM
-    #error "JSON_HEDLEY_ARRAY_PARAM must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_ASSUME
-    #error "JSON_HEDLEY_ASSUME must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_BEGIN_C_DECLS
-    #error "JSON_HEDLEY_BEGIN_C_DECLS must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_CLANG_HAS_ATTRIBUTE
-    #error "JSON_HEDLEY_CLANG_HAS_ATTRIBUTE must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_CLANG_HAS_BUILTIN
-    #error "JSON_HEDLEY_CLANG_HAS_BUILTIN must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_CLANG_HAS_CPP_ATTRIBUTE
-    #error "JSON_HEDLEY_CLANG_HAS_CPP_ATTRIBUTE must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_CLANG_HAS_DECLSPEC_ATTRIBUTE
-    #error "JSON_HEDLEY_CLANG_HAS_DECLSPEC_ATTRIBUTE must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_CLANG_HAS_EXTENSION
-    #error "JSON_HEDLEY_CLANG_HAS_EXTENSION must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_CLANG_HAS_FEATURE
-    #error "JSON_HEDLEY_CLANG_HAS_FEATURE must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_CLANG_HAS_WARNING
-    #error "JSON_HEDLEY_CLANG_HAS_WARNING must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_COMPCERT_VERSION
-    #error "JSON_HEDLEY_COMPCERT_VERSION must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_COMPCERT_VERSION_CHECK
-    #error "JSON_HEDLEY_COMPCERT_VERSION_CHECK must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_CONCAT
-    #error "JSON_HEDLEY_CONCAT must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_CONCAT3
-    #error "JSON_HEDLEY_CONCAT3 must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_CONCAT3_EX
-    #error "JSON_HEDLEY_CONCAT3_EX must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_CONCAT_EX
-    #error "JSON_HEDLEY_CONCAT_EX must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_CONST
-    #error "JSON_HEDLEY_CONST must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_CONSTEXPR
-    #error "JSON_HEDLEY_CONSTEXPR must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_CONST_CAST
-    #error "JSON_HEDLEY_CONST_CAST must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_CPP_CAST
-    #error "JSON_HEDLEY_CPP_CAST must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_CRAY_VERSION
-    #error "JSON_HEDLEY_CRAY_VERSION must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_CRAY_VERSION_CHECK
-    #error "JSON_HEDLEY_CRAY_VERSION_CHECK must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_C_DECL
-    #error "JSON_HEDLEY_C_DECL must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_DEPRECATED
-    #error "JSON_HEDLEY_DEPRECATED must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_DEPRECATED_FOR
-    #error "JSON_HEDLEY_DEPRECATED_FOR must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_DIAGNOSTIC_DISABLE_CAST_QUAL
-    #error "JSON_HEDLEY_DIAGNOSTIC_DISABLE_CAST_QUAL must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_DIAGNOSTIC_DISABLE_CPP98_COMPAT_WRAP_
-    #error "JSON_HEDLEY_DIAGNOSTIC_DISABLE_CPP98_COMPAT_WRAP_ must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_DIAGNOSTIC_DISABLE_DEPRECATED
-    #error "JSON_HEDLEY_DIAGNOSTIC_DISABLE_DEPRECATED must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_DIAGNOSTIC_DISABLE_UNKNOWN_CPP_ATTRIBUTES
-    #error "JSON_HEDLEY_DIAGNOSTIC_DISABLE_UNKNOWN_CPP_ATTRIBUTES must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_DIAGNOSTIC_DISABLE_UNKNOWN_PRAGMAS
-    #error "JSON_HEDLEY_DIAGNOSTIC_DISABLE_UNKNOWN_PRAGMAS must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_DIAGNOSTIC_DISABLE_UNUSED_FUNCTION
-    #error "JSON_HEDLEY_DIAGNOSTIC_DISABLE_UNUSED_FUNCTION must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_DIAGNOSTIC_POP
-    #error "JSON_HEDLEY_DIAGNOSTIC_POP must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_DIAGNOSTIC_PUSH
-    #error "JSON_HEDLEY_DIAGNOSTIC_PUSH must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_DMC_VERSION
-    #error "JSON_HEDLEY_DMC_VERSION must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_DMC_VERSION_CHECK
-    #error "JSON_HEDLEY_DMC_VERSION_CHECK must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_EMPTY_BASES
-    #error "JSON_HEDLEY_EMPTY_BASES must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_EMSCRIPTEN_VERSION
-    #error "JSON_HEDLEY_EMSCRIPTEN_VERSION must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_EMSCRIPTEN_VERSION_CHECK
-    #error "JSON_HEDLEY_EMSCRIPTEN_VERSION_CHECK must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_END_C_DECLS
-    #error "JSON_HEDLEY_END_C_DECLS must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_FALL_THROUGH
-    #error "JSON_HEDLEY_FALL_THROUGH must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_FLAGS
-    #error "JSON_HEDLEY_FLAGS must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_FLAGS_CAST
-    #error "JSON_HEDLEY_FLAGS_CAST must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_GCC_HAS_ATTRIBUTE
-    #error "JSON_HEDLEY_GCC_HAS_ATTRIBUTE must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_GCC_HAS_BUILTIN
-    #error "JSON_HEDLEY_GCC_HAS_BUILTIN must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_GCC_HAS_CPP_ATTRIBUTE
-    #error "JSON_HEDLEY_GCC_HAS_CPP_ATTRIBUTE must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_GCC_HAS_DECLSPEC_ATTRIBUTE
-    #error "JSON_HEDLEY_GCC_HAS_DECLSPEC_ATTRIBUTE must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_GCC_HAS_EXTENSION
-    #error "JSON_HEDLEY_GCC_HAS_EXTENSION must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_GCC_HAS_FEATURE
-    #error "JSON_HEDLEY_GCC_HAS_FEATURE must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_GCC_HAS_WARNING
-    #error "JSON_HEDLEY_GCC_HAS_WARNING must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_GCC_NOT_CLANG_VERSION_CHECK
-    #error "JSON_HEDLEY_GCC_NOT_CLANG_VERSION_CHECK must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_GCC_VERSION
-    #error "JSON_HEDLEY_GCC_VERSION must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_GCC_VERSION_CHECK
-    #error "JSON_HEDLEY_GCC_VERSION_CHECK must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_GNUC_HAS_ATTRIBUTE
-    #error "JSON_HEDLEY_GNUC_HAS_ATTRIBUTE must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_GNUC_HAS_BUILTIN
-    #error "JSON_HEDLEY_GNUC_HAS_BUILTIN must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_GNUC_HAS_CPP_ATTRIBUTE
-    #error "JSON_HEDLEY_GNUC_HAS_CPP_ATTRIBUTE must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_GNUC_HAS_DECLSPEC_ATTRIBUTE
-    #error "JSON_HEDLEY_GNUC_HAS_DECLSPEC_ATTRIBUTE must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_GNUC_HAS_EXTENSION
-    #error "JSON_HEDLEY_GNUC_HAS_EXTENSION must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_GNUC_HAS_FEATURE
-    #error "JSON_HEDLEY_GNUC_HAS_FEATURE must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_GNUC_HAS_WARNING
-    #error "JSON_HEDLEY_GNUC_HAS_WARNING must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_GNUC_VERSION
-    #error "JSON_HEDLEY_GNUC_VERSION must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_GNUC_VERSION_CHECK
-    #error "JSON_HEDLEY_GNUC_VERSION_CHECK must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_HAS_ATTRIBUTE
-    #error "JSON_HEDLEY_HAS_ATTRIBUTE must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_HAS_BUILTIN
-    #error "JSON_HEDLEY_HAS_BUILTIN must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_HAS_CPP_ATTRIBUTE
-    #error "JSON_HEDLEY_HAS_CPP_ATTRIBUTE must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_HAS_CPP_ATTRIBUTE_NS
-    #error "JSON_HEDLEY_HAS_CPP_ATTRIBUTE_NS must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_HAS_DECLSPEC_ATTRIBUTE
-    #error "JSON_HEDLEY_HAS_DECLSPEC_ATTRIBUTE must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_HAS_EXTENSION
-    #error "JSON_HEDLEY_HAS_EXTENSION must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_HAS_FEATURE
-    #error "JSON_HEDLEY_HAS_FEATURE must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_HAS_WARNING
-    #error "JSON_HEDLEY_HAS_WARNING must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_IAR_VERSION
-    #error "JSON_HEDLEY_IAR_VERSION must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_IAR_VERSION_CHECK
-    #error "JSON_HEDLEY_IAR_VERSION_CHECK must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_IBM_VERSION
-    #error "JSON_HEDLEY_IBM_VERSION must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_IBM_VERSION_CHECK
-    #error "JSON_HEDLEY_IBM_VERSION_CHECK must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_IMPORT
-    #error "JSON_HEDLEY_IMPORT must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_INLINE
-    #error "JSON_HEDLEY_INLINE must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_INTEL_CL_VERSION
-    #error "JSON_HEDLEY_INTEL_CL_VERSION must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_INTEL_CL_VERSION_CHECK
-    #error "JSON_HEDLEY_INTEL_CL_VERSION_CHECK must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_INTEL_VERSION
-    #error "JSON_HEDLEY_INTEL_VERSION must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_INTEL_VERSION_CHECK
-    #error "JSON_HEDLEY_INTEL_VERSION_CHECK must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_IS_CONSTANT
-    #error "JSON_HEDLEY_IS_CONSTANT must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_IS_CONSTEXPR_
-    #error "JSON_HEDLEY_IS_CONSTEXPR_ must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_LIKELY
-    #error "JSON_HEDLEY_LIKELY must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_MALLOC
-    #error "JSON_HEDLEY_MALLOC must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_MCST_LCC_VERSION
-    #error "JSON_HEDLEY_MCST_LCC_VERSION must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_MCST_LCC_VERSION_CHECK
-    #error "JSON_HEDLEY_MCST_LCC_VERSION_CHECK must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_MESSAGE
-    #error "JSON_HEDLEY_MESSAGE must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_MSVC_VERSION
-    #error "JSON_HEDLEY_MSVC_VERSION must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_MSVC_VERSION_CHECK
-    #error "JSON_HEDLEY_MSVC_VERSION_CHECK must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_NEVER_INLINE
-    #error "JSON_HEDLEY_NEVER_INLINE must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_NON_NULL
-    #error "JSON_HEDLEY_NON_NULL must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_NO_ESCAPE
-    #error "JSON_HEDLEY_NO_ESCAPE must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_NO_RETURN
-    #error "JSON_HEDLEY_NO_RETURN must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_NO_THROW
-    #error "JSON_HEDLEY_NO_THROW must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_NULL
-    #error "JSON_HEDLEY_NULL must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_PELLES_VERSION
-    #error "JSON_HEDLEY_PELLES_VERSION must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_PELLES_VERSION_CHECK
-    #error "JSON_HEDLEY_PELLES_VERSION_CHECK must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_PGI_VERSION
-    #error "JSON_HEDLEY_PGI_VERSION must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_PGI_VERSION_CHECK
-    #error "JSON_HEDLEY_PGI_VERSION_CHECK must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_PRAGMA
-    #error "JSON_HEDLEY_PRAGMA must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_PREDICT
-    #error "JSON_HEDLEY_PREDICT must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_PREDICT_FALSE
-    #error "JSON_HEDLEY_PREDICT_FALSE must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_PREDICT_TRUE
-    #error "JSON_HEDLEY_PREDICT_TRUE must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_PRINTF_FORMAT
-    #error "JSON_HEDLEY_PRINTF_FORMAT must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_PRIVATE
-    #error "JSON_HEDLEY_PRIVATE must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_PUBLIC
-    #error "JSON_HEDLEY_PUBLIC must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_PURE
-    #error "JSON_HEDLEY_PURE must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_REINTERPRET_CAST
-    #error "JSON_HEDLEY_REINTERPRET_CAST must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_REQUIRE
-    #error "JSON_HEDLEY_REQUIRE must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_REQUIRE_CONSTEXPR
-    #error "JSON_HEDLEY_REQUIRE_CONSTEXPR must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_REQUIRE_MSG
-    #error "JSON_HEDLEY_REQUIRE_MSG must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_RESTRICT
-    #error "JSON_HEDLEY_RESTRICT must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_RETURNS_NON_NULL
-    #error "JSON_HEDLEY_RETURNS_NON_NULL must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_SENTINEL
-    #error "JSON_HEDLEY_SENTINEL must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_STATIC_ASSERT
-    #error "JSON_HEDLEY_STATIC_ASSERT must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_STATIC_CAST
-    #error "JSON_HEDLEY_STATIC_CAST must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_STRINGIFY
-    #error "JSON_HEDLEY_STRINGIFY must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_STRINGIFY_EX
-    #error "JSON_HEDLEY_STRINGIFY_EX must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_SUNPRO_VERSION
-    #error "JSON_HEDLEY_SUNPRO_VERSION must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_SUNPRO_VERSION_CHECK
-    #error "JSON_HEDLEY_SUNPRO_VERSION_CHECK must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_TINYC_VERSION
-    #error "JSON_HEDLEY_TINYC_VERSION must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_TINYC_VERSION_CHECK
-    #error "JSON_HEDLEY_TINYC_VERSION_CHECK must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_TI_ARMCL_VERSION
-    #error "JSON_HEDLEY_TI_ARMCL_VERSION must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_TI_ARMCL_VERSION_CHECK
-    #error "JSON_HEDLEY_TI_ARMCL_VERSION_CHECK must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_TI_CL2000_VERSION
-    #error "JSON_HEDLEY_TI_CL2000_VERSION must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_TI_CL2000_VERSION_CHECK
-    #error "JSON_HEDLEY_TI_CL2000_VERSION_CHECK must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_TI_CL430_VERSION
-    #error "JSON_HEDLEY_TI_CL430_VERSION must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_TI_CL430_VERSION_CHECK
-    #error "JSON_HEDLEY_TI_CL430_VERSION_CHECK must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_TI_CL6X_VERSION
-    #error "JSON_HEDLEY_TI_CL6X_VERSION must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_TI_CL6X_VERSION_CHECK
-    #error "JSON_HEDLEY_TI_CL6X_VERSION_CHECK must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_TI_CL7X_VERSION
-    #error "JSON_HEDLEY_TI_CL7X_VERSION must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_TI_CL7X_VERSION_CHECK
-    #error "JSON_HEDLEY_TI_CL7X_VERSION_CHECK must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_TI_CLPRU_VERSION
-    #error "JSON_HEDLEY_TI_CLPRU_VERSION must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_TI_CLPRU_VERSION_CHECK
-    #error "JSON_HEDLEY_TI_CLPRU_VERSION_CHECK must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_TI_VERSION
-    #error "JSON_HEDLEY_TI_VERSION must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_TI_VERSION_CHECK
-    #error "JSON_HEDLEY_TI_VERSION_CHECK must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_UNAVAILABLE
-    #error "JSON_HEDLEY_UNAVAILABLE must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_UNLIKELY
-    #error "JSON_HEDLEY_UNLIKELY must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_UNPREDICTABLE
-    #error "JSON_HEDLEY_UNPREDICTABLE must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_UNREACHABLE
-    #error "JSON_HEDLEY_UNREACHABLE must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_UNREACHABLE_RETURN
-    #error "JSON_HEDLEY_UNREACHABLE_RETURN must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_VERSION
-    #error "JSON_HEDLEY_VERSION must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_VERSION_DECODE_MAJOR
-    #error "JSON_HEDLEY_VERSION_DECODE_MAJOR must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_VERSION_DECODE_MINOR
-    #error "JSON_HEDLEY_VERSION_DECODE_MINOR must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_VERSION_DECODE_REVISION
-    #error "JSON_HEDLEY_VERSION_DECODE_REVISION must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_VERSION_ENCODE
-    #error "JSON_HEDLEY_VERSION_ENCODE must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_WARNING
-    #error "JSON_HEDLEY_WARNING must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_WARN_UNUSED_RESULT
-    #error "JSON_HEDLEY_WARN_UNUSED_RESULT must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_WARN_UNUSED_RESULT_MSG
-    #error "JSON_HEDLEY_WARN_UNUSED_RESULT_MSG must not remain defined after including json.hpp"
-#endif
-
-TEST_CASE("no JSON_HEDLEY_* macro leaks after including json.hpp")
-{
-    // if this test compiles at all, none of the JSON_HEDLEY_* macros checked
-    // above remained defined after including <nlohmann/json.hpp>
-    CHECK(true);
-}

tests/src/unit-ubjson.cpp

@@ -2149,6 +2149,111 @@ TEST_CASE("UBJSON")
     }
 }
 
+TEST_CASE("issue #5405 - array reserve for definite-length UBJSON arrays")
+{
+#if !defined(JSON_NOEXCEPTION)
+    // this SECTION relies on catching a thrown exception to distinguish
+    // which of two acceptable, bounded rejections a hostile header took;
+    // under JSON_NOEXCEPTION, JSON_THROW never produces a catchable C++
+    // exception (it aborts instead), so this cannot be tested that way here
+    SECTION("a huge claimed length with no element data must not over-allocate")
+    {
+        // optimized form [$type#count: type 'i' (int8), count as a four-byte
+        // 'l' (int32) of 0x7FFFFFFF (2147483647), but no element data at all.
+        // max_size() for a std::vector is far larger than this count, so it
+        // does not reject the header outright; the (capped) reservation must
+        // not attempt to allocate space for billions of elements before the
+        // missing data is detected.
+        json _;
+        const std::vector<uint8_t> input = {'[', '$', 'i', '#', 'l', 0x7F, 0xFF, 0xFF, 0xFF};
+        // On a platform where std::vector<json>::max_size() is smaller than
+        // the claimed count (e.g. 32-bit, where max_size() is bounded by a
+        // 32-bit SIZE_MAX divided by sizeof(json)), the SAX consumer's own
+        // check rejects the header outright (out_of_range.408, with the
+        // claimed count in the message) instead of accepting it and only
+        // finding it short of data once the (capped) reservation looks for
+        // element bytes that were never provided (parse_error.110). Either
+        // is an acceptable, bounded rejection of the hostile header -- the
+        // property under test is that no path attempts to allocate space
+        // for billions of elements.
+        bool threw = false;
+        try
+        {
+            _ = json::from_ubjson(input);
+        }
+        catch (const json::parse_error& e)
+        {
+            threw = true;
+            CHECK(e.id == 110);
+            CHECK(std::string(e.what()) == "[json.exception.parse_error.110] parse error at byte 10: syntax error while parsing UBJSON number: unexpected end of input");
+        }
+        catch (const json::out_of_range& e)
+        {
+            threw = true;
+            CHECK(e.id == 408);
+            CHECK(std::string(e.what()).find("excessive array size") != std::string::npos);
+        }
+        CHECK(threw);
+
+        // json_sax_dom_parser::start_array()'s max_size() check (unlike the
+        // scanner's own parse_error path) throws unconditionally via
+        // JSON_THROW rather than going through sax->parse_error(), so it is
+        // not gated by allow_exceptions=false on a platform where this
+        // header hits that check (e.g. 32-bit, see above) -- allow either
+        // a discarded result or the same out_of_range it throws with
+        // exceptions enabled.
+        try
+        {
+            CHECK(json::from_ubjson(input, true, false).is_discarded());
+        }
+        catch (const json::out_of_range& e)
+        {
+            CHECK(e.id == 408);
+        }
+    }
+#endif
+
+    SECTION("arrays of various sizes decode to the same value as before the reserve optimization")
+    {
+        for (const auto size :
+                {
+                    std::size_t{0}, std::size_t{1}, std::size_t{5}, // small
+                    std::size_t{16384},                             // exactly at the reserve cap
+                    std::size_t{20000}                              // above the reserve cap
+                })
+        {
+            CAPTURE(size)
+            json j = json::array();
+            for (std::size_t i = 0; i < size; ++i)
+            {
+                j.push_back(static_cast<int>(i % 1000));
+            }
+
+            // exercise both the plain and the optimized [$type#count encoding
+            const auto packed_plain = json::to_ubjson(j);
+            CHECK(json::from_ubjson(packed_plain) == j);
+
+            const auto packed_optimized = json::to_ubjson(j, true, true);
+            CHECK(json::from_ubjson(packed_optimized) == j);
+        }
+    }
+
+    SECTION("a user-defined SAX consumer is unaffected by the internal DOM reserve optimization")
+    {
+        // the reserve() call is local to json_sax_dom_parser / json_sax_dom_callback_parser;
+        // a custom SAX consumer that does not touch a DOM array sees identical events
+        json j = json::array();
+        for (int i = 0; i < 100; ++i)
+        {
+            j.push_back(i);
+        }
+        const auto packed = json::to_ubjson(j, true, true);
+
+        SaxCountdown scp(1000000); // large enough to never trigger an abort
+        CHECK(json::sax_parse(packed, &scp, json::input_format_t::ubjson));
+    }
+}
+
 TEST_CASE("Universal Binary JSON Specification Examples 1")
 {
     SECTION("Null Value")