Tests: skip the parse() allocation sweep with MSVC iterator debugging

With _ITERATOR_DEBUG_LEVEL > 0 (MSVC STL debug builds, clang-cl), containers
allocate inside noexcept functions, so a failing allocation terminates the
program: "test case CRASHED: Terminate handler called" in the sax_parse
subcase of #5985. The sweep test of #6000 has the same guard.

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

include/nlohmann/detail/input/binary_reader.hpp

@@ -344,8 +344,8 @@ class binary_reader
     nested document could declare a length that disagrees with where its
     terminator actually falls and quietly hand the bytes in between to the
     enclosing document. A well-formed document is at least 5 bytes (the prefix
-    plus the terminator); open_bson_document() rejects a smaller size before
+    plus the terminator); the equality also rejects those impossible sizes,
-    it is stored, so @a document_size is never negative here.
+    since at least 5 bytes are always consumed.
 
     @param[in] document_start  value of chars_read before the size prefix
     @param[in] document_size   the declared document size
@@ -353,7 +353,7 @@ class binary_reader
     */
     bool check_bson_document_size(const std::size_t document_start, const std::int32_t document_size)
     {
-        if (JSON_HEDLEY_UNLIKELY(static_cast<std::size_t>(document_size) != chars_read - document_start))
+        if (JSON_HEDLEY_UNLIKELY(document_size < 0 || static_cast<std::size_t>(document_size) != chars_read - document_start))
         {
             return bson_document_size_error(document_size, chars_read - document_start);
         }
@@ -3091,6 +3091,8 @@ class binary_reader
         if (size_and_type.first != npos)
         {
             if (size_and_type.second != 0)
+            {
+                if (size_and_type.second != 'N')
                 {
                     for (std::size_t i = 0; i < size_and_type.first; ++i)
                     {
@@ -3101,6 +3103,7 @@ class binary_reader
                         dim.push_back(dimlen);
                     }
                 }
+            }
             else
             {
                 for (std::size_t i = 0; i < size_and_type.first; ++i)
@@ -3300,9 +3303,11 @@ class binary_reader
                     // follow the documented _ArrayType_, _ArraySize_, _ArrayData_ order
                     if (ndarray_dtype != 0)
                     {
-                        // every optimized type marker is_valid_optimized_type() accepts for BJData has a name
                         const char* type_name = bjd_type_name(ndarray_dtype);
-                        JSON_ASSERT(type_name != nullptr);
+                        if (JSON_HEDLEY_UNLIKELY(type_name == nullptr))
+                        {
+                            return unexpected_byte("invalid byte", "type");
+                        }
 
                         string_t type_key = "_ArrayType_";
                         string_t type = type_name; // sax->string() takes a reference
@@ -3385,6 +3390,12 @@ class binary_reader
         if (current == '$')
         {
             result.second = get();  // must not ignore 'N', because 'N' maybe the type
+            if (input_format == input_format_t::bjdata
+                    && JSON_HEDLEY_UNLIKELY(is_bjd_excluded_optimized_type(result.second)))
+            {
+                return optimized_type_error();
+            }
+
             if (JSON_HEDLEY_UNLIKELY(!unexpect_eof("type")))
             {
                 return false;
@@ -3412,7 +3423,7 @@ class binary_reader
             // an ndarray was read here only if the flag flipped; when it was
             // seeded true, get_ubjson_size_value() already rejected the nested
             // dimension vector
-            if (is_ndarray && !inside_ndarray)
+            if (input_format == input_format_t::bjdata && is_ndarray && !inside_ndarray)
             {
                 result.second |= (1 << 8); // use bit 8 to indicate ndarray, all UBJSON and BJData markers should be ASCII letters
             }
@@ -3422,7 +3433,7 @@ class binary_reader
         if (current == '#')
         {
             const bool is_error = get_ubjson_size_value(result.first, is_ndarray);
-            if (is_ndarray && !inside_ndarray)
+            if (input_format == input_format_t::bjdata && is_ndarray && !inside_ndarray)
             {
                 return last_byte_error(exception_id::unexpected_byte, "ndarray requires both type and size", "size");
             }
@@ -3596,6 +3607,7 @@ class binary_reader
     JSON_HEDLEY_NEVER_INLINE
     bool parse_ubjson_typed_run(std::size_t& remaining, const char_int_type type, std::true_type /*bulk*/)
     {
+        const bool bjdata = input_format == input_format_t::bjdata;
         switch (type)
         {
             case 'U':
@@ -3609,11 +3621,11 @@ class binary_reader
             case 'L':
                 return parse_ubjson_typed_run<std::int64_t>(remaining);
             case 'u':
-                return parse_ubjson_typed_run<std::uint16_t>(remaining);
+                return !bjdata || parse_ubjson_typed_run<std::uint16_t>(remaining);
             case 'm':
-                return parse_ubjson_typed_run<std::uint32_t>(remaining);
+                return !bjdata || parse_ubjson_typed_run<std::uint32_t>(remaining);
             case 'M':
-                return parse_ubjson_typed_run<std::uint64_t>(remaining);
+                return !bjdata || parse_ubjson_typed_run<std::uint64_t>(remaining);
             case 'd':
                 return parse_ubjson_typed_run<float>(remaining);
             case 'D':
@@ -3694,7 +3706,7 @@ class binary_reader
         // if bit-8 of size_and_type.second is set to 1, encode bjdata ndarray as an object in JData annotated array format (https://github.com/NeuroJSON/jdata):
         // {"_ArrayType_" : "typeid", "_ArraySize_" : [n1, n2, ...], "_ArrayData_" : [v1, v2, ...]}
 
-        if ((size_and_type.second & (1 << 8)) != 0)
+        if (input_format == input_format_t::bjdata && size_and_type.first != npos && (size_and_type.second & (1 << 8)) != 0)
         {
             size_and_type.second &= ~(static_cast<char_int_type>(1) << 8);  // use bit 8 to indicate ndarray, here we remove the bit to restore the type marker
 
@@ -3753,7 +3765,7 @@ class binary_reader
         }
 
         // If BJData type marker is 'B' decode as binary
-        if (size_and_type.first != npos && size_and_type.second == 'B')
+        if (input_format == input_format_t::bjdata && size_and_type.first != npos && size_and_type.second == 'B')
         {
             binary_t result;
             return get_binary(size_and_type.first, result) && sax->binary(result);
@@ -3802,7 +3814,7 @@ class binary_reader
         }
 
         // do not accept ND-array size in objects in BJData
-        if ((size_and_type.second & (1 << 8)) != 0)
+        if (input_format == input_format_t::bjdata && size_and_type.first != npos && (size_and_type.second & (1 << 8)) != 0)
         {
             return last_byte_error(exception_id::unexpected_byte, "BJData object does not support ND-array size in optimized format", "object");
         }
@@ -5083,9 +5095,8 @@ class binary_reader
   JSON_PRIVATE_UNLESS_TESTED:
     /*!
     @brief check whether @a marker is a type marker that may follow '$'
-    UBJSON: Z N T F i U I l L d D H C S [ {; BJData: the numeric markers and C.
+    UBJSON: Z N T F i U I l L d D H C S [ {; BJData: the numeric markers and C
-    The markers BJData excludes (F H N S T Z [ {) are the ones
+    (BJData's excluded markers are rejected separately).
-    binary_writer::is_bjdata_excluded_type_marker() lists; keep the two in sync.
     */
     bool is_valid_optimized_type(const char_int_type marker) const noexcept
     {
@@ -5120,6 +5131,20 @@ class binary_reader
         }
     }
 
+    /*!
+    @brief whether @a marker is excluded from BJData's optimized ND-array types
+    @return whether @a marker is one of 'F', 'H', 'N', 'S', 'T', 'Z', '[', '{'
+
+    Mirrors binary_writer's @ref binary_writer::is_bjdata_excluded_type_marker
+    "is_bjdata_excluded_type_marker()`, which encodes the same list the other
+    way; keep the two in sync.
+    */
+    static constexpr bool is_bjd_excluded_optimized_type(const char_int_type marker) noexcept
+    {
+        return marker == '[' || marker == '{' || marker == 'S' || marker == 'H'
+               || marker == 'T' || marker == 'F' || marker == 'N' || marker == 'Z';
+    }
+
     /*!
     @brief look up the ND-array element type name for a BJData dtype marker
     @return the type name ("uint8", "int8", ...), or nullptr if @a marker does

include/nlohmann/detail/output/binary_writer.hpp

@@ -3126,19 +3126,22 @@ class binary_writer
                 // negative fixnum
                 write_number(static_cast<std::int8_t>(j.m_data.m_value.number_integer));
             }
-            else if (j.m_data.m_value.number_integer >= (std::numeric_limits<std::int8_t>::min)())
+            else if (j.m_data.m_value.number_integer >= (std::numeric_limits<std::int8_t>::min)() &&
+                     j.m_data.m_value.number_integer <= (std::numeric_limits<std::int8_t>::max)())
             {
                 // int 8
                 oa.write_character(to_char_type(0xD0));
                 write_number(static_cast<std::int8_t>(j.m_data.m_value.number_integer));
             }
-            else if (j.m_data.m_value.number_integer >= (std::numeric_limits<std::int16_t>::min)())
+            else if (j.m_data.m_value.number_integer >= (std::numeric_limits<std::int16_t>::min)() &&
+                     j.m_data.m_value.number_integer <= (std::numeric_limits<std::int16_t>::max)())
             {
                 // int 16
                 oa.write_character(to_char_type(0xD1));
                 write_number(static_cast<std::int16_t>(j.m_data.m_value.number_integer));
             }
-            else if (j.m_data.m_value.number_integer >= (std::numeric_limits<std::int32_t>::min)())
+            else if (j.m_data.m_value.number_integer >= (std::numeric_limits<std::int32_t>::min)() &&
+                     j.m_data.m_value.number_integer <= (std::numeric_limits<std::int32_t>::max)())
             {
                 // int 32
                 oa.write_character(to_char_type(0xD2));
@@ -4054,7 +4057,7 @@ class binary_writer
     Containers, strings, high-precision numbers, booleans and null cannot be
     declared as the single type of an optimized container in BJData; such a
     container is written unoptimized. The reader rejects them with the same
-    list (binary_reader::is_valid_optimized_type()).
+    list (binary_reader::is_bjd_excluded_optimized_type()).
     */
     static constexpr bool is_bjdata_excluded_type_marker(const CharType marker) noexcept
     {

include/nlohmann/detail/view/builder.hpp

@@ -1168,20 +1168,19 @@ indent_done:
             if (negative)
             {
                 ++p;
-                if (NLOHMANN_VIEW_UNLIKELY(cur() < '0' || cur() > '9'))
-                {
-                    return fail(error_code::number_after_minus);
-                }
             }
             const unsigned char* const int_start = p;
             if (cur() == '0')
             {
                 ++p;
             }
+            else if (NLOHMANN_VIEW_LIKELY(cur() >= '1' && cur() <= '9'))
+            {
+                p = skip_digits(p + 1, e);
+            }
             else
             {
-                // (a digit: the dispatch or the check after the sign saw it)
+                return fail(error_code::number_after_minus);
-                p = skip_digits(p + 1, e);
             }
             const auto int_digits = static_cast<std::size_t>(p - int_start);
             std::size_t frac_digits = 0;

single_include/nlohmann/json.hpp

@@ -18359,8 +18359,8 @@ class binary_reader
     nested document could declare a length that disagrees with where its
     terminator actually falls and quietly hand the bytes in between to the
     enclosing document. A well-formed document is at least 5 bytes (the prefix
-    plus the terminator); open_bson_document() rejects a smaller size before
+    plus the terminator); the equality also rejects those impossible sizes,
-    it is stored, so @a document_size is never negative here.
+    since at least 5 bytes are always consumed.
 
     @param[in] document_start  value of chars_read before the size prefix
     @param[in] document_size   the declared document size
@@ -18368,7 +18368,7 @@ class binary_reader
     */
     bool check_bson_document_size(const std::size_t document_start, const std::int32_t document_size)
     {
-        if (JSON_HEDLEY_UNLIKELY(static_cast<std::size_t>(document_size) != chars_read - document_start))
+        if (JSON_HEDLEY_UNLIKELY(document_size < 0 || static_cast<std::size_t>(document_size) != chars_read - document_start))
         {
             return bson_document_size_error(document_size, chars_read - document_start);
         }
@@ -21106,6 +21106,8 @@ class binary_reader
         if (size_and_type.first != npos)
         {
             if (size_and_type.second != 0)
+            {
+                if (size_and_type.second != 'N')
                 {
                     for (std::size_t i = 0; i < size_and_type.first; ++i)
                     {
@@ -21116,6 +21118,7 @@ class binary_reader
                         dim.push_back(dimlen);
                     }
                 }
+            }
             else
             {
                 for (std::size_t i = 0; i < size_and_type.first; ++i)
@@ -21315,9 +21318,11 @@ class binary_reader
                     // follow the documented _ArrayType_, _ArraySize_, _ArrayData_ order
                     if (ndarray_dtype != 0)
                     {
-                        // every optimized type marker is_valid_optimized_type() accepts for BJData has a name
                         const char* type_name = bjd_type_name(ndarray_dtype);
-                        JSON_ASSERT(type_name != nullptr);
+                        if (JSON_HEDLEY_UNLIKELY(type_name == nullptr))
+                        {
+                            return unexpected_byte("invalid byte", "type");
+                        }
 
                         string_t type_key = "_ArrayType_";
                         string_t type = type_name; // sax->string() takes a reference
@@ -21400,6 +21405,12 @@ class binary_reader
         if (current == '$')
         {
             result.second = get();  // must not ignore 'N', because 'N' maybe the type
+            if (input_format == input_format_t::bjdata
+                    && JSON_HEDLEY_UNLIKELY(is_bjd_excluded_optimized_type(result.second)))
+            {
+                return optimized_type_error();
+            }
+
             if (JSON_HEDLEY_UNLIKELY(!unexpect_eof("type")))
             {
                 return false;
@@ -21427,7 +21438,7 @@ class binary_reader
             // an ndarray was read here only if the flag flipped; when it was
             // seeded true, get_ubjson_size_value() already rejected the nested
             // dimension vector
-            if (is_ndarray && !inside_ndarray)
+            if (input_format == input_format_t::bjdata && is_ndarray && !inside_ndarray)
             {
                 result.second |= (1 << 8); // use bit 8 to indicate ndarray, all UBJSON and BJData markers should be ASCII letters
             }
@@ -21437,7 +21448,7 @@ class binary_reader
         if (current == '#')
         {
             const bool is_error = get_ubjson_size_value(result.first, is_ndarray);
-            if (is_ndarray && !inside_ndarray)
+            if (input_format == input_format_t::bjdata && is_ndarray && !inside_ndarray)
             {
                 return last_byte_error(exception_id::unexpected_byte, "ndarray requires both type and size", "size");
             }
@@ -21611,6 +21622,7 @@ class binary_reader
     JSON_HEDLEY_NEVER_INLINE
     bool parse_ubjson_typed_run(std::size_t& remaining, const char_int_type type, std::true_type /*bulk*/)
     {
+        const bool bjdata = input_format == input_format_t::bjdata;
         switch (type)
         {
             case 'U':
@@ -21624,11 +21636,11 @@ class binary_reader
             case 'L':
                 return parse_ubjson_typed_run<std::int64_t>(remaining);
             case 'u':
-                return parse_ubjson_typed_run<std::uint16_t>(remaining);
+                return !bjdata || parse_ubjson_typed_run<std::uint16_t>(remaining);
             case 'm':
-                return parse_ubjson_typed_run<std::uint32_t>(remaining);
+                return !bjdata || parse_ubjson_typed_run<std::uint32_t>(remaining);
             case 'M':
-                return parse_ubjson_typed_run<std::uint64_t>(remaining);
+                return !bjdata || parse_ubjson_typed_run<std::uint64_t>(remaining);
             case 'd':
                 return parse_ubjson_typed_run<float>(remaining);
             case 'D':
@@ -21709,7 +21721,7 @@ class binary_reader
         // if bit-8 of size_and_type.second is set to 1, encode bjdata ndarray as an object in JData annotated array format (https://github.com/NeuroJSON/jdata):
         // {"_ArrayType_" : "typeid", "_ArraySize_" : [n1, n2, ...], "_ArrayData_" : [v1, v2, ...]}
 
-        if ((size_and_type.second & (1 << 8)) != 0)
+        if (input_format == input_format_t::bjdata && size_and_type.first != npos && (size_and_type.second & (1 << 8)) != 0)
         {
             size_and_type.second &= ~(static_cast<char_int_type>(1) << 8);  // use bit 8 to indicate ndarray, here we remove the bit to restore the type marker
 
@@ -21768,7 +21780,7 @@ class binary_reader
         }
 
         // If BJData type marker is 'B' decode as binary
-        if (size_and_type.first != npos && size_and_type.second == 'B')
+        if (input_format == input_format_t::bjdata && size_and_type.first != npos && size_and_type.second == 'B')
         {
             binary_t result;
             return get_binary(size_and_type.first, result) && sax->binary(result);
@@ -21817,7 +21829,7 @@ class binary_reader
         }
 
         // do not accept ND-array size in objects in BJData
-        if ((size_and_type.second & (1 << 8)) != 0)
+        if (input_format == input_format_t::bjdata && size_and_type.first != npos && (size_and_type.second & (1 << 8)) != 0)
         {
             return last_byte_error(exception_id::unexpected_byte, "BJData object does not support ND-array size in optimized format", "object");
         }
@@ -23098,9 +23110,8 @@ class binary_reader
   JSON_PRIVATE_UNLESS_TESTED:
     /*!
     @brief check whether @a marker is a type marker that may follow '$'
-    UBJSON: Z N T F i U I l L d D H C S [ {; BJData: the numeric markers and C.
+    UBJSON: Z N T F i U I l L d D H C S [ {; BJData: the numeric markers and C
-    The markers BJData excludes (F H N S T Z [ {) are the ones
+    (BJData's excluded markers are rejected separately).
-    binary_writer::is_bjdata_excluded_type_marker() lists; keep the two in sync.
     */
     bool is_valid_optimized_type(const char_int_type marker) const noexcept
     {
@@ -23135,6 +23146,20 @@ class binary_reader
         }
     }
 
+    /*!
+    @brief whether @a marker is excluded from BJData's optimized ND-array types
+    @return whether @a marker is one of 'F', 'H', 'N', 'S', 'T', 'Z', '[', '{'
+
+    Mirrors binary_writer's @ref binary_writer::is_bjdata_excluded_type_marker
+    "is_bjdata_excluded_type_marker()`, which encodes the same list the other
+    way; keep the two in sync.
+    */
+    static constexpr bool is_bjd_excluded_optimized_type(const char_int_type marker) noexcept
+    {
+        return marker == '[' || marker == '{' || marker == 'S' || marker == 'H'
+               || marker == 'T' || marker == 'F' || marker == 'N' || marker == 'Z';
+    }
+
     /*!
     @brief look up the ND-array element type name for a BJData dtype marker
     @return the type name ("uint8", "int8", ...), or nullptr if @a marker does
@@ -31085,19 +31110,22 @@ class binary_writer
                 // negative fixnum
                 write_number(static_cast<std::int8_t>(j.m_data.m_value.number_integer));
             }
-            else if (j.m_data.m_value.number_integer >= (std::numeric_limits<std::int8_t>::min)())
+            else if (j.m_data.m_value.number_integer >= (std::numeric_limits<std::int8_t>::min)() &&
+                     j.m_data.m_value.number_integer <= (std::numeric_limits<std::int8_t>::max)())
             {
                 // int 8
                 oa.write_character(to_char_type(0xD0));
                 write_number(static_cast<std::int8_t>(j.m_data.m_value.number_integer));
             }
-            else if (j.m_data.m_value.number_integer >= (std::numeric_limits<std::int16_t>::min)())
+            else if (j.m_data.m_value.number_integer >= (std::numeric_limits<std::int16_t>::min)() &&
+                     j.m_data.m_value.number_integer <= (std::numeric_limits<std::int16_t>::max)())
             {
                 // int 16
                 oa.write_character(to_char_type(0xD1));
                 write_number(static_cast<std::int16_t>(j.m_data.m_value.number_integer));
             }
-            else if (j.m_data.m_value.number_integer >= (std::numeric_limits<std::int32_t>::min)())
+            else if (j.m_data.m_value.number_integer >= (std::numeric_limits<std::int32_t>::min)() &&
+                     j.m_data.m_value.number_integer <= (std::numeric_limits<std::int32_t>::max)())
             {
                 // int 32
                 oa.write_character(to_char_type(0xD2));
@@ -32013,7 +32041,7 @@ class binary_writer
     Containers, strings, high-precision numbers, booleans and null cannot be
     declared as the single type of an optimized container in BJData; such a
     container is written unoptimized. The reader rejects them with the same
-    list (binary_reader::is_valid_optimized_type()).
+    list (binary_reader::is_bjd_excluded_optimized_type()).
     */
     static constexpr bool is_bjdata_excluded_type_marker(const CharType marker) noexcept
     {

single_include/nlohmann/json_view.hpp

@@ -2473,20 +2473,19 @@ indent_done:
             if (negative)
             {
                 ++p;
-                if (NLOHMANN_VIEW_UNLIKELY(cur() < '0' || cur() > '9'))
-                {
-                    return fail(error_code::number_after_minus);
-                }
             }
             const unsigned char* const int_start = p;
             if (cur() == '0')
             {
                 ++p;
             }
+            else if (NLOHMANN_VIEW_LIKELY(cur() >= '1' && cur() <= '9'))
+            {
+                p = skip_digits(p + 1, e);
+            }
             else
             {
-                // (a digit: the dispatch or the check after the sign saw it)
+                return fail(error_code::number_after_minus);
-                p = skip_digits(p + 1, e);
             }
             const auto int_digits = static_cast<std::size_t>(p - int_start);
             std::size_t frac_digits = 0;

tests/src/unit-allocator.cpp

@@ -1026,7 +1026,10 @@ TEST_CASE("insert() provides its documented exception guarantees (#5986)")
 }
 #endif
 
-#if !defined(JSON_NOEXCEPTION)
+// the no-exceptions CI job has no std::bad_alloc to catch; with iterator
+// debugging (MSVC STL debug builds) containers allocate inside noexcept
+// functions, so failing an allocation there terminates the program
+#if !defined(JSON_NOEXCEPTION) && !(defined(_ITERATOR_DEBUG_LEVEL) && _ITERATOR_DEBUG_LEVEL > 0)
 namespace
 {
 // the allocation numbered sweep_fail_at (counted from 1) throws; 0 never fails

tests/src/unit-bjdata.cpp

@@ -78,25 +78,23 @@ TEST_CASE("BJData")
 {
     SECTION("binary_reader BJData lookup tables")
     {
-        // bjd_type_name() is static; is_valid_optimized_type() needs a BJData reader
+        // both lookups are static member functions
         std::vector<std::uint8_t> const data;
         using reader_t = nlohmann::detail::binary_reader<json, decltype(nlohmann::detail::input_adapter(data))>;
 
-        // the markers BJData excludes as optimized types must match
+        // the excluded optimized-type markers must match binary_writer's
-        // binary_writer's is_bjdata_excluded_type_marker(), which encodes the
+        // is_bjdata_excluded_type_marker(), which encodes the same 8 markers
-        // same 8 markers
-        reader_t reader(nlohmann::detail::input_adapter(data), json::input_format_t::bjdata);
         for (const char marker :
-                {'[', '{', 'S', 'H', 'T', 'F', 'N', 'Z', 'x'
+                {'[', '{', 'S', 'H', 'T', 'F', 'N', 'Z'
                 })
         {
-            CHECK(!reader.is_valid_optimized_type(static_cast<unsigned char>(marker)));
+            CHECK(reader_t::is_bjd_excluded_optimized_type(static_cast<unsigned char>(marker)));
         }
         for (const char marker :
-                {'U', 'i', 'u', 'I', 'm', 'l', 'M', 'L', 'd', 'D', 'C', 'B', 'h'
+                {'U', 'i', 'u', 'I', 'm', 'l', 'M', 'L', 'd', 'D', 'C', 'B', 'x'
                 })
         {
-            CHECK(reader.is_valid_optimized_type(static_cast<unsigned char>(marker)));
+            CHECK(!reader_t::is_bjd_excluded_optimized_type(static_cast<unsigned char>(marker)));
         }
 
         // every dtype marker must round-trip to its ND-array type name

tests/src/unit-locale-cpp.cpp

@@ -505,8 +505,8 @@ struct locale_switching_token
 {
     using value_type = char;
 
-    locale_switching_token(std::string text_, std::string switch_to_)
+    locale_switching_token(std::string text_, const char* switch_to_)
-        : text(std::move(text_)), switch_to(std::move(switch_to_))
+        : text(std::move(text_)), switch_to(switch_to_)
     {}
 
     std::size_t size() const
@@ -523,13 +523,13 @@ struct locale_switching_token
     {
         if (!switched)
         {
-            switched = std::setlocale(LC_NUMERIC, switch_to.c_str()) != nullptr;
+            switched = std::setlocale(LC_NUMERIC, switch_to) != nullptr;
         }
         return &text[0];
     }
 
     std::string text;
-    std::string switch_to;
+    const char* switch_to;
     bool switched = false;
 };