Fix -Weffc++ errors in the #5198 locale test

GCC's -Weffc++ (an error in ci_test_gcc and ci_test_standards_gcc)
rejected LocaleSwitchingSax: it has a pointer data member but does not
declare its copy operations, and its vectors are not initialized in the
member initializer list. Store the locale name as a std::string and give
the vectors brace initializers, like SaxEventLogger in
unit-deserialization.cpp.

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

README.md

@@ -363,7 +363,7 @@ std::cout << j_string << " == " << serialized_string << std::endl;
 
 [`.dump()`](https://json.nlohmann.me/api/basic_json/dump/) returns the originally stored string value.
 
-Note the library only supports UTF-8. When you store strings with different encodings in the library, calling [`dump()`](https://json.nlohmann.me/api/basic_json/dump/) may throw an exception unless `json::error_handler_t::replace`, `json::error_handler_t::ignore`, or `json::error_handler_t::keep` are used as error handlers.
+Note the library only supports UTF-8. When you store strings with different encodings in the library, calling [`dump()`](https://json.nlohmann.me/api/basic_json/dump/) may throw an exception unless `json::error_handler_t::replace` or `json::error_handler_t::ignore` are used as error handlers.
 
 #### To/from streams (e.g., files, string streams)
 
@@ -1915,7 +1915,7 @@ The library supports **Unicode input** as follows:
 - [Unicode noncharacters](https://www.unicode.org/faq/private_use.html#nonchar1) will not be replaced by the library.
 - Invalid surrogates (e.g., incomplete pairs such as `\uDEAD`) will yield parse errors.
 - The strings stored in the library are UTF-8 encoded. When using the default string type (`std::string`), note that its length/size functions return the number of stored bytes rather than the number of characters or glyphs.
-- When you store strings with different encodings in the library, calling [`dump()`](https://json.nlohmann.me/api/basic_json/dump/) may throw an exception unless `json::error_handler_t::replace`, `json::error_handler_t::ignore`, or `json::error_handler_t::keep` are used as error handlers.
+- When you store strings with different encodings in the library, calling [`dump()`](https://json.nlohmann.me/api/basic_json/dump/) may throw an exception unless `json::error_handler_t::replace` or `json::error_handler_t::ignore` are used as error handlers.
 - To store wide strings (e.g., `std::wstring`), you need to convert them to a UTF-8 encoded `std::string` before, see [an example](https://json.nlohmann.me/home/faq/#wide-string-handling).
 
 ### Comments in JSON

docs/mkdocs/docs/api/basic_json/dump.md

@@ -25,15 +25,10 @@ and `ensure_ascii` parameters.
     result consists of ASCII characters only.
 
 `error_handler` (in)
-:   how to react on decoding errors; there are four possible values (see [`error_handler_t`](error_handler_t.md)):
-
-    - `strict`: throw a [`type_error`](../../home/exceptions.md#type-errors) exception in case a decoding error occurs
-      (default),
-    - `replace`: replace invalid UTF-8 sequences with U+FFFD (� REPLACEMENT CHARACTER),
-    - `ignore`: ignore invalid UTF-8 sequences during serialization; all valid bytes are copied to the output unchanged,
-      and invalid bytes are dropped, and
-    - `keep`: keep invalid UTF-8 sequences during serialization; all bytes are copied to the output unchanged, so the
-      result is not valid UTF-8.
+:   how to react on decoding errors; there are three possible values (see [`error_handler_t`](error_handler_t.md):
+    `strict` (throws an exception in case a decoding error occurs; default), `replace` (replace invalid UTF-8 sequences
+    with U+FFFD), and `ignore` (ignore invalid UTF-8 sequences during serialization; all valid bytes are copied to the
+    output unchanged, and invalid bytes are dropped)).
     
 ## Return value
 
@@ -99,4 +94,3 @@ Binary values are serialized as an object containing two keys:
 - Indentation character `indent_char`, option `ensure_ascii` and exceptions added in version 3.0.0.
 - Error handlers added in version 3.4.0.
 - Serialization of binary values added in version 3.8.0.
-- Error handler value `keep` added in version 3.13.0.

docs/mkdocs/docs/api/basic_json/error_handler_t.md

@@ -4,13 +4,12 @@
 enum class error_handler_t {
     strict,
     replace,
-    ignore,
-    keep
+    ignore
 };
 ```
 
 This enumeration is used in the [`dump`](dump.md) function to choose how to treat decoding errors while serializing a
-`basic_json` value. Four values are differentiated:
+`basic_json` value. Three values are differentiated:
 
 strict
 :   throw a `type_error` exception in case of invalid UTF-8
@@ -21,12 +20,6 @@ replace
 ignore
 :   ignore invalid UTF-8 sequences; all valid bytes are copied to the output unchanged, and invalid bytes are dropped
 
-keep
-:   keep invalid UTF-8 sequences; all bytes are copied to the output unchanged. Valid characters are still escaped as
-    usual (e.g., `"`, `\\`, and control characters), so the result has valid JSON syntax, but it is not valid UTF-8.
-    In particular, [`parse`](parse.md) rejects it, and with `ensure_ascii` set to `true`, the invalid bytes are the
-    only non-ASCII bytes of the output.
-
 ## Examples
 
 ??? example
@@ -47,4 +40,3 @@ keep
 ## Version history
 
 - Added in version 3.4.0.
-- Added value `keep` in version 3.13.0.

docs/mkdocs/docs/examples/error_handler_t.cpp

@@ -1,4 +1,3 @@
-#include <iomanip>
 #include <iostream>
 #include <nlohmann/json.hpp>
 
@@ -22,12 +21,4 @@ int main()
               << "\nstring with ignored invalid characters: "
               << j_invalid.dump(-1, ' ', false, json::error_handler_t::ignore)
               << '\n';
-
-    // the invalid byte is kept; print the result byte-wise to make it visible
-    std::cout << "string with kept invalid characters:";
-    for (const unsigned char c : j_invalid.dump(-1, ' ', false, json::error_handler_t::keep))
-    {
-        std::cout << ' ' << std::hex << std::setw(2) << std::setfill('0') << static_cast<int>(c);
-    }
-    std::cout << '\n';
 }

docs/mkdocs/docs/examples/error_handler_t.output

@@ -1,4 +1,3 @@
 [json.exception.type_error.316] invalid UTF-8 byte at index 2: 0xA9
 string with replaced invalid characters: "ä�ü"
 string with ignored invalid characters: "äü"
-string with kept invalid characters: 22 c3 a4 a9 c3 bc 22

docs/mkdocs/docs/features/serialization.md

@@ -64,7 +64,6 @@ serialization fails by default. The fourth argument of `dump` selects an
 - `strict` (default) — throw a [`type_error.316`](../home/exceptions.md#jsonexceptiontype_error316) exception.
 - `replace` — replace invalid bytes with the Unicode replacement character U+FFFD (`�`).
 - `ignore` — silently drop invalid bytes.
-- `keep` — copy invalid bytes to the output unchanged; the result is not valid UTF-8.
 
 ??? example
 

docs/mkdocs/docs/home/exceptions.md

@@ -755,7 +755,6 @@ The `dump()` function only works with UTF-8 encoded strings; that is, if you ass
     - Pass an error handler as last parameter to the `dump()` function to avoid this exception:
         - `json::error_handler_t::replace` will replace invalid bytes sequences with `U+FFFD` 
         - `json::error_handler_t::ignore` will silently ignore invalid byte sequences
-        - `json::error_handler_t::keep` will copy invalid byte sequences to the output unchanged
 
 ### json.exception.type_error.317
 

docs/mkdocs/docs/home/faq.md

@@ -85,7 +85,7 @@ The library supports **Unicode input** as follows:
 - The library will not replace [Unicode noncharacters](http://www.unicode.org/faq/private_use.html#nonchar1).
 - Invalid surrogates (e.g., incomplete pairs such as `\uDEAD`) will yield parse errors.
 - The strings stored in the library are UTF-8 encoded. When using the default string type (`std::string`), note that its length/size functions return the number of stored bytes rather than the number of characters or glyphs.
-- When you store strings with different encodings in the library, calling [`dump()`](https://nlohmann.github.io/json/classnlohmann_1_1basic__json_a50ec80b02d0f3f51130d4abb5d1cfdc5.html#a50ec80b02d0f3f51130d4abb5d1cfdc5) may throw an exception unless `json::error_handler_t::replace`, `json::error_handler_t::ignore`, or `json::error_handler_t::keep` are used as error handlers.
+- When you store strings with different encodings in the library, calling [`dump()`](https://nlohmann.github.io/json/classnlohmann_1_1basic__json_a50ec80b02d0f3f51130d4abb5d1cfdc5.html#a50ec80b02d0f3f51130d4abb5d1cfdc5) may throw an exception unless `json::error_handler_t::replace` or `json::error_handler_t::ignore` are used as error handlers.
 
 In most cases, the parser is right to complain, because the input is not UTF-8 encoded. This is especially true for Microsoft Windows, where Latin-1 or ISO 8859-1 is often the standard encoding.
 

include/nlohmann/detail/input/lexer.hpp

@@ -206,7 +206,6 @@ class lexer : public lexer_base<BasicJsonType>
     explicit lexer(InputAdapterType&& adapter, bool ignore_comments_ = false, bool discard_number_values_ = false) noexcept
         : ia(std::move(adapter))
         , ignore_comments(ignore_comments_)
-        , decimal_point_char(static_cast<char_int_type>(get_decimal_point()))
         , discard_number_values(discard_number_values_)
     {}
 
@@ -222,8 +221,7 @@ class lexer : public lexer_base<BasicJsonType>
     // locales
     /////////////////////
 
-    /// return the locale-dependent decimal point
-    JSON_HEDLEY_PURE
+    /// return the decimal point of the current locale
     static char get_decimal_point() noexcept
     {
         const auto* loc = localeconv();
@@ -1092,9 +1090,10 @@ class lexer : public lexer_base<BasicJsonType>
             token_type::value_float if number could be successfully scanned,
             token_type::parse_error otherwise
 
-    @note The scanner is independent of the current locale. Internally, the
-          locale's decimal point is used instead of `.` to work with the
-          locale-dependent converters.
+    @note The scanner is independent of the current locale: token_buffer
+          always holds `.`. Only the std::strtod fallback of convert_number()
+          depends on the locale, and it looks up the decimal point right
+          before converting (see convert_float_locale_aware()).
     */
     token_type scan_number()  // lgtm [cpp/use-of-goto] `goto` is used in this function to implement the number-parsing state machine described above. By design, any finite input will eventually reach the "done" state or return token_type::parse_error. In each intermediate state, 1 byte of the input is appended to the token_buffer vector, and only the already initialized variables token_buffer, number_type, and error_message are manipulated.
     {
@@ -1183,7 +1182,7 @@ scan_number_zero:
         {
             case '.':
             {
-                add(decimal_point_char);
+                add(current);
                 decimal_point_position = token_buffer.size() - 1;
                 goto scan_number_decimal1;
             }
@@ -1220,7 +1219,7 @@ scan_number_any1:
 
             case '.':
             {
-                add(decimal_point_char);
+                add(current);
                 decimal_point_position = token_buffer.size() - 1;
                 goto scan_number_decimal1;
             }
@@ -1462,9 +1461,9 @@ scan_number_done:
 
         // Only a number below 1 can carry further insignificant zeros, and only
         // while the count stays at the limit does removing them change the
-        // answer - so this loop is skipped for all but a few tokens. Note
-        // token_buffer holds the locale's decimal point, so the fraction is
-        // located through decimal_point_position rather than by searching '.'.
+        // answer - so this loop is skipped for all but a few tokens. The
+        // fraction is located through decimal_point_position rather than by
+        // searching '.'.
         if (lead_zero != 0)
         {
             JSON_ASSERT(has_dot != 0); // an integer "0" cannot reach the limit
@@ -1482,8 +1481,8 @@ scan_number_done:
     @brief convert the number text in token_buffer to its value and token type
 
     The digit sequence in token_buffer has already been validated (by the
-    scan_number() state machine or by the contiguous fast path) and holds the
-    locale decimal point in place of '.'. Integers are parsed first and fall
+    scan_number() state machine or by the contiguous fast path) and holds '.'
+    as decimal point, independent of the locale. Integers are parsed first and fall
     back to floating point on overflow. This is shared so both scanners produce
     identical results.
 
@@ -1563,7 +1562,7 @@ scan_number_done:
         // integer conversion above overflowed. Prefer std::from_chars
         // (Eisel-Lemire, locale-independent, correctly rounded) when available;
         // otherwise the exact Clinger fast path (double only); otherwise the
-        // locale-aware strtof/strtod.
+        // locale-aware strtof/strtod/strtold.
         if (parse_float_from_chars(num_begin, num_end, value_float))
         {
             return token_type::value_float;
@@ -1572,26 +1571,75 @@ scan_number_done:
         // extra pass over the token's bytes, which otherwise shows up on
         // high-precision inputs such as canada.json
         if (mantissa_fits_clinger(mantissa_end)
-                && parse_float_fast(num_begin, num_end, decimal_point_char, value_float))
+                && parse_float_fast(num_begin, num_end, value_float))
         {
             return token_type::value_float;
         }
 
-        char* endptr = nullptr; // NOLINT(misc-const-correctness,cppcoreguidelines-pro-type-vararg,hicpp-vararg)
-        strtof(value_float, token_buffer.data(), &endptr);
-
-        // we checked the number format before
-        JSON_ASSERT(endptr == token_buffer.data() + token_buffer.size());
-
+        convert_float_locale_aware();
         return token_type::value_float;
     }
 
+    /*!
+    @brief convert the float in token_buffer with strtof/strtod/strtold
+
+    These functions expect the decimal point of the *current* locale, so it is
+    looked up right before the conversion instead of once when the lexer is
+    constructed: a locale change in between (by a parser callback, a SAX
+    handler, or another thread) must not truncate the value (#5198). The
+    token has been validated before, so if the conversion stops early and the
+    decimal point changed in the meantime, the locale changed between the
+    lookup and the call, and the conversion is repeated with the new decimal
+    point. If the decimal point did not change, a retry cannot succeed: the
+    locale's decimal point is not a single character (e.g., the two-byte
+    U+066B of ar_EG.UTF-8 or fa_IR.UTF-8) and cannot be substituted in place.
+    The value strtod parsed up to that point is kept, as before this change.
+
+    Note that changing the locale in another thread *while* strtod runs is
+    undefined behavior of the C library, which this function cannot prevent.
+    */
+    void convert_float_locale_aware()
+    {
+        const bool has_dot = decimal_point_position != std::string::npos;
+        char decimal_point = get_decimal_point();
+        for (;;)
+        {
+            const bool substitute = has_dot && decimal_point != '.';
+            if (substitute)
+            {
+                token_buffer[decimal_point_position] = static_cast<typename string_t::value_type>(decimal_point);
+            }
+
+            char* endptr = nullptr; // NOLINT(misc-const-correctness,cppcoreguidelines-pro-type-vararg,hicpp-vararg)
+            strtof(value_float, token_buffer.data(), &endptr);
+
+            if (substitute)
+            {
+                // get_string() hands the token to the SAX interface with '.'
+                token_buffer[decimal_point_position] = '.';
+            }
+
+            if (JSON_HEDLEY_LIKELY(endptr == token_buffer.data() + token_buffer.size()))
+            {
+                return;
+            }
+
+            // retry only if the locale changed; otherwise, this would loop forever
+            const char current_decimal_point = get_decimal_point();
+            if (current_decimal_point == decimal_point)
+            {
+                return;
+            }
+            decimal_point = current_decimal_point;
+        }
+    }
+
     /*!
     @brief contiguous fast path for scanning a number
 
     Parses the whole number token straight from the input buffer, avoiding the
     per-character get()/add() of scan_number(). On success it fills token_buffer
-    (with the locale decimal point substituted, as scan_number() does) and
+    (as scan_number() does) and
     returns the token type. On anything it does not fully recognize as a
     well-formed number it makes no state change and returns
     token_type::uninitialized, so the caller falls back to scan_number(), which
@@ -1707,16 +1755,11 @@ scan_number_done:
         }
 #endif
 
-        // materialize the token exactly as scan_number() would, substituting the
-        // locale decimal point so convert_number()'s strtof fallback stays valid.
-        // reset() already cleared token_buffer, so append() fills it (assign() is
-        // avoided because custom string_t types need not provide it)
+        // materialize the token exactly as scan_number() would. reset() already
+        // cleared token_buffer, so append() fills it (assign() is avoided
+        // because custom string_t types need not provide it)
         token_buffer.append(reinterpret_cast<const typename string_t::value_type*>(data), len);
-        if (dot_index != std::string::npos)
-        {
-            token_buffer[dot_index] = static_cast<typename string_t::value_type>(decimal_point_char);
-            decimal_point_position = dot_index;
-        }
+        decimal_point_position = dot_index;
 
         ia.bulk_skip(len - 1);
         position.chars_read_total += (len - 1);
@@ -1983,11 +2026,7 @@ scan_number_done:
     /// return current string value (implicitly resets the token; useful only once)
     string_t& get_string()
     {
-        // translate decimal points from locale back to '.' (#4084)
-        if (decimal_point_char != '.' && decimal_point_position != std::string::npos)
-        {
-            token_buffer[decimal_point_position] = '.';
-        }
+        // a number token holds '.' regardless of the locale (#4084)
         return token_buffer;
     }
 
@@ -2283,9 +2322,7 @@ scan_number_done:
     number_unsigned_t value_unsigned = 0;
     number_float_t value_float = 0;
 
-    /// the decimal point
-    const char_int_type decimal_point_char = '.';
-    /// the position of the decimal point in the input
+    /// the position of the decimal point in token_buffer
     std::size_t decimal_point_position = std::string::npos;
 
     /// whether the caller (e.g. accept()/json_sax_acceptor) only needs the

include/nlohmann/detail/input/number_parse.hpp

@@ -118,14 +118,12 @@ std::strtod. The parser only activates for number_float_t == double; float and
 long double keep the std::strtof/std::strtold paths (see the templated overload
 below).
 
-@param[in]  first          pointer to the first character of the number
-@param[in]  last           pointer past the last character
-@param[in]  decimal_point  the (locale-dependent) decimal point character
-@param[out] out            the parsed value on success
+@param[in]  first  pointer to the first character of the number
+@param[in]  last   pointer past the last character
+@param[out] out    the parsed value on success
 @return true if the value was parsed exactly; false to fall back to strtod
 */
-template<typename DecimalPointType>
-bool parse_float_fast(const char* first, const char* last, DecimalPointType decimal_point, double& out) noexcept
+inline bool parse_float_fast(const char* first, const char* last, double& out) noexcept
 {
 #if defined(FLT_EVAL_METHOD) && FLT_EVAL_METHOD != 0
     // Clinger's fast path is only exact when double operations are evaluated in
@@ -136,7 +134,6 @@ bool parse_float_fast(const char* first, const char* last, DecimalPointType deci
     // std::from_chars / std::strtod path.
     static_cast<void>(first);
     static_cast<void>(last);
-    static_cast<void>(decimal_point);
     static_cast<void>(out);
     return false;
 #else
@@ -175,7 +172,7 @@ bool parse_float_fast(const char* first, const char* last, DecimalPointType deci
             ++num_digits;
             fractional_digits += static_cast<int>(seen_dot);
         }
-        else if (static_cast<DecimalPointType>(c) == decimal_point)
+        else if (c == '.')
         {
             if (JSON_HEDLEY_UNLIKELY(seen_dot))
             {
@@ -260,8 +257,8 @@ bool parse_float_fast(const char* first, const char* last, DecimalPointType deci
 }
 
 /// fast float path is only exact for `double`; decline for float/long double
-template<typename DecimalPointType, typename FloatType>
-bool parse_float_fast(const char* /*first*/, const char* /*last*/, DecimalPointType /*decimal_point*/, FloatType& /*out*/) noexcept
+template<typename FloatType>
+bool parse_float_fast(const char* /*first*/, const char* /*last*/, FloatType& /*out*/) noexcept
 {
     return false;
 }
@@ -273,9 +270,7 @@ std::from_chars is locale-independent, correctly rounded, and - via the
 Eisel-Lemire algorithm in modern standard libraries - much faster than strtod
 over the whole value range (not just the Clinger subset). It is used only when
 __cpp_lib_to_chars indicates full floating-point support and only when it
-consumes the entire token ([first, last)); a partial parse means the buffer
-uses a non-'.' locale decimal point, in which case the caller falls back to the
-locale-aware path. An under-/overflow (result_out_of_range) also declines, so
+consumes the entire token ([first, last)). An under-/overflow (result_out_of_range) also declines, so
 the caller's strtod fallback supplies the well-defined ±inf/0 result the parser
 expects (side-stepping the P4168 divergence between implementations).
 

include/nlohmann/detail/output/serializer.hpp

@@ -48,8 +48,7 @@ enum class error_handler_t
 {
     strict,  ///< throw a type_error exception in case of invalid UTF-8
     replace, ///< replace invalid UTF-8 sequences with U+FFFD
-    ignore,  ///< ignore invalid UTF-8 sequences
-    keep     ///< keep invalid UTF-8 sequences; their bytes are copied unchanged
+    ignore   ///< ignore invalid UTF-8 sequences
 };
 
 template<typename BasicJsonType>
@@ -1020,47 +1019,6 @@ class serializer
                             break;
                         }
 
-                        case error_handler_t::keep:
-                        {
-                            // drop whatever the incomplete sequence left in
-                            // the buffer (only copied if !EnsureAscii) and copy
-                            // the ill-formed bytes from the input instead
-                            bytes = bytes_after_last_accept;
-
-                            if (undumped_chars > 0)
-                            {
-                                // the pending bytes of the incomplete sequence
-                                // are ill-formed; the current byte may be OK for
-                                // itself, so we would like to read it again
-                                for (std::size_t j = i - undumped_chars; j < i; ++j)
-                                {
-                                    string_buffer[bytes++] = s[j];
-                                }
-                                --i;
-                            }
-                            else
-                            {
-                                // the current byte cannot start any sequence
-                                string_buffer[bytes++] = s[i];
-                            }
-
-                            // write buffer and reset index; there must be 13 bytes
-                            // left, as this is the maximal number of bytes to be
-                            // written ("\uxxxx\uxxxx\0") for one code point
-                            if (string_buffer.size() - bytes < 13)
-                            {
-                                put_buffer(string_buffer, bytes);
-                                bytes = 0;
-                            }
-
-                            bytes_after_last_accept = bytes;
-                            undumped_chars = 0;
-
-                            // continue processing the string
-                            state = UTF8_ACCEPT;
-                            break;
-                        }
-
                         default:            // LCOV_EXCL_LINE
                             JSON_ASSERT(false); // NOLINT(cert-dcl03-c,hicpp-static-assert,misc-static-assert) LCOV_EXCL_LINE
                     }
@@ -1106,15 +1064,6 @@ class serializer
                     break;
                 }
 
-                case error_handler_t::keep:
-                {
-                    // write all accepted bytes
-                    put_buffer(string_buffer, bytes_after_last_accept);
-                    // copy the bytes of the incomplete sequence unchanged
-                    put_string(s, s.size() - undumped_chars, s.size());
-                    break;
-                }
-
                 case error_handler_t::replace:
                 {
                     // write all accepted bytes

single_include/nlohmann/json.hpp

@@ -8605,14 +8605,12 @@ std::strtod. The parser only activates for number_float_t == double; float and
 long double keep the std::strtof/std::strtold paths (see the templated overload
 below).
 
-@param[in]  first          pointer to the first character of the number
-@param[in]  last           pointer past the last character
-@param[in]  decimal_point  the (locale-dependent) decimal point character
-@param[out] out            the parsed value on success
+@param[in]  first  pointer to the first character of the number
+@param[in]  last   pointer past the last character
+@param[out] out    the parsed value on success
 @return true if the value was parsed exactly; false to fall back to strtod
 */
-template<typename DecimalPointType>
-bool parse_float_fast(const char* first, const char* last, DecimalPointType decimal_point, double& out) noexcept
+inline bool parse_float_fast(const char* first, const char* last, double& out) noexcept
 {
 #if defined(FLT_EVAL_METHOD) && FLT_EVAL_METHOD != 0
     // Clinger's fast path is only exact when double operations are evaluated in
@@ -8623,7 +8621,6 @@ bool parse_float_fast(const char* first, const char* last, DecimalPointType deci
     // std::from_chars / std::strtod path.
     static_cast<void>(first);
     static_cast<void>(last);
-    static_cast<void>(decimal_point);
     static_cast<void>(out);
     return false;
 #else
@@ -8662,7 +8659,7 @@ bool parse_float_fast(const char* first, const char* last, DecimalPointType deci
             ++num_digits;
             fractional_digits += static_cast<int>(seen_dot);
         }
-        else if (static_cast<DecimalPointType>(c) == decimal_point)
+        else if (c == '.')
         {
             if (JSON_HEDLEY_UNLIKELY(seen_dot))
             {
@@ -8747,8 +8744,8 @@ bool parse_float_fast(const char* first, const char* last, DecimalPointType deci
 }
 
 /// fast float path is only exact for `double`; decline for float/long double
-template<typename DecimalPointType, typename FloatType>
-bool parse_float_fast(const char* /*first*/, const char* /*last*/, DecimalPointType /*decimal_point*/, FloatType& /*out*/) noexcept
+template<typename FloatType>
+bool parse_float_fast(const char* /*first*/, const char* /*last*/, FloatType& /*out*/) noexcept
 {
     return false;
 }
@@ -8760,9 +8757,7 @@ std::from_chars is locale-independent, correctly rounded, and - via the
 Eisel-Lemire algorithm in modern standard libraries - much faster than strtod
 over the whole value range (not just the Clinger subset). It is used only when
 __cpp_lib_to_chars indicates full floating-point support and only when it
-consumes the entire token ([first, last)); a partial parse means the buffer
-uses a non-'.' locale decimal point, in which case the caller falls back to the
-locale-aware path. An under-/overflow (result_out_of_range) also declines, so
+consumes the entire token ([first, last)). An under-/overflow (result_out_of_range) also declines, so
 the caller's strtod fallback supplies the well-defined ±inf/0 result the parser
 expects (side-stepping the P4168 divergence between implementations).
 
@@ -9303,7 +9298,6 @@ class lexer : public lexer_base<BasicJsonType>
     explicit lexer(InputAdapterType&& adapter, bool ignore_comments_ = false, bool discard_number_values_ = false) noexcept
         : ia(std::move(adapter))
         , ignore_comments(ignore_comments_)
-        , decimal_point_char(static_cast<char_int_type>(get_decimal_point()))
         , discard_number_values(discard_number_values_)
     {}
 
@@ -9319,8 +9313,7 @@ class lexer : public lexer_base<BasicJsonType>
     // locales
     /////////////////////
 
-    /// return the locale-dependent decimal point
-    JSON_HEDLEY_PURE
+    /// return the decimal point of the current locale
     static char get_decimal_point() noexcept
     {
         const auto* loc = localeconv();
@@ -10189,9 +10182,10 @@ class lexer : public lexer_base<BasicJsonType>
             token_type::value_float if number could be successfully scanned,
             token_type::parse_error otherwise
 
-    @note The scanner is independent of the current locale. Internally, the
-          locale's decimal point is used instead of `.` to work with the
-          locale-dependent converters.
+    @note The scanner is independent of the current locale: token_buffer
+          always holds `.`. Only the std::strtod fallback of convert_number()
+          depends on the locale, and it looks up the decimal point right
+          before converting (see convert_float_locale_aware()).
     */
     token_type scan_number()  // lgtm [cpp/use-of-goto] `goto` is used in this function to implement the number-parsing state machine described above. By design, any finite input will eventually reach the "done" state or return token_type::parse_error. In each intermediate state, 1 byte of the input is appended to the token_buffer vector, and only the already initialized variables token_buffer, number_type, and error_message are manipulated.
     {
@@ -10280,7 +10274,7 @@ scan_number_zero:
         {
             case '.':
             {
-                add(decimal_point_char);
+                add(current);
                 decimal_point_position = token_buffer.size() - 1;
                 goto scan_number_decimal1;
             }
@@ -10317,7 +10311,7 @@ scan_number_any1:
 
             case '.':
             {
-                add(decimal_point_char);
+                add(current);
                 decimal_point_position = token_buffer.size() - 1;
                 goto scan_number_decimal1;
             }
@@ -10559,9 +10553,9 @@ scan_number_done:
 
         // Only a number below 1 can carry further insignificant zeros, and only
         // while the count stays at the limit does removing them change the
-        // answer - so this loop is skipped for all but a few tokens. Note
-        // token_buffer holds the locale's decimal point, so the fraction is
-        // located through decimal_point_position rather than by searching '.'.
+        // answer - so this loop is skipped for all but a few tokens. The
+        // fraction is located through decimal_point_position rather than by
+        // searching '.'.
         if (lead_zero != 0)
         {
             JSON_ASSERT(has_dot != 0); // an integer "0" cannot reach the limit
@@ -10579,8 +10573,8 @@ scan_number_done:
     @brief convert the number text in token_buffer to its value and token type
 
     The digit sequence in token_buffer has already been validated (by the
-    scan_number() state machine or by the contiguous fast path) and holds the
-    locale decimal point in place of '.'. Integers are parsed first and fall
+    scan_number() state machine or by the contiguous fast path) and holds '.'
+    as decimal point, independent of the locale. Integers are parsed first and fall
     back to floating point on overflow. This is shared so both scanners produce
     identical results.
 
@@ -10660,7 +10654,7 @@ scan_number_done:
         // integer conversion above overflowed. Prefer std::from_chars
         // (Eisel-Lemire, locale-independent, correctly rounded) when available;
         // otherwise the exact Clinger fast path (double only); otherwise the
-        // locale-aware strtof/strtod.
+        // locale-aware strtof/strtod/strtold.
         if (parse_float_from_chars(num_begin, num_end, value_float))
         {
             return token_type::value_float;
@@ -10669,26 +10663,75 @@ scan_number_done:
         // extra pass over the token's bytes, which otherwise shows up on
         // high-precision inputs such as canada.json
         if (mantissa_fits_clinger(mantissa_end)
-                && parse_float_fast(num_begin, num_end, decimal_point_char, value_float))
+                && parse_float_fast(num_begin, num_end, value_float))
         {
             return token_type::value_float;
         }
 
-        char* endptr = nullptr; // NOLINT(misc-const-correctness,cppcoreguidelines-pro-type-vararg,hicpp-vararg)
-        strtof(value_float, token_buffer.data(), &endptr);
-
-        // we checked the number format before
-        JSON_ASSERT(endptr == token_buffer.data() + token_buffer.size());
-
+        convert_float_locale_aware();
         return token_type::value_float;
     }
 
+    /*!
+    @brief convert the float in token_buffer with strtof/strtod/strtold
+
+    These functions expect the decimal point of the *current* locale, so it is
+    looked up right before the conversion instead of once when the lexer is
+    constructed: a locale change in between (by a parser callback, a SAX
+    handler, or another thread) must not truncate the value (#5198). The
+    token has been validated before, so if the conversion stops early and the
+    decimal point changed in the meantime, the locale changed between the
+    lookup and the call, and the conversion is repeated with the new decimal
+    point. If the decimal point did not change, a retry cannot succeed: the
+    locale's decimal point is not a single character (e.g., the two-byte
+    U+066B of ar_EG.UTF-8 or fa_IR.UTF-8) and cannot be substituted in place.
+    The value strtod parsed up to that point is kept, as before this change.
+
+    Note that changing the locale in another thread *while* strtod runs is
+    undefined behavior of the C library, which this function cannot prevent.
+    */
+    void convert_float_locale_aware()
+    {
+        const bool has_dot = decimal_point_position != std::string::npos;
+        char decimal_point = get_decimal_point();
+        for (;;)
+        {
+            const bool substitute = has_dot && decimal_point != '.';
+            if (substitute)
+            {
+                token_buffer[decimal_point_position] = static_cast<typename string_t::value_type>(decimal_point);
+            }
+
+            char* endptr = nullptr; // NOLINT(misc-const-correctness,cppcoreguidelines-pro-type-vararg,hicpp-vararg)
+            strtof(value_float, token_buffer.data(), &endptr);
+
+            if (substitute)
+            {
+                // get_string() hands the token to the SAX interface with '.'
+                token_buffer[decimal_point_position] = '.';
+            }
+
+            if (JSON_HEDLEY_LIKELY(endptr == token_buffer.data() + token_buffer.size()))
+            {
+                return;
+            }
+
+            // retry only if the locale changed; otherwise, this would loop forever
+            const char current_decimal_point = get_decimal_point();
+            if (current_decimal_point == decimal_point)
+            {
+                return;
+            }
+            decimal_point = current_decimal_point;
+        }
+    }
+
     /*!
     @brief contiguous fast path for scanning a number
 
     Parses the whole number token straight from the input buffer, avoiding the
     per-character get()/add() of scan_number(). On success it fills token_buffer
-    (with the locale decimal point substituted, as scan_number() does) and
+    (as scan_number() does) and
     returns the token type. On anything it does not fully recognize as a
     well-formed number it makes no state change and returns
     token_type::uninitialized, so the caller falls back to scan_number(), which
@@ -10804,16 +10847,11 @@ scan_number_done:
         }
 #endif
 
-        // materialize the token exactly as scan_number() would, substituting the
-        // locale decimal point so convert_number()'s strtof fallback stays valid.
-        // reset() already cleared token_buffer, so append() fills it (assign() is
-        // avoided because custom string_t types need not provide it)
+        // materialize the token exactly as scan_number() would. reset() already
+        // cleared token_buffer, so append() fills it (assign() is avoided
+        // because custom string_t types need not provide it)
         token_buffer.append(reinterpret_cast<const typename string_t::value_type*>(data), len);
-        if (dot_index != std::string::npos)
-        {
-            token_buffer[dot_index] = static_cast<typename string_t::value_type>(decimal_point_char);
-            decimal_point_position = dot_index;
-        }
+        decimal_point_position = dot_index;
 
         ia.bulk_skip(len - 1);
         position.chars_read_total += (len - 1);
@@ -11080,11 +11118,7 @@ scan_number_done:
     /// return current string value (implicitly resets the token; useful only once)
     string_t& get_string()
     {
-        // translate decimal points from locale back to '.' (#4084)
-        if (decimal_point_char != '.' && decimal_point_position != std::string::npos)
-        {
-            token_buffer[decimal_point_position] = '.';
-        }
+        // a number token holds '.' regardless of the locale (#4084)
         return token_buffer;
     }
 
@@ -11380,9 +11414,7 @@ scan_number_done:
     number_unsigned_t value_unsigned = 0;
     number_float_t value_float = 0;
 
-    /// the decimal point
-    const char_int_type decimal_point_char = '.';
-    /// the position of the decimal point in the input
+    /// the position of the decimal point in token_buffer
     std::size_t decimal_point_position = std::string::npos;
 
     /// whether the caller (e.g. accept()/json_sax_acceptor) only needs the
@@ -23931,8 +23963,7 @@ enum class error_handler_t
 {
     strict,  ///< throw a type_error exception in case of invalid UTF-8
     replace, ///< replace invalid UTF-8 sequences with U+FFFD
-    ignore,  ///< ignore invalid UTF-8 sequences
-    keep     ///< keep invalid UTF-8 sequences; their bytes are copied unchanged
+    ignore   ///< ignore invalid UTF-8 sequences
 };
 
 template<typename BasicJsonType>
@@ -24903,47 +24934,6 @@ class serializer
                             break;
                         }
 
-                        case error_handler_t::keep:
-                        {
-                            // drop whatever the incomplete sequence left in
-                            // the buffer (only copied if !EnsureAscii) and copy
-                            // the ill-formed bytes from the input instead
-                            bytes = bytes_after_last_accept;
-
-                            if (undumped_chars > 0)
-                            {
-                                // the pending bytes of the incomplete sequence
-                                // are ill-formed; the current byte may be OK for
-                                // itself, so we would like to read it again
-                                for (std::size_t j = i - undumped_chars; j < i; ++j)
-                                {
-                                    string_buffer[bytes++] = s[j];
-                                }
-                                --i;
-                            }
-                            else
-                            {
-                                // the current byte cannot start any sequence
-                                string_buffer[bytes++] = s[i];
-                            }
-
-                            // write buffer and reset index; there must be 13 bytes
-                            // left, as this is the maximal number of bytes to be
-                            // written ("\uxxxx\uxxxx\0") for one code point
-                            if (string_buffer.size() - bytes < 13)
-                            {
-                                put_buffer(string_buffer, bytes);
-                                bytes = 0;
-                            }
-
-                            bytes_after_last_accept = bytes;
-                            undumped_chars = 0;
-
-                            // continue processing the string
-                            state = UTF8_ACCEPT;
-                            break;
-                        }
-
                         default:            // LCOV_EXCL_LINE
                             JSON_ASSERT(false); // NOLINT(cert-dcl03-c,hicpp-static-assert,misc-static-assert) LCOV_EXCL_LINE
                     }
@@ -24989,15 +24979,6 @@ class serializer
                     break;
                 }
 
-                case error_handler_t::keep:
-                {
-                    // write all accepted bytes
-                    put_buffer(string_buffer, bytes_after_last_accept);
-                    // copy the bytes of the incomplete sequence unchanged
-                    put_string(s, s.size() - undumped_chars, s.size());
-                    break;
-                }
-
                 case error_handler_t::replace:
                 {
                     // write all accepted bytes

tests/src/unit-class_lexer.cpp

@@ -666,7 +666,7 @@ TEST_CASE("parse_float_fast declines what it cannot convert exactly")
     // always safe: the caller then falls back to a slower, exact conversion.
     const auto fast = [](const std::string & s, double & out)
     {
-        return nlohmann::detail::parse_float_fast(s.data(), s.data() + s.size(), '.', out);
+        return nlohmann::detail::parse_float_fast(s.data(), s.data() + s.size(), out);
     };
     double out = 0;
 

tests/src/unit-locale-cpp.cpp

@@ -12,7 +12,12 @@
 #include <nlohmann/json.hpp>
 using nlohmann::json;
 
+#include <array>
 #include <clocale>
+#include <map>
+#include <string>
+#include <utility>
+#include <vector>
 
 struct ParserImpl final: public nlohmann::json_sax<json>
 {
@@ -175,3 +180,208 @@ TEST_CASE("locale-dependent test (LC_NUMERIC=de_DE)")
         MESSAGE("locale de_DE is not usable");
     }
 }
+
+namespace
+{
+// records the numbers of a flat array and switches LC_NUMERIC to the given
+// locale once the array opens - after the lexer was constructed, but before
+// any number in the array is lexed
+struct LocaleSwitchingSax final: public nlohmann::json_sax<json>
+{
+    explicit LocaleSwitchingSax(const char* switch_to)
+        : locale_after_open(switch_to)
+    {}
+
+    bool null() override
+    {
+        return true;
+    }
+    bool boolean(bool /*val*/) override
+    {
+        return true;
+    }
+    bool number_integer(json::number_integer_t /*val*/) override
+    {
+        return true;
+    }
+    bool number_unsigned(json::number_unsigned_t /*val*/) override
+    {
+        return true;
+    }
+    bool number_float(json::number_float_t val, const json::string_t& s) override
+    {
+        values.push_back(val);
+        strings.push_back(s);
+        return true;
+    }
+    bool string(json::string_t& /*val*/) override
+    {
+        return true;
+    }
+    bool binary(json::binary_t& /*val*/) override
+    {
+        return true;
+    }
+    bool start_object(std::size_t /*val*/) override
+    {
+        return true;
+    }
+    bool key(json::string_t& /*val*/) override
+    {
+        return true;
+    }
+    bool end_object() override
+    {
+        return true;
+    }
+    bool start_array(std::size_t /*val*/) override
+    {
+        switched = std::setlocale(LC_NUMERIC, locale_after_open.c_str()) != nullptr;
+        return true;
+    }
+    bool end_array() override
+    {
+        return true;
+    }
+    bool parse_error(std::size_t /*val*/, const std::string& /*val*/, const nlohmann::detail::exception& /*val*/) override
+    {
+        return false;
+    }
+
+    std::string locale_after_open;
+    bool switched = false;
+    std::vector<json::number_float_t> values {}; // NOLINT(readability-redundant-member-init)
+    std::vector<json::string_t> strings {}; // NOLINT(readability-redundant-member-init)
+};
+} // namespace
+
+TEST_CASE("locale changes between lexer construction and number conversion (#5198)")
+{
+    // The numbers are chosen so that the conversion also takes the strtod
+    // fallback, which honors the locale that is current at conversion time:
+    // too many significant digits for Clinger's fast path, an underflow that
+    // std::from_chars rejects, and a plain value.
+    const std::vector<std::string> numbers = {"3.14159265358979323846", "1.5e-400", "12.34", "-0.000123456789012345678"};
+    std::string text = "[";
+    for (const auto& n : numbers)
+    {
+        text += (text.size() == 1 ? "" : ",") + n;
+    }
+    text += "]";
+
+    using long_double_json = nlohmann::basic_json<std::map, std::vector, std::string, bool, std::int64_t, std::uint64_t, long double>;
+
+    // reference values, parsed without a locale switch
+    REQUIRE(std::setlocale(LC_NUMERIC, "C") != nullptr);
+    const json expected = json::parse(text);
+    const long_double_json expected_ld = long_double_json::parse(text);
+
+    const std::array<std::pair<const char*, const char*>, 2> transitions =
+    {
+        {
+            {"C", "de_DE"},
+            {"de_DE", "C"}
+        }
+    };
+
+    for (const auto& transition : transitions)
+    {
+        CAPTURE(transition.first);
+        CAPTURE(transition.second);
+
+        if (std::setlocale(LC_NUMERIC, transition.first) == nullptr)
+        {
+            MESSAGE("locale is not usable");
+            continue;
+        }
+
+        // SAX parsing
+        {
+            LocaleSwitchingSax sax(transition.second);
+            CHECK(json::sax_parse(text, &sax));
+            if (sax.switched)
+            {
+                CHECK(sax.values == expected.get<std::vector<json::number_float_t>>());
+                CHECK(sax.strings == numbers);
+            }
+        }
+
+        // DOM parsing with a callback
+        {
+            bool switched = false;
+            const auto cb = [&](int /*depth*/, json::parse_event_t event, json& /*parsed*/)
+            {
+                if (event == json::parse_event_t::array_start)
+                {
+                    switched = std::setlocale(LC_NUMERIC, transition.second) != nullptr;
+                }
+                return true;
+            };
+            const json j = json::parse(text, cb);
+            if (switched)
+            {
+                CHECK(j == expected);
+            }
+        }
+
+        // a long double goes through std::strtold unless std::from_chars supports it
+        {
+            bool switched = false;
+            const auto cb = [&](int /*depth*/, long_double_json::parse_event_t event, long_double_json& /*parsed*/)
+            {
+                if (event == long_double_json::parse_event_t::array_start)
+                {
+                    switched = std::setlocale(LC_NUMERIC, transition.second) != nullptr;
+                }
+                return true;
+            };
+            const long_double_json j = long_double_json::parse(text, cb);
+            if (switched)
+            {
+                CHECK(j == expected_ld);
+            }
+        }
+    }
+
+    std::setlocale(LC_NUMERIC, "C");
+}
+
+TEST_CASE("locale with a multi-byte decimal point")
+{
+    // Some locales use a decimal point that is not a single character, e.g.
+    // U+066B ARABIC DECIMAL SEPARATOR (two bytes in UTF-8). It cannot be
+    // substituted in place for '.', so the strtod fallback stops early. The
+    // conversion must still terminate rather than retry forever.
+    const std::array<const char*, 6> names = {{"ar_EG.UTF-8", "ar_SA.UTF-8", "fa_IR.UTF-8", "ps_AF.UTF-8", "ar_EG", "fa_IR"}};
+    bool tested = false;
+    for (const char* name : names)
+    {
+        if (std::setlocale(LC_NUMERIC, name) == nullptr)
+        {
+            continue;
+        }
+        const std::string decimal_point = std::localeconv()->decimal_point;
+        if (decimal_point.size() < 2)
+        {
+            continue;
+        }
+        CAPTURE(name);
+        tested = true;
+
+        // too many significant digits for Clinger's fast path, and an underflow
+        // that std::from_chars rejects: both reach the strtod fallback
+        json j;
+        CHECK_NOTHROW(j = json::parse("[3.14159265358979323846, 1.5e-400, -0.000123456789012345678]"));
+        CHECK(j.is_array());
+        CHECK(json::accept("3.14159265358979323846"));
+
+        // a value the locale-independent paths convert is not affected
+        CHECK(json::parse("12.5") == 12.5);
+    }
+    if (!tested)
+    {
+        MESSAGE("no locale with a multi-byte decimal point is usable");
+    }
+
+    std::setlocale(LC_NUMERIC, "C");
+}

tests/src/unit-regression2.cpp

@@ -766,15 +766,6 @@ TEST_CASE("regression tests 2")
         CHECK(j == k);
     }
 
-    SECTION("issue #4552 - UTF-8 invalid characters are not always ignored when dumping with error_handler_t::ignore")
-    {
-        json node;
-        node["test"] = "test\334\005";
-        CHECK(node.dump(-1, ' ', false, json::error_handler_t::ignore) == "{\"test\":\"test\\u0005\"}");
-        CHECK(node.dump(-1, ' ', false, json::error_handler_t::keep) == "{\"test\":\"test\334\\u0005\"}");
-        CHECK(node.dump(-1, ' ', true, json::error_handler_t::keep) == "{\"test\":\"test\334\\u0005\"}");
-    }
-
 }
 
 TEST_CASE("regression test - parser callback must not lose a duplicate key's prior value")

tests/src/unit-serialization.cpp

@@ -92,8 +92,6 @@ TEST_CASE("serialization")
             CHECK(j.dump(-1, ' ', false, json::error_handler_t::ignore) == "\"äü\"");
             CHECK(j.dump(-1, ' ', false, json::error_handler_t::replace) == "\"ä\xEF\xBF\xBDü\"");
             CHECK(j.dump(-1, ' ', true, json::error_handler_t::replace) == "\"\\u00e4\\ufffd\\u00fc\"");
-            CHECK(j.dump(-1, ' ', false, json::error_handler_t::keep) == "\"ä\xA9ü\"");
-            CHECK(j.dump(-1, ' ', true, json::error_handler_t::keep) == "\"\\u00e4\xA9\\u00fc\"");
         }
 
         SECTION("invalid character (regression guard for shared UTF-8 decoder, see #5529)")
@@ -116,8 +114,6 @@ TEST_CASE("serialization")
             CHECK(j.dump(-1, ' ', false, json::error_handler_t::ignore) == "\"123\"");
             CHECK(j.dump(-1, ' ', false, json::error_handler_t::replace) == "\"123\xEF\xBF\xBD\"");
             CHECK(j.dump(-1, ' ', true, json::error_handler_t::replace) == "\"123\\ufffd\"");
-            CHECK(j.dump(-1, ' ', false, json::error_handler_t::keep) == "\"123\xC2\"");
-            CHECK(j.dump(-1, ' ', true, json::error_handler_t::keep) == "\"123\xC2\"");
         }
 
         SECTION("unexpected character")
@@ -130,39 +126,6 @@ TEST_CASE("serialization")
             CHECK(j.dump(-1, ' ', false, json::error_handler_t::ignore) == "\"123456\"");
             CHECK(j.dump(-1, ' ', false, json::error_handler_t::replace) == "\"123\xEF\xBF\xBD\x34\x35\x36\"");
             CHECK(j.dump(-1, ' ', true, json::error_handler_t::replace) == "\"123\\ufffd456\"");
-            CHECK(j.dump(-1, ' ', false, json::error_handler_t::keep) == "\"123\xF1\xB0\x34\x35\x36\"");
-            CHECK(j.dump(-1, ' ', true, json::error_handler_t::keep) == "\"123\xF1\xB0\x34\x35\x36\"");
-        }
-
-        SECTION("keep: valid characters are still escaped")
-        {
-            // an invalid byte followed by characters that must be escaped
-            const json j = "\xC2\"\\\n\xFF\x05";
-            CHECK(j.dump(-1, ' ', false, json::error_handler_t::keep) == "\"\xC2\\\"\\\\\\n\xFF\\u0005\"");
-            CHECK(j.dump(-1, ' ', true, json::error_handler_t::keep) == "\"\xC2\\\"\\\\\\n\xFF\\u0005\"");
-        }
-
-        SECTION("keep: truncated multibyte sequences")
-        {
-            CHECK(json("\xF0\x9F\x98").dump(-1, ' ', false, json::error_handler_t::keep) == "\"\xF0\x9F\x98\"");
-            CHECK(json("\xF0\x9F\x98").dump(-1, ' ', true, json::error_handler_t::keep) == "\"\xF0\x9F\x98\"");
-            CHECK(json("\xF0\x9F\x98" "a").dump(-1, ' ', false, json::error_handler_t::keep) == "\"\xF0\x9F\x98" "a\"");
-            CHECK(json("\xF0\x9F\x98" "a").dump(-1, ' ', true, json::error_handler_t::keep) == "\"\xF0\x9F\x98" "a\"");
-        }
-
-        SECTION("keep: long string with many invalid bytes")
-        {
-            // exceeds the internal string buffer several times
-            std::string input;
-            std::string expected = "\"";
-            for (int i = 0; i < 2000; ++i)
-            {
-                input += "\xFF\xE2\x82\n\xC3\xA4";
-                expected += "\xFF\xE2\x82\\n\xC3\xA4";
-            }
-            expected += "\"";
-            const json j = input;
-            CHECK(j.dump(-1, ' ', false, json::error_handler_t::keep) == expected);
         }
 
         SECTION("U+FFFD Substitution of Maximal Subparts")

tests/src/unit-unicode2.cpp

@@ -14,7 +14,6 @@
 #include <nlohmann/json.hpp>
 using nlohmann::json;
 
-#include <algorithm>
 #include <fstream>
 #include <sstream>
 #include <iostream>
@@ -76,11 +75,8 @@ void check_utf8dump(bool success_expected, int byte1, int byte2 = -1, int byte3
     static std::string s_replaced2;
     static std::string s_replaced_ascii;
     static std::string s_replaced2_ascii;
-    static std::string s_kept;
-    static std::string s_kept2;
-    static std::string s_kept_ascii;
 
-    // dumping with ignore/replace/keep must not throw in any case
+    // dumping with ignore/replace must not throw in any case
     s_ignored = j.dump(-1, ' ', false, json::error_handler_t::ignore);
     s_ignored2 = j2.dump(-1, ' ', false, json::error_handler_t::ignore);
     s_ignored_ascii = j.dump(-1, ' ', true, json::error_handler_t::ignore);
@@ -89,9 +85,6 @@ void check_utf8dump(bool success_expected, int byte1, int byte2 = -1, int byte3
     s_replaced2 = j2.dump(-1, ' ', false, json::error_handler_t::replace);
     s_replaced_ascii = j.dump(-1, ' ', true, json::error_handler_t::replace);
     s_replaced2_ascii = j2.dump(-1, ' ', true, json::error_handler_t::replace);
-    s_kept = j.dump(-1, ' ', false, json::error_handler_t::keep);
-    s_kept2 = j2.dump(-1, ' ', false, json::error_handler_t::keep);
-    s_kept_ascii = j.dump(-1, ' ', true, json::error_handler_t::keep);
 
     if (success_expected)
     {
@@ -101,7 +94,6 @@ void check_utf8dump(bool success_expected, int byte1, int byte2 = -1, int byte3
         // all dumps should agree on the string
         CHECK(s_strict == s_ignored);
         CHECK(s_strict == s_replaced);
-        CHECK(s_strict == s_kept);
     }
     else
     {
@@ -113,20 +105,6 @@ void check_utf8dump(bool success_expected, int byte1, int byte2 = -1, int byte3
 
         // check that replace string contains a replacement character
         CHECK(s_replaced.find("\xEF\xBF\xBD") != std::string::npos);
-
-        // ignore drops the invalid bytes, keep copies them
-        CHECK(s_ignored != s_kept);
-        CHECK(s_ignored_ascii != s_kept_ascii);
-
-        // unless a byte needs escaping, keep copies the input unchanged
-        const bool needs_escaping = std::any_of(json_string.begin(), json_string.end(), [](char c)
-        {
-            return static_cast<unsigned char>(c) < 0x20 || c == '"' || c == '\\';
-        });
-        if (!needs_escaping)
-        {
-            CHECK(s_kept == "\"" + json_string + "\"");
-        }
     }
 
     // check that prefix and suffix are preserved
@@ -138,8 +116,6 @@ void check_utf8dump(bool success_expected, int byte1, int byte2 = -1, int byte3
     CHECK(s_replaced2.substr(s_replaced2.size() - 4, 3) == "xyz");
     CHECK(s_replaced2_ascii.substr(1, 3) == "abc");
     CHECK(s_replaced2_ascii.substr(s_replaced2_ascii.size() - 4, 3) == "xyz");
-    CHECK(s_kept2.substr(1, 3) == "abc");
-    CHECK(s_kept2.substr(s_kept2.size() - 4, 3) == "xyz");
 }
 
 void check_utf8string(bool success_expected, int byte1, int byte2, int byte3, int byte4);

tests/src/unit-unicode3.cpp

@@ -14,7 +14,6 @@
 #include <nlohmann/json.hpp>
 using nlohmann::json;
 
-#include <algorithm>
 #include <fstream>
 #include <sstream>
 #include <iostream>
@@ -76,11 +75,8 @@ void check_utf8dump(bool success_expected, int byte1, int byte2 = -1, int byte3
     static std::string s_replaced2;
     static std::string s_replaced_ascii;
     static std::string s_replaced2_ascii;
-    static std::string s_kept;
-    static std::string s_kept2;
-    static std::string s_kept_ascii;
 
-    // dumping with ignore/replace/keep must not throw in any case
+    // dumping with ignore/replace must not throw in any case
     s_ignored = j.dump(-1, ' ', false, json::error_handler_t::ignore);
     s_ignored2 = j2.dump(-1, ' ', false, json::error_handler_t::ignore);
     s_ignored_ascii = j.dump(-1, ' ', true, json::error_handler_t::ignore);
@@ -89,9 +85,6 @@ void check_utf8dump(bool success_expected, int byte1, int byte2 = -1, int byte3
     s_replaced2 = j2.dump(-1, ' ', false, json::error_handler_t::replace);
     s_replaced_ascii = j.dump(-1, ' ', true, json::error_handler_t::replace);
     s_replaced2_ascii = j2.dump(-1, ' ', true, json::error_handler_t::replace);
-    s_kept = j.dump(-1, ' ', false, json::error_handler_t::keep);
-    s_kept2 = j2.dump(-1, ' ', false, json::error_handler_t::keep);
-    s_kept_ascii = j.dump(-1, ' ', true, json::error_handler_t::keep);
 
     if (success_expected)
     {
@@ -101,7 +94,6 @@ void check_utf8dump(bool success_expected, int byte1, int byte2 = -1, int byte3
         // all dumps should agree on the string
         CHECK(s_strict == s_ignored);
         CHECK(s_strict == s_replaced);
-        CHECK(s_strict == s_kept);
     }
     else
     {
@@ -113,20 +105,6 @@ void check_utf8dump(bool success_expected, int byte1, int byte2 = -1, int byte3
 
         // check that replace string contains a replacement character
         CHECK(s_replaced.find("\xEF\xBF\xBD") != std::string::npos);
-
-        // ignore drops the invalid bytes, keep copies them
-        CHECK(s_ignored != s_kept);
-        CHECK(s_ignored_ascii != s_kept_ascii);
-
-        // unless a byte needs escaping, keep copies the input unchanged
-        const bool needs_escaping = std::any_of(json_string.begin(), json_string.end(), [](char c)
-        {
-            return static_cast<unsigned char>(c) < 0x20 || c == '"' || c == '\\';
-        });
-        if (!needs_escaping)
-        {
-            CHECK(s_kept == "\"" + json_string + "\"");
-        }
     }
 
     // check that prefix and suffix are preserved
@@ -138,8 +116,6 @@ void check_utf8dump(bool success_expected, int byte1, int byte2 = -1, int byte3
     CHECK(s_replaced2.substr(s_replaced2.size() - 4, 3) == "xyz");
     CHECK(s_replaced2_ascii.substr(1, 3) == "abc");
     CHECK(s_replaced2_ascii.substr(s_replaced2_ascii.size() - 4, 3) == "xyz");
-    CHECK(s_kept2.substr(1, 3) == "abc");
-    CHECK(s_kept2.substr(s_kept2.size() - 4, 3) == "xyz");
 }
 
 void check_utf8string(bool success_expected, int byte1, int byte2, int byte3, int byte4);

tests/src/unit-unicode4.cpp

@@ -14,7 +14,6 @@
 #include <nlohmann/json.hpp>
 using nlohmann::json;
 
-#include <algorithm>
 #include <fstream>
 #include <sstream>
 #include <iostream>
@@ -76,11 +75,8 @@ void check_utf8dump(bool success_expected, int byte1, int byte2 = -1, int byte3
     static std::string s_replaced2;
     static std::string s_replaced_ascii;
     static std::string s_replaced2_ascii;
-    static std::string s_kept;
-    static std::string s_kept2;
-    static std::string s_kept_ascii;
 
-    // dumping with ignore/replace/keep must not throw in any case
+    // dumping with ignore/replace must not throw in any case
     s_ignored = j.dump(-1, ' ', false, json::error_handler_t::ignore);
     s_ignored2 = j2.dump(-1, ' ', false, json::error_handler_t::ignore);
     s_ignored_ascii = j.dump(-1, ' ', true, json::error_handler_t::ignore);
@@ -89,9 +85,6 @@ void check_utf8dump(bool success_expected, int byte1, int byte2 = -1, int byte3
     s_replaced2 = j2.dump(-1, ' ', false, json::error_handler_t::replace);
     s_replaced_ascii = j.dump(-1, ' ', true, json::error_handler_t::replace);
     s_replaced2_ascii = j2.dump(-1, ' ', true, json::error_handler_t::replace);
-    s_kept = j.dump(-1, ' ', false, json::error_handler_t::keep);
-    s_kept2 = j2.dump(-1, ' ', false, json::error_handler_t::keep);
-    s_kept_ascii = j.dump(-1, ' ', true, json::error_handler_t::keep);
 
     if (success_expected)
     {
@@ -101,7 +94,6 @@ void check_utf8dump(bool success_expected, int byte1, int byte2 = -1, int byte3
         // all dumps should agree on the string
         CHECK(s_strict == s_ignored);
         CHECK(s_strict == s_replaced);
-        CHECK(s_strict == s_kept);
     }
     else
     {
@@ -113,20 +105,6 @@ void check_utf8dump(bool success_expected, int byte1, int byte2 = -1, int byte3
 
         // check that replace string contains a replacement character
         CHECK(s_replaced.find("\xEF\xBF\xBD") != std::string::npos);
-
-        // ignore drops the invalid bytes, keep copies them
-        CHECK(s_ignored != s_kept);
-        CHECK(s_ignored_ascii != s_kept_ascii);
-
-        // unless a byte needs escaping, keep copies the input unchanged
-        const bool needs_escaping = std::any_of(json_string.begin(), json_string.end(), [](char c)
-        {
-            return static_cast<unsigned char>(c) < 0x20 || c == '"' || c == '\\';
-        });
-        if (!needs_escaping)
-        {
-            CHECK(s_kept == "\"" + json_string + "\"");
-        }
     }
 
     // check that prefix and suffix are preserved
@@ -138,8 +116,6 @@ void check_utf8dump(bool success_expected, int byte1, int byte2 = -1, int byte3
     CHECK(s_replaced2.substr(s_replaced2.size() - 4, 3) == "xyz");
     CHECK(s_replaced2_ascii.substr(1, 3) == "abc");
     CHECK(s_replaced2_ascii.substr(s_replaced2_ascii.size() - 4, 3) == "xyz");
-    CHECK(s_kept2.substr(1, 3) == "abc");
-    CHECK(s_kept2.substr(s_kept2.size() - 4, 3) == "xyz");
 }
 
 void check_utf8string(bool success_expected, int byte1, int byte2, int byte3, int byte4);

tests/src/unit-unicode5.cpp

@@ -14,7 +14,6 @@
 #include <nlohmann/json.hpp>
 using nlohmann::json;
 
-#include <algorithm>
 #include <fstream>
 #include <sstream>
 #include <iostream>
@@ -76,11 +75,8 @@ void check_utf8dump(bool success_expected, int byte1, int byte2 = -1, int byte3
     static std::string s_replaced2;
     static std::string s_replaced_ascii;
     static std::string s_replaced2_ascii;
-    static std::string s_kept;
-    static std::string s_kept2;
-    static std::string s_kept_ascii;
 
-    // dumping with ignore/replace/keep must not throw in any case
+    // dumping with ignore/replace must not throw in any case
     s_ignored = j.dump(-1, ' ', false, json::error_handler_t::ignore);
     s_ignored2 = j2.dump(-1, ' ', false, json::error_handler_t::ignore);
     s_ignored_ascii = j.dump(-1, ' ', true, json::error_handler_t::ignore);
@@ -89,9 +85,6 @@ void check_utf8dump(bool success_expected, int byte1, int byte2 = -1, int byte3
     s_replaced2 = j2.dump(-1, ' ', false, json::error_handler_t::replace);
     s_replaced_ascii = j.dump(-1, ' ', true, json::error_handler_t::replace);
     s_replaced2_ascii = j2.dump(-1, ' ', true, json::error_handler_t::replace);
-    s_kept = j.dump(-1, ' ', false, json::error_handler_t::keep);
-    s_kept2 = j2.dump(-1, ' ', false, json::error_handler_t::keep);
-    s_kept_ascii = j.dump(-1, ' ', true, json::error_handler_t::keep);
 
     if (success_expected)
     {
@@ -101,7 +94,6 @@ void check_utf8dump(bool success_expected, int byte1, int byte2 = -1, int byte3
         // all dumps should agree on the string
         CHECK(s_strict == s_ignored);
         CHECK(s_strict == s_replaced);
-        CHECK(s_strict == s_kept);
     }
     else
     {
@@ -113,20 +105,6 @@ void check_utf8dump(bool success_expected, int byte1, int byte2 = -1, int byte3
 
         // check that replace string contains a replacement character
         CHECK(s_replaced.find("\xEF\xBF\xBD") != std::string::npos);
-
-        // ignore drops the invalid bytes, keep copies them
-        CHECK(s_ignored != s_kept);
-        CHECK(s_ignored_ascii != s_kept_ascii);
-
-        // unless a byte needs escaping, keep copies the input unchanged
-        const bool needs_escaping = std::any_of(json_string.begin(), json_string.end(), [](char c)
-        {
-            return static_cast<unsigned char>(c) < 0x20 || c == '"' || c == '\\';
-        });
-        if (!needs_escaping)
-        {
-            CHECK(s_kept == "\"" + json_string + "\"");
-        }
     }
 
     // check that prefix and suffix are preserved
@@ -138,8 +116,6 @@ void check_utf8dump(bool success_expected, int byte1, int byte2 = -1, int byte3
     CHECK(s_replaced2.substr(s_replaced2.size() - 4, 3) == "xyz");
     CHECK(s_replaced2_ascii.substr(1, 3) == "abc");
     CHECK(s_replaced2_ascii.substr(s_replaced2_ascii.size() - 4, 3) == "xyz");
-    CHECK(s_kept2.substr(1, 3) == "abc");
-    CHECK(s_kept2.substr(s_kept2.size() - 4, 3) == "xyz");
 }
 
 void check_utf8string(bool success_expected, int byte1, int byte2, int byte3, int byte4);