Reject integer lengths in json_document::parse

parse(ptr, len) compiled: len converted to allow_exceptions, and ptr was
read as a C string, past the end of a buffer without a terminating NUL.
Delete the overloads of parse, parse_copy, accept, and read that take an
integer other than bool where the flags are expected.

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

include/nlohmann/detail/view/input.hpp

@@ -59,6 +59,13 @@ struct classify_input
     // NOLINTEND(readability-avoid-nested-conditional-operator)
 };
 
+/// an integer type other than bool: a length passed where a flag is expected
+template<typename T>
+struct is_integer_not_bool : std::is_integral<T> {};
+
+template<>
+struct is_integer_not_bool<bool> : std::false_type {};
+
 /// std::basic_string guarantees a NUL at data()[size()] (the parser's sentinel)
 template<typename T>
 struct is_std_string : std::false_type {};

include/nlohmann/json_view.hpp

@@ -291,6 +291,13 @@ class basic_json_document
         return d;
     }
 
+    /// parse(ptr, len) does not compile: len would convert to allow_exceptions
+    /// and ptr be read as a C string (as for the overloads of parse_copy,
+    /// accept, and read below)
+    template<typename InputType, typename IntegerType, typename... Flags>
+    static typename std::enable_if<detail::view::is_integer_not_bool<IntegerType>::value, basic_json_document>::type
+    parse(InputType&& input, IntegerType value, Flags&&... flags) = delete;
+
     /// parse [first, last)
     template<typename IteratorType, typename std::enable_if<
                  std::is_base_of<std::input_iterator_tag, typename std::iterator_traits<IteratorType>::iterator_category>::value, int>::type = 0>
@@ -318,6 +325,10 @@ class basic_json_document
         return d;
     }
 
+    template<typename InputType, typename IntegerType, typename... Flags>
+    static typename std::enable_if<detail::view::is_integer_not_bool<IntegerType>::value, basic_json_document>::type
+    parse_copy(InputType&& input, IntegerType value, Flags&&... flags) = delete;
+
     /// check whether the input is valid JSON (the result of basic_json::accept)
     template<typename InputType>
     static bool accept(InputType&& input, const bool ignore_comments = false, const bool ignore_trailing_commas = false)
@@ -327,6 +338,10 @@ class basic_json_document
         return !d.is_discarded();
     }
 
+    template<typename InputType, typename IntegerType, typename... Flags>
+    static typename std::enable_if<detail::view::is_integer_not_bool<IntegerType>::value, bool>::type
+    accept(InputType&& input, IntegerType value, Flags&&... flags) = delete;
+
     /// parse into this document, reusing its memory
     template<typename InputType>
     // flawfinder: ignore (a member function, not POSIX read())
@@ -339,6 +354,11 @@ class basic_json_document
                   std::integral_constant<detail::view::input_kind, detail::view::classify_input<InputType>::value> {});
     }
 
+    template<typename InputType, typename IntegerType, typename... Flags>
+    // flawfinder: ignore (a member function, not POSIX read())
+    typename std::enable_if<detail::view::is_integer_not_bool<IntegerType>::value, void>::type
+    read(InputType&& input, IntegerType value, Flags&&... flags) = delete;
+
     ////////////
     // access //
     ////////////