Add JSON_DELETE_DEPRECATED_FUNCTIONS to delete the deprecated functions

Defining JSON_DELETE_DEPRECATED_FUNCTIONS to 1 (or the CMake option
JSON_DeleteDeprecatedFunctions) declares every deprecated function as
deleted instead of deprecated, so that code that is not ready for 4.0.0
no longer compiles. A deleted function still takes part in overload
resolution, so from_*(ptr, len) cannot silently bind len to the strict
parameter of from_*(InputType&&, bool); the roadmap now plans to keep
these overloads deleted in 4.0.0 instead of removing them.

The legacy discarded-value comparison is left to its own macro.

Also update the 4.0 roadmap: add JSON_DISABLE_TUPLE_REFERENCE_CONVERSION
and JSON_DELETE_DEPRECATED_FUNCTIONS to the macro table, add the
from_bjdata/from_bon8 (ptr, len) overloads to the deprecated functions,
document the macro in the migration guide, and fix the docs style check
findings (example titles, missing docset entry for JSON_STRICT_BINARY_UTF8).

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

tests/src/unit-bjdata.cpp

@@ -9,6 +9,14 @@
 #include "doctest_compatibility.h"
 
 #define JSON_TESTS_PRIVATE
+// capture whether JSON_DELETE_DEPRECATED_FUNCTIONS was enabled on the command
+// line *before* including json.hpp, since the library #undefs it once the header
+// has been fully processed (see include/nlohmann/detail/macro_unscope.hpp); the
+// tests of deprecated functions are skipped if these functions are deleted
+#if defined(JSON_DELETE_DEPRECATED_FUNCTIONS) && (JSON_DELETE_DEPRECATED_FUNCTIONS == 1)
+    #define JSON_TEST_DEPRECATED_FUNCTIONS_DELETED
+#endif
+
 #include <nlohmann/json.hpp>
 using nlohmann::json;
 
@@ -4505,6 +4513,7 @@ TEST_CASE("issue #5648 - from_bjdata(ptr, len) must read len bytes, not treat pt
     }
     REQUIRE(contains_nul);
 
+#ifndef JSON_TEST_DEPRECATED_FUNCTIONS_DELETED
     // before the fix, from_bjdata had no (ptr, len) overload, so this call
     // bound to from_bjdata(InputType&&, bool strict) instead: ptr was read
     // as a NUL-terminated C string (stopping at the embedded 0x00 byte), and
@@ -4517,4 +4526,5 @@ TEST_CASE("issue #5648 - from_bjdata(ptr, len) must read len bytes, not treat pt
 
     // len must not collapse into the strict flag either
     CHECK(json::from_bjdata(packed.data(), packed.size(), false) == j);
+#endif
 }

tests/src/unit-bon8.cpp

@@ -8,6 +8,14 @@
 
 #include "doctest_compatibility.h"
 
+// capture whether JSON_DELETE_DEPRECATED_FUNCTIONS was enabled on the command
+// line *before* including json.hpp, since the library #undefs it once the header
+// has been fully processed (see include/nlohmann/detail/macro_unscope.hpp); the
+// tests of deprecated functions are skipped if these functions are deleted
+#if defined(JSON_DELETE_DEPRECATED_FUNCTIONS) && (JSON_DELETE_DEPRECATED_FUNCTIONS == 1)
+    #define JSON_TEST_DEPRECATED_FUNCTIONS_DELETED
+#endif
+
 #include <nlohmann/json.hpp>
 using nlohmann::json;
 #ifdef JSON_TEST_NO_GLOBAL_UDLS
@@ -1026,6 +1034,7 @@ TEST_CASE("issue #5648 - from_bon8(ptr, len) must read len bytes, not treat ptr
     }
     REQUIRE(contains_nul);
 
+#ifndef JSON_TEST_DEPRECATED_FUNCTIONS_DELETED
     // before the fix, from_bon8 had no (ptr, len) overload, so this call
     // bound to from_bon8(InputType&&, bool strict) instead: ptr was read as
     // a NUL-terminated C string (stopping at the embedded 0x00 byte), and
@@ -1038,6 +1047,7 @@ TEST_CASE("issue #5648 - from_bon8(ptr, len) must read len bytes, not treat ptr
 
     // len must not collapse into the strict flag either
     CHECK(json::from_bon8(packed.data(), packed.size(), false) == j);
+#endif
 }
 
 #ifdef JSON_HAS_CPP_17

tests/src/unit-bson.cpp

@@ -8,6 +8,14 @@
 
 #include "doctest_compatibility.h"
 
+// capture whether JSON_DELETE_DEPRECATED_FUNCTIONS was enabled on the command
+// line *before* including json.hpp, since the library #undefs it once the header
+// has been fully processed (see include/nlohmann/detail/macro_unscope.hpp); the
+// tests of deprecated functions are skipped if these functions are deleted
+#if defined(JSON_DELETE_DEPRECATED_FUNCTIONS) && (JSON_DELETE_DEPRECATED_FUNCTIONS == 1)
+    #define JSON_TEST_DEPRECATED_FUNCTIONS_DELETED
+#endif
+
 #include <nlohmann/json.hpp>
 using nlohmann::json;
 
@@ -1259,8 +1267,10 @@ TEST_CASE("BSON input that cannot be read is discarded by every overload")
     CHECK_THROWS_AS(_ = json::from_bson(input.begin(), input.end()), json::parse_error&);
     CHECK(json::from_bson(input, true, false).is_discarded());
     CHECK(json::from_bson(input.begin(), input.end(), true, false).is_discarded());
+#ifndef JSON_TEST_DEPRECATED_FUNCTIONS_DELETED
     CHECK(json::from_bson(input.data(), input.size(), true, false).is_discarded());
     CHECK(json::from_bson({input.data(), input.size()}, true, false).is_discarded());
+#endif
 }
 
 TEST_CASE("BSON SAX parsing stops at every event")
@@ -1738,6 +1748,7 @@ TEST_CASE("BSON roundtrips" * doctest::skip())
                 CHECK(j1 == j2);
             }
 
+#ifndef JSON_TEST_DEPRECATED_FUNCTIONS_DELETED
             {
                 INFO_WITH_TEMP(filename + ": uint8_t* and size");
                 // parse JSON file
@@ -1752,6 +1763,7 @@ TEST_CASE("BSON roundtrips" * doctest::skip())
                 // compare parsed JSON values
                 CHECK(j1 == j2);
             }
+#endif
 
             {
                 INFO_WITH_TEMP(filename + ": output to output adapters");

tests/src/unit-cbor.cpp

@@ -8,6 +8,14 @@
 
 #include "doctest_compatibility.h"
 
+// capture whether JSON_DELETE_DEPRECATED_FUNCTIONS was enabled on the command
+// line *before* including json.hpp, since the library #undefs it once the header
+// has been fully processed (see include/nlohmann/detail/macro_unscope.hpp); the
+// tests of deprecated functions are skipped if these functions are deleted
+#if defined(JSON_DELETE_DEPRECATED_FUNCTIONS) && (JSON_DELETE_DEPRECATED_FUNCTIONS == 1)
+    #define JSON_TEST_DEPRECATED_FUNCTIONS_DELETED
+#endif
+
 #include <nlohmann/json.hpp>
 using nlohmann::json;
 
@@ -2215,8 +2223,10 @@ TEST_CASE("CBOR input that cannot be read is discarded by every overload")
     CHECK_THROWS_AS(_ = json::from_cbor(input.begin(), input.end()), json::parse_error&);
     CHECK(json::from_cbor(input, true, false).is_discarded());
     CHECK(json::from_cbor(input.begin(), input.end(), true, false).is_discarded());
+#ifndef JSON_TEST_DEPRECATED_FUNCTIONS_DELETED
     CHECK(json::from_cbor(input.data(), input.size(), true, false).is_discarded());
     CHECK(json::from_cbor({input.data(), input.size()}, true, false).is_discarded());
+#endif
 
     // a string that ends early, read through iterators that are not
     // contiguous and have to be copied from one element at a time
@@ -2611,12 +2621,14 @@ TEST_CASE("CBOR roundtrips" * doctest::skip())
                 CHECK(j1 == j2);
             }
 
+#ifndef JSON_TEST_DEPRECATED_FUNCTIONS_DELETED
             {
                 INFO_WITH_TEMP(filename + ": uint8_t* and size");
                 json j2;
                 CHECK_NOTHROW(j2 = json::from_cbor({packed.data(), packed.size()}));
                 CHECK(j1 == j2);
             }
+#endif
 
             {
                 INFO_WITH_TEMP(filename + ": output to output adapters");

tests/src/unit-delete_deprecated_functions.cpp

@@ -0,0 +1,214 @@
+//     __ _____ _____ _____
+//  __|  |   __|     |   | |  JSON for Modern C++ (supporting code)
+// |  |  |__   |  |  | | | |  version 3.12.0
+// |_____|_____|_____|_|___|  https://github.com/nlohmann/json
+//
+// SPDX-FileCopyrightText: 2013-2026 Niels Lohmann <https://nlohmann.me>
+// SPDX-License-Identifier: MIT
+
+#include "doctest_compatibility.h"
+
+// This file tests the opt-in JSON_DELETE_DEPRECATED_FUNCTIONS, so it defines the
+// macro itself instead of relying on the build configuration.
+#ifdef JSON_DELETE_DEPRECATED_FUNCTIONS
+    #undef JSON_DELETE_DEPRECATED_FUNCTIONS
+#endif
+#define JSON_DELETE_DEPRECATED_FUNCTIONS 1
+
+#include <nlohmann/json.hpp>
+using nlohmann::json;
+
+#include <cstddef>
+#include <cstdint>
+#include <istream>
+#include <ostream>
+#include <string>
+#include <type_traits>
+#include <utility>
+
+namespace
+{
+template<typename...>
+struct make_void
+{
+    using type = void;
+};
+
+template<typename... Ts>
+using void_t = typename make_void<Ts...>::type;
+
+// A deleted function is still found by overload resolution, but naming it in an
+// unevaluated operand is ill-formed, so each of the following traits is false
+// exactly if the expression selects a deleted (or no) function.
+#define JSON_TEST_DETECT(name, expr)                                 \
+    template<typename J, typename = void>                            \
+    struct name : std::false_type {};                                \
+    template<typename J>                                             \
+    struct name<J, void_t<decltype(expr)>> : std::true_type {}
+
+using ptr_t = const std::uint8_t*;
+
+JSON_TEST_DETECT(from_cbor_ptr_len, J::from_cbor(std::declval<ptr_t>(), std::declval<std::size_t>()));
+JSON_TEST_DETECT(from_msgpack_ptr_len, J::from_msgpack(std::declval<ptr_t>(), std::declval<std::size_t>()));
+JSON_TEST_DETECT(from_ubjson_ptr_len, J::from_ubjson(std::declval<ptr_t>(), std::declval<std::size_t>()));
+JSON_TEST_DETECT(from_bjdata_ptr_len, J::from_bjdata(std::declval<ptr_t>(), std::declval<std::size_t>()));
+JSON_TEST_DETECT(from_bon8_ptr_len, J::from_bon8(std::declval<ptr_t>(), std::declval<std::size_t>()));
+JSON_TEST_DETECT(from_bson_ptr_len, J::from_bson(std::declval<ptr_t>(), std::declval<std::size_t>()));
+
+JSON_TEST_DETECT(from_cbor_ptr_ptr, J::from_cbor(std::declval<ptr_t>(), std::declval<ptr_t>()));
+JSON_TEST_DETECT(from_msgpack_ptr_ptr, J::from_msgpack(std::declval<ptr_t>(), std::declval<ptr_t>()));
+JSON_TEST_DETECT(from_ubjson_ptr_ptr, J::from_ubjson(std::declval<ptr_t>(), std::declval<ptr_t>()));
+JSON_TEST_DETECT(from_bjdata_ptr_ptr, J::from_bjdata(std::declval<ptr_t>(), std::declval<ptr_t>()));
+JSON_TEST_DETECT(from_bon8_ptr_ptr, J::from_bon8(std::declval<ptr_t>(), std::declval<ptr_t>()));
+JSON_TEST_DETECT(from_bson_ptr_ptr, J::from_bson(std::declval<ptr_t>(), std::declval<ptr_t>()));
+
+JSON_TEST_DETECT(from_cbor_init_list, J::from_cbor({std::declval<ptr_t>(), std::declval<std::size_t>()}));
+JSON_TEST_DETECT(from_msgpack_init_list, J::from_msgpack({std::declval<ptr_t>(), std::declval<std::size_t>()}));
+JSON_TEST_DETECT(from_ubjson_init_list, J::from_ubjson({std::declval<ptr_t>(), std::declval<std::size_t>()}));
+JSON_TEST_DETECT(from_bson_init_list, J::from_bson({std::declval<ptr_t>(), std::declval<std::size_t>()}));
+
+JSON_TEST_DETECT(parse_init_list, J::parse({std::declval<ptr_t>(), std::declval<std::size_t>()}));
+JSON_TEST_DETECT(accept_init_list, J::accept({std::declval<ptr_t>(), std::declval<std::size_t>()}));
+JSON_TEST_DETECT(sax_parse_init_list, J::sax_parse({std::declval<ptr_t>(), std::declval<std::size_t>()}, std::declval<nlohmann::json_sax<J>*>()));
+JSON_TEST_DETECT(parse_ptr_ptr, J::parse(std::declval<ptr_t>(), std::declval<ptr_t>()));
+
+JSON_TEST_DETECT(iterator_wrapper, J::iterator_wrapper(std::declval<J&>()));
+JSON_TEST_DETECT(iterator_wrapper_const, J::iterator_wrapper(std::declval<const J&>()));
+JSON_TEST_DETECT(items, std::declval<J&>().items());
+
+JSON_TEST_DETECT(json_ltlt_istream, std::declval<J&>() << std::declval<std::istream&>());
+JSON_TEST_DETECT(istream_gtgt_json, std::declval<std::istream&>() >> std::declval<J&>());
+JSON_TEST_DETECT(json_gtgt_ostream, std::declval<const J&>() >> std::declval<std::ostream&>());
+JSON_TEST_DETECT(ostream_ltlt_json, std::declval<std::ostream&>() << std::declval<const J&>());
+
+JSON_TEST_DETECT(ptr_eq_ptr, std::declval<const typename J::json_pointer&>() == std::declval<const typename J::json_pointer&>());
+JSON_TEST_DETECT(ptr_ne_ptr, std::declval<const typename J::json_pointer&>() != std::declval<const typename J::json_pointer&>());
+JSON_TEST_DETECT(ptr_eq_string, std::declval<const typename J::json_pointer&>() == std::declval<const std::string&>());
+JSON_TEST_DETECT(string_eq_ptr, std::declval<const std::string&>() == std::declval<const typename J::json_pointer&>());
+JSON_TEST_DETECT(ptr_eq_c_string, std::declval<const typename J::json_pointer&>() == std::declval<const char*>());
+JSON_TEST_DETECT(c_string_eq_ptr, std::declval<const char*>() == std::declval<const typename J::json_pointer&>());
+JSON_TEST_DETECT(ptr_ne_string, std::declval<const typename J::json_pointer&>() != std::declval<const std::string&>());
+JSON_TEST_DETECT(string_ne_ptr, std::declval<const std::string&>() != std::declval<const typename J::json_pointer&>());
+JSON_TEST_DETECT(ptr_to_string, std::declval<const typename J::json_pointer&>().to_string());
+
+// json_pointer with a basic_json type as template argument
+template<typename J>
+using legacy_ptr_t = const nlohmann::json_pointer<J>& ;
+JSON_TEST_DETECT(legacy_ptr_value, std::declval<const J&>().value(std::declval<legacy_ptr_t<J>>(), 0));
+JSON_TEST_DETECT(legacy_ptr_value_rvalue, std::declval<const J&>().value(std::declval<legacy_ptr_t<J>>(), std::string()));
+JSON_TEST_DETECT(legacy_ptr_contains, std::declval<const J&>().contains(std::declval<legacy_ptr_t<J>>()));
+JSON_TEST_DETECT(legacy_ptr_subscript, std::declval<J&>()[std::declval<legacy_ptr_t<J>>()]);
+JSON_TEST_DETECT(legacy_ptr_subscript_const, std::declval<const J&>()[std::declval<legacy_ptr_t<J>>()]);
+JSON_TEST_DETECT(legacy_ptr_at, std::declval<J&>().at(std::declval<legacy_ptr_t<J>>()));
+JSON_TEST_DETECT(legacy_ptr_at_const, std::declval<const J&>().at(std::declval<legacy_ptr_t<J>>()));
+JSON_TEST_DETECT(ptr_value, std::declval<const J&>().value(std::declval<const typename J::json_pointer&>(), 0));
+JSON_TEST_DETECT(ptr_at, std::declval<J&>().at(std::declval<const typename J::json_pointer&>()));
+
+#undef JSON_TEST_DETECT
+} // namespace
+
+TEST_CASE("JSON_DELETE_DEPRECATED_FUNCTIONS")
+{
+    SECTION("from_* with a pointer and a length")
+    {
+        // the overloads are deleted rather than removed, so the length cannot
+        // silently bind to the strict parameter of from_*(InputType&&, bool)
+        CHECK_FALSE(from_cbor_ptr_len<json>::value);
+        CHECK_FALSE(from_msgpack_ptr_len<json>::value);
+        CHECK_FALSE(from_ubjson_ptr_len<json>::value);
+        CHECK_FALSE(from_bjdata_ptr_len<json>::value);
+        CHECK_FALSE(from_bon8_ptr_len<json>::value);
+        CHECK_FALSE(from_bson_ptr_len<json>::value);
+
+        // the replacement
+        CHECK(from_cbor_ptr_ptr<json>::value);
+        CHECK(from_msgpack_ptr_ptr<json>::value);
+        CHECK(from_ubjson_ptr_ptr<json>::value);
+        CHECK(from_bjdata_ptr_ptr<json>::value);
+        CHECK(from_bon8_ptr_ptr<json>::value);
+        CHECK(from_bson_ptr_ptr<json>::value);
+    }
+
+    SECTION("initializer lists of a pointer and a length")
+    {
+        CHECK_FALSE(from_cbor_init_list<json>::value);
+        CHECK_FALSE(from_msgpack_init_list<json>::value);
+        CHECK_FALSE(from_ubjson_init_list<json>::value);
+        CHECK_FALSE(from_bson_init_list<json>::value);
+        CHECK_FALSE(parse_init_list<json>::value);
+        CHECK_FALSE(accept_init_list<json>::value);
+        CHECK_FALSE(sax_parse_init_list<json>::value);
+
+        // the replacement
+        CHECK(parse_ptr_ptr<json>::value);
+    }
+
+    SECTION("iterator_wrapper")
+    {
+        CHECK_FALSE(iterator_wrapper<json>::value);
+        CHECK_FALSE(iterator_wrapper_const<json>::value);
+
+        // the replacement
+        CHECK(items<json>::value);
+    }
+
+    SECTION("stream operators with reversed operands")
+    {
+        CHECK_FALSE(json_ltlt_istream<json>::value);
+        CHECK_FALSE(json_gtgt_ostream<json>::value);
+
+        // the replacement
+        CHECK(istream_gtgt_json<json>::value);
+        CHECK(ostream_ltlt_json<json>::value);
+    }
+
+    SECTION("json_pointer")
+    {
+        // conversion to a string
+        CHECK_FALSE(std::is_constructible<std::string, json::json_pointer>::value);
+        CHECK_FALSE(std::is_convertible<json::json_pointer, std::string>::value);
+
+        // comparison with a string
+        CHECK_FALSE(ptr_eq_string<json>::value);
+        CHECK_FALSE(string_eq_ptr<json>::value);
+        CHECK_FALSE(ptr_eq_c_string<json>::value);
+        CHECK_FALSE(c_string_eq_ptr<json>::value);
+        CHECK_FALSE(ptr_ne_string<json>::value);
+        CHECK_FALSE(string_ne_ptr<json>::value);
+
+        // the replacement
+        CHECK(ptr_to_string<json>::value);
+        CHECK(ptr_eq_ptr<json>::value);
+        CHECK(ptr_ne_ptr<json>::value);
+    }
+
+    SECTION("json_pointer with a basic_json type as template argument")
+    {
+        CHECK_FALSE(legacy_ptr_value<json>::value);
+        CHECK_FALSE(legacy_ptr_value_rvalue<json>::value);
+        CHECK_FALSE(legacy_ptr_contains<json>::value);
+        CHECK_FALSE(legacy_ptr_subscript<json>::value);
+        CHECK_FALSE(legacy_ptr_subscript_const<json>::value);
+        CHECK_FALSE(legacy_ptr_at<json>::value);
+        CHECK_FALSE(legacy_ptr_at_const<json>::value);
+
+        // the replacement
+        CHECK(ptr_value<json>::value);
+        CHECK(ptr_at<json>::value);
+    }
+
+    SECTION("the non-deprecated functions still work")
+    {
+        const json j = {{"a", {1, 2}}};
+        const auto cbor = json::to_cbor(j);
+        CHECK(json::from_cbor(cbor.data(), cbor.data() + cbor.size()) == j);
+
+        const json::json_pointer ptr("/a/1");
+        CHECK(ptr == json::json_pointer("/a/1"));
+        CHECK(ptr.to_string() == "/a/1");
+        CHECK(j[ptr] == 2);
+        CHECK(j.at(ptr) == 2);
+        CHECK(j.value(ptr, 0) == 2);
+        CHECK(j.contains(ptr));
+    }
+}

tests/src/unit-deserialization.cpp

@@ -16,6 +16,14 @@
     #define JSON_TEST_STRICT_NUL_HANDLING_ENABLED 1
 #endif
 
+// capture whether JSON_DELETE_DEPRECATED_FUNCTIONS was enabled on the command
+// line *before* including json.hpp, since the library #undefs it once the header
+// has been fully processed (see include/nlohmann/detail/macro_unscope.hpp); the
+// tests of deprecated functions are skipped if these functions are deleted
+#if defined(JSON_DELETE_DEPRECATED_FUNCTIONS) && (JSON_DELETE_DEPRECATED_FUNCTIONS == 1)
+    #define JSON_TEST_DEPRECATED_FUNCTIONS_DELETED
+#endif
+
 #include <nlohmann/json.hpp>
 using nlohmann::json;
 #ifdef JSON_TEST_NO_GLOBAL_UDLS
@@ -291,6 +299,7 @@ TEST_CASE("deserialization")
             }));
         }
 
+#ifndef JSON_TEST_DEPRECATED_FUNCTIONS_DELETED
         SECTION("operator<<")
         {
             std::stringstream ss;
@@ -299,6 +308,7 @@ TEST_CASE("deserialization")
             j << ss;
             CHECK(j == json({"foo", 1, 2, 3, false, {{"one", 1}}}));
         }
+#endif
 
         SECTION("operator>>")
         {
@@ -423,6 +433,7 @@ TEST_CASE("deserialization")
             CHECK_THROWS_WITH_AS(_ = json::parse(nullptr), "[json.exception.parse_error.101] parse error: attempting to parse an empty input; check that your input string or stream contains the expected JSON", json::parse_error&);
         }
 
+#ifndef JSON_TEST_DEPRECATED_FUNCTIONS_DELETED
         SECTION("operator<<")
         {
             std::stringstream ss;
@@ -430,6 +441,7 @@ TEST_CASE("deserialization")
             json j;
             CHECK_THROWS_WITH_AS(j << ss, "[json.exception.parse_error.101] parse error at line 1, column 29: syntax error while parsing array - unexpected end of input; expected ']'", json::parse_error&);
         }
+#endif
 
         SECTION("operator>>")
         {
@@ -1148,9 +1160,9 @@ TEST_CASE("deserialization")
         {
             std::istringstream s(bom + "123 456");
             json j;
-            j << s;
+            s >> j;
             CHECK(j == 123);
-            j << s;
+            s >> j;
             CHECK(j == 456);
         }
     }

tests/src/unit-items.cpp

@@ -8,6 +8,14 @@
 
 #include "doctest_compatibility.h"
 
+// capture whether JSON_DELETE_DEPRECATED_FUNCTIONS was enabled on the command
+// line *before* including json.hpp, since the library #undefs it once the header
+// has been fully processed (see include/nlohmann/detail/macro_unscope.hpp); the
+// tests of deprecated functions are skipped if these functions are deleted
+#if defined(JSON_DELETE_DEPRECATED_FUNCTIONS) && (JSON_DELETE_DEPRECATED_FUNCTIONS == 1)
+    #define JSON_TEST_DEPRECATED_FUNCTIONS_DELETED
+#endif
+
 #include <nlohmann/json.hpp>
 using nlohmann::json;
 
@@ -19,6 +27,7 @@ DOCTEST_GCC_SUPPRESS_WARNING_PUSH
 DOCTEST_CLANG_SUPPRESS_WARNING_PUSH
 DOCTEST_CLANG_SUPPRESS_WARNING("-Wrange-loop-construct")
 
+#ifndef JSON_TEST_DEPRECATED_FUNCTIONS_DELETED
 TEST_CASE("iterator_wrapper")
 {
     SECTION("object")
@@ -715,6 +724,7 @@ TEST_CASE("iterator_wrapper")
         }
     }
 }
+#endif
 
 TEST_CASE("items()")
 {

tests/src/unit-json_pointer.cpp

@@ -9,6 +9,14 @@
 #include "doctest_compatibility.h"
 
 #define JSON_TESTS_PRIVATE
+// capture whether JSON_DELETE_DEPRECATED_FUNCTIONS was enabled on the command
+// line *before* including json.hpp, since the library #undefs it once the header
+// has been fully processed (see include/nlohmann/detail/macro_unscope.hpp); the
+// tests of deprecated functions are skipped if these functions are deleted
+#if defined(JSON_DELETE_DEPRECATED_FUNCTIONS) && (JSON_DELETE_DEPRECATED_FUNCTIONS == 1)
+    #define JSON_TEST_DEPRECATED_FUNCTIONS_DELETED
+#endif
+
 #include <nlohmann/json.hpp>
 using nlohmann::json;
 #ifdef JSON_TEST_NO_GLOBAL_UDLS
@@ -564,7 +572,9 @@ TEST_CASE("JSON pointers")
             std::stringstream ss;
             ss << ptr;
             CHECK(ptr.to_string() == ptr_str);
+#ifndef JSON_TEST_DEPRECATED_FUNCTIONS_DELETED
             CHECK(std::string(ptr) == ptr_str);
+#endif
             CHECK(ss.str() == ptr_str);
         }
     }
@@ -744,8 +754,6 @@ TEST_CASE("JSON pointers")
 
     SECTION("equality comparison")
     {
-        const char* ptr_cpstring = "/foo/bar";
-        const char ptr_castring[] = "/foo/bar"; // NOLINT(misc-const-correctness,hicpp-avoid-c-arrays,modernize-avoid-c-arrays,cppcoreguidelines-avoid-c-arrays)
         std::string ptr_string{"/foo/bar"};
         auto ptr1 = json::json_pointer(ptr_string);
         auto ptr2 = json::json_pointer(ptr_string);
@@ -755,6 +763,12 @@ TEST_CASE("JSON pointers")
 
         CHECK(ptr1 == ptr2);
 
+        CHECK_FALSE(ptr1 != ptr2);
+
+#ifndef JSON_TEST_DEPRECATED_FUNCTIONS_DELETED
+        const char* ptr_cpstring = "/foo/bar";
+        const char ptr_castring[] = "/foo/bar"; // NOLINT(misc-const-correctness,hicpp-avoid-c-arrays,modernize-avoid-c-arrays,cppcoreguidelines-avoid-c-arrays)
+
         CHECK(ptr1 == "/foo/bar");
         CHECK(ptr1 == ptr_cpstring);
         CHECK(ptr1 == ptr_castring);
@@ -765,8 +779,6 @@ TEST_CASE("JSON pointers")
         CHECK(ptr_castring == ptr1);
         CHECK(ptr_string == ptr1);
 
-        CHECK_FALSE(ptr1 != ptr2);
-
         CHECK_FALSE(ptr1 != "/foo/bar");
         CHECK_FALSE(ptr1 != ptr_cpstring);
         CHECK_FALSE(ptr1 != ptr_castring);
@@ -788,6 +800,7 @@ TEST_CASE("JSON pointers")
             CHECK_THROWS_WITH_AS("/~~" == ptr1,
                                  "[json.exception.parse_error.108] parse error: escape character '~' must be followed with '0' or '1'", json::parse_error&);
         }
+#endif
     }
 
     SECTION("less-than comparison")
@@ -839,6 +852,7 @@ TEST_CASE("JSON pointers")
         json_ptr_j ptr_j{ptr_string};
         json_ptr_oj ptr_oj{ptr_string};
 
+#ifndef JSON_TEST_DEPRECATED_FUNCTIONS_DELETED
         CHECK(j.contains(ptr));
         CHECK(j.contains(ptr_j));
         CHECK(j.contains(ptr_oj));
@@ -851,6 +865,7 @@ TEST_CASE("JSON pointers")
 
         CHECK(j.value(ptr, "x") == j.value(ptr_j, "x"));
         CHECK(j.value(ptr, "x") == j.value(ptr_oj, "x"));
+#endif
 
         CHECK(ptr == ptr_j);
         CHECK(ptr == ptr_oj);

tests/src/unit-msgpack.cpp

@@ -8,6 +8,14 @@
 
 #include "doctest_compatibility.h"
 
+// capture whether JSON_DELETE_DEPRECATED_FUNCTIONS was enabled on the command
+// line *before* including json.hpp, since the library #undefs it once the header
+// has been fully processed (see include/nlohmann/detail/macro_unscope.hpp); the
+// tests of deprecated functions are skipped if these functions are deleted
+#if defined(JSON_DELETE_DEPRECATED_FUNCTIONS) && (JSON_DELETE_DEPRECATED_FUNCTIONS == 1)
+    #define JSON_TEST_DEPRECATED_FUNCTIONS_DELETED
+#endif
+
 #include <nlohmann/json.hpp>
 using nlohmann::json;
 #ifdef JSON_TEST_NO_GLOBAL_UDLS
@@ -1795,8 +1803,10 @@ TEST_CASE("MessagePack input that cannot be read is discarded by every overload"
     CHECK_THROWS_AS(_ = json::from_msgpack(input.begin(), input.end()), json::parse_error&);
     CHECK(json::from_msgpack(input, true, false).is_discarded());
     CHECK(json::from_msgpack(input.begin(), input.end(), true, false).is_discarded());
+#ifndef JSON_TEST_DEPRECATED_FUNCTIONS_DELETED
     CHECK(json::from_msgpack(input.data(), input.size(), true, false).is_discarded());
     CHECK(json::from_msgpack({input.data(), input.size()}, true, false).is_discarded());
+#endif
 }
 
 TEST_CASE("MessagePack SAX parsing stops at every event")
@@ -2099,12 +2109,14 @@ TEST_CASE("MessagePack roundtrips" * doctest::skip())
                 CHECK(j1 == j2);
             }
 
+#ifndef JSON_TEST_DEPRECATED_FUNCTIONS_DELETED
             {
                 INFO_WITH_TEMP(filename + ": uint8_t* and size");
                 json j2;
                 CHECK_NOTHROW(j2 = json::from_msgpack({packed.data(), packed.size()}));
                 CHECK(j1 == j2);
             }
+#endif
 
             {
                 INFO_WITH_TEMP(filename + ": output to output adapters");

tests/src/unit-regression2.cpp

@@ -569,7 +569,7 @@ TEST_CASE("regression tests 2")
     SECTION("issue #2067 - cannot serialize binary data to text JSON")
     {
         const std::array<unsigned char, 23> data = {{0x81, 0xA4, 0x64, 0x61, 0x74, 0x61, 0xC4, 0x0F, 0x33, 0x30, 0x30, 0x32, 0x33, 0x34, 0x30, 0x31, 0x30, 0x37, 0x30, 0x35, 0x30, 0x31, 0x30}};
-        const json j = json::from_msgpack(data.data(), data.size());
+        const json j = json::from_msgpack(data.begin(), data.end());
         // dump() is nodiscard; this only checks that dumping does not throw
         CHECK_NOTHROW(
             utils::ignore_return_value(

tests/src/unit-serialization.cpp

@@ -8,6 +8,14 @@
 
 #include "doctest_compatibility.h"
 
+// capture whether JSON_DELETE_DEPRECATED_FUNCTIONS was enabled on the command
+// line *before* including json.hpp, since the library #undefs it once the header
+// has been fully processed (see include/nlohmann/detail/macro_unscope.hpp); the
+// tests of deprecated functions are skipped if these functions are deleted
+#if defined(JSON_DELETE_DEPRECATED_FUNCTIONS) && (JSON_DELETE_DEPRECATED_FUNCTIONS == 1)
+    #define JSON_TEST_DEPRECATED_FUNCTIONS_DELETED
+#endif
+
 #include <nlohmann/json.hpp>
 using nlohmann::json;
 
@@ -48,6 +56,7 @@ TEST_CASE("serialization")
         }
     }
 
+#ifndef JSON_TEST_DEPRECATED_FUNCTIONS_DELETED
     SECTION("operator>>")
     {
         SECTION("no given width")
@@ -79,6 +88,7 @@ TEST_CASE("serialization")
                   "[\n\t\"foo\",\n\t1,\n\t2,\n\t3,\n\tfalse,\n\t{\n\t\t\"one\": 1\n\t}\n]");
         }
     }
+#endif
 
     SECTION("dump")
     {

tests/src/unit-ubjson.cpp

@@ -8,6 +8,14 @@
 
 #include "doctest_compatibility.h"
 
+// capture whether JSON_DELETE_DEPRECATED_FUNCTIONS was enabled on the command
+// line *before* including json.hpp, since the library #undefs it once the header
+// has been fully processed (see include/nlohmann/detail/macro_unscope.hpp); the
+// tests of deprecated functions are skipped if these functions are deleted
+#if defined(JSON_DELETE_DEPRECATED_FUNCTIONS) && (JSON_DELETE_DEPRECATED_FUNCTIONS == 1)
+    #define JSON_TEST_DEPRECATED_FUNCTIONS_DELETED
+#endif
+
 #include <nlohmann/json.hpp>
 using nlohmann::json;
 
@@ -2212,8 +2220,10 @@ TEST_CASE("UBJSON input that cannot be read is discarded by every overload")
     CHECK_THROWS_AS(_ = json::from_ubjson(input.begin(), input.end()), json::parse_error&);
     CHECK(json::from_ubjson(input, true, false).is_discarded());
     CHECK(json::from_ubjson(input.begin(), input.end(), true, false).is_discarded());
+#ifndef JSON_TEST_DEPRECATED_FUNCTIONS_DELETED
     CHECK(json::from_ubjson(input.data(), input.size(), true, false).is_discarded());
     CHECK(json::from_ubjson({input.data(), input.size()}, true, false).is_discarded());
+#endif
 }
 
 TEST_CASE("UBJSON SAX parsing stops at every event")
@@ -2961,12 +2971,14 @@ TEST_CASE("UBJSON roundtrips" * doctest::skip())
                 CHECK(j1 == j2);
             }
 
+#ifndef JSON_TEST_DEPRECATED_FUNCTIONS_DELETED
             {
                 INFO_WITH_TEMP(filename + ": uint8_t* and size");
                 json j2;
                 CHECK_NOTHROW(j2 = json::from_ubjson({packed.data(), packed.size()}));
                 CHECK(j1 == j2);
             }
+#endif
 
             {
                 INFO_WITH_TEMP(filename + ": output to output adapters");