Account for JSON_DIAGNOSTIC_POSITIONS in the move-prefix-check error messages

out_of_range::create() includes a "(bytes X-Y)" position annotation when
JSON_DIAGNOSTIC_POSITIONS is enabled, which the ci_test_diagnostic_positions
CI job builds the whole suite with. The five new out_of_range.414
assertions only checked the annotation-free message. Confirmed
JSON_DIAGNOSTICS produces the same (annotation-free) message as the
default build for this particular throw site (its path-based annotation
is empty at the root, where &result always points here), so only two
message variants are needed, not three.

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

docs/mkdocs/docs/api/basic_json/patch.md

@@ -34,6 +34,10 @@ Strong guarantee: if an exception is thrown, there are no changes in the JSON va
   ("add", "remove", "move")
 - Throws [`out_of_range.411`](../../home/exceptions.md#jsonexceptionout_of_range411) if an "add" operation's target
   location has a parent that is neither an object nor an array.
+- Throws [`out_of_range.413`](../../home/exceptions.md#jsonexceptionout_of_range413) if a "remove" operation's target
+  location has a parent that is neither an object nor an array.
+- Throws [`out_of_range.414`](../../home/exceptions.md#jsonexceptionout_of_range414) if a "move" operation's "from"
+  location is a proper prefix of its "path" location.
 - Throws [`other_error.501`](../../home/exceptions.md#jsonexceptionother_error501) if "test" operation was
   unsuccessful.
 
@@ -75,3 +79,7 @@ is thrown. In any case, the original value is not changed: the patch is applied
 - Added in version 2.0.0.
 - Added [`out_of_range.411`](../../home/exceptions.md#jsonexceptionout_of_range411) and stopped relying on an internal assertion when an "add" operation's
   target location has a non-object/non-array parent in version 3.13.0.
+- Added [`out_of_range.413`](../../home/exceptions.md#jsonexceptionout_of_range413) and stopped silently ignoring a "remove" operation whose target
+  location has a non-object/non-array parent in version 3.13.0.
+- Added [`out_of_range.414`](../../home/exceptions.md#jsonexceptionout_of_range414) and rejected a "move" operation whose "from" location is a proper
+  prefix of its "path" location instead of silently producing a corrupted result in version 3.13.0.

docs/mkdocs/docs/api/basic_json/patch_inplace.md

@@ -30,6 +30,10 @@ No guarantees, value may be corrupted by an unsuccessful patch operation.
   ("add", "remove", "move")
 - Throws [`out_of_range.411`](../../home/exceptions.md#jsonexceptionout_of_range411) if an "add" operation's target
   location has a parent that is neither an object nor an array.
+- Throws [`out_of_range.413`](../../home/exceptions.md#jsonexceptionout_of_range413) if a "remove" operation's target
+  location has a parent that is neither an object nor an array.
+- Throws [`out_of_range.414`](../../home/exceptions.md#jsonexceptionout_of_range414) if a "move" operation's "from"
+  location is a proper prefix of its "path" location.
 - Throws [`other_error.501`](../../home/exceptions.md#jsonexceptionother_error501) if "test" operation was
   unsuccessful.
 
@@ -72,3 +76,7 @@ function throws an exception.
 - Added in version 3.11.0.
 - Added [`out_of_range.411`](../../home/exceptions.md#jsonexceptionout_of_range411) and stopped relying on an internal assertion when an "add" operation's
   target location has a non-object/non-array parent in version 3.13.0.
+- Added [`out_of_range.413`](../../home/exceptions.md#jsonexceptionout_of_range413) and stopped silently ignoring a "remove" operation whose target
+  location has a non-object/non-array parent in version 3.13.0.
+- Added [`out_of_range.414`](../../home/exceptions.md#jsonexceptionout_of_range414) and rejected a "move" operation whose "from" location is a proper
+  prefix of its "path" location instead of silently producing a corrupted result in version 3.13.0.

docs/mkdocs/docs/home/exceptions.md

@@ -933,6 +933,34 @@ BSON stores the length of documents, arrays, strings, and binary values in a sig
     [`to_bson`](../api/basic_json/to_bson.md) produced documents with negative length prefixes that
     [`from_bson`](../api/basic_json/from_bson.md) rejected.
 
+### json.exception.out_of_range.413
+
+A JSON Patch `remove` operation cannot be applied because the target location's parent is neither an object nor an array. Per [RFC 6902](https://datatracker.ietf.org/doc/html/rfc6902), a `remove` target must reference a member of an existing object or an element of an existing array; a primitive value (string, number, boolean, etc.) or `null` has no members or elements to remove.
+
+!!! failure "Example message"
+
+    ```
+    cannot remove value: the JSON Patch 'remove' target's parent is of type number, but must be an object or array
+    ```
+
+!!! note
+
+    This exception was added in version 3.13.0. Before that, this situation was silently ignored (the `remove` operation had no effect).
+
+### json.exception.out_of_range.414
+
+A JSON Patch `move` operation's `"from"` location is a proper prefix of its `"path"` location. Per [RFC 6902](https://datatracker.ietf.org/doc/html/rfc6902) (section 4.4), a location cannot be moved into one of its own children.
+
+!!! failure "Example message"
+
+    ```
+    cannot move value: 'from' path '/0' is a proper prefix of 'path' '/0/0'
+    ```
+
+!!! note
+
+    This exception was added in version 3.13.0. Before that, this situation could succeed with a corrupted result: for an array target, removing the "from" element before the "add" step shifted subsequent indices, so "path" silently re-resolved to a different element than intended.
+
 ## Further exceptions
 
 This exception is thrown in case of errors that cannot be classified with the

include/nlohmann/json.hpp

@@ -4939,6 +4939,36 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
                 // note erase performs range check
                 parent.erase(json_pointer::template array_index<basic_json_t>(last_path));
             }
+            else
+            {
+                // the parent of a "remove" target must be an object or array
+                // (see #5396)
+                JSON_THROW(out_of_range::create(413, detail::concat("cannot remove value: the JSON Patch 'remove' target's parent is of type ", parent.type_name(), ", but must be an object or array"), &parent));
+            }
+        };
+
+        // RFC 6902 (section 4.4) forbids "from" from being a proper prefix
+        // of "path" for a "move" operation: a location cannot be moved into
+        // one of its own children. Compares reference tokens (already
+        // unescaped by json_pointer's parser) rather than the raw pointer
+        // strings, since a token may itself contain an escaped '/' or '~'
+        // that would defeat a naive string-prefix comparison. "from" equal
+        // to "path" is *not* a proper prefix and must return false.
+        const auto is_proper_prefix = [](const json_pointer & from, const json_pointer & to)
+        {
+            const auto from_size = from.reference_tokens.size();
+            if (from_size >= to.reference_tokens.size())
+            {
+                return false;
+            }
+            for (std::size_t i = 0; i < from_size; ++i)
+            {
+                if (!(from.reference_tokens[i] == to.reference_tokens[i]))
+                {
+                    return false;
+                }
+            }
+            return true;
         };
 
         // type check: top level value must be an array
@@ -5016,6 +5046,11 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
                     const auto from_path = get_value("move", "from", true).template get<string_t>();
                     json_pointer from_ptr(from_path);
 
+                    if (JSON_HEDLEY_UNLIKELY(is_proper_prefix(from_ptr, ptr)))
+                    {
+                        JSON_THROW(out_of_range::create(414, detail::concat("cannot move value: 'from' path '", from_path, "' is a proper prefix of 'path' '", path, "'"), &result));
+                    }
+
                     // the "from" location must exist - use at()
                     basic_json const v = result.at(from_ptr);
 

single_include/nlohmann/json.hpp

@@ -26367,6 +26367,36 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
                 // note erase performs range check
                 parent.erase(json_pointer::template array_index<basic_json_t>(last_path));
             }
+            else
+            {
+                // the parent of a "remove" target must be an object or array
+                // (see #5396)
+                JSON_THROW(out_of_range::create(413, detail::concat("cannot remove value: the JSON Patch 'remove' target's parent is of type ", parent.type_name(), ", but must be an object or array"), &parent));
+            }
+        };
+
+        // RFC 6902 (section 4.4) forbids "from" from being a proper prefix
+        // of "path" for a "move" operation: a location cannot be moved into
+        // one of its own children. Compares reference tokens (already
+        // unescaped by json_pointer's parser) rather than the raw pointer
+        // strings, since a token may itself contain an escaped '/' or '~'
+        // that would defeat a naive string-prefix comparison. "from" equal
+        // to "path" is *not* a proper prefix and must return false.
+        const auto is_proper_prefix = [](const json_pointer & from, const json_pointer & to)
+        {
+            const auto from_size = from.reference_tokens.size();
+            if (from_size >= to.reference_tokens.size())
+            {
+                return false;
+            }
+            for (std::size_t i = 0; i < from_size; ++i)
+            {
+                if (!(from.reference_tokens[i] == to.reference_tokens[i]))
+                {
+                    return false;
+                }
+            }
+            return true;
         };
 
         // type check: top level value must be an array
@@ -26444,6 +26474,11 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
                     const auto from_path = get_value("move", "from", true).template get<string_t>();
                     json_pointer from_ptr(from_path);
 
+                    if (JSON_HEDLEY_UNLIKELY(is_proper_prefix(from_ptr, ptr)))
+                    {
+                        JSON_THROW(out_of_range::create(414, detail::concat("cannot move value: 'from' path '", from_path, "' is a proper prefix of 'path' '", path, "'"), &result));
+                    }
+
                     // the "from" location must exist - use at()
                     basic_json const v = result.at(from_ptr);
 

tests/src/unit-json_patch.cpp

@@ -1389,6 +1389,192 @@ TEST_CASE("JSON patch - add to a primitive parent (regression #4292)")
     }
 }
 
+TEST_CASE("JSON patch - remove with primitive or null parent (regression #5396)")
+{
+    // Regression test for https://github.com/nlohmann/json/issues/5396
+    //
+    // RFC 6902 (§4.2) requires the target location of a "remove" operation
+    // to exist. When the target's parent resolves to a primitive value or
+    // null, the operation must fail. Previously operation_remove silently
+    // did nothing in this case (neither the "is_object" nor the "is_array"
+    // branch matched, and there was no final "else"), so the patch appeared
+    // to succeed without changing the document. It now throws
+    // out_of_range.413.
+
+    SECTION("parent is a primitive (number)")
+    {
+        json const doc = {{"a", 1}};
+        json const patch = {{{"op", "remove"}, {"path", "/a/b"}}};
+#if JSON_DIAGNOSTICS
+        CHECK_THROWS_WITH_AS(doc.patch(patch), "[json.exception.out_of_range.413] (/a) cannot remove value: the JSON Patch 'remove' target's parent is of type number, but must be an object or array", json::out_of_range&);
+#else
+        CHECK_THROWS_WITH_AS(doc.patch(patch), "[json.exception.out_of_range.413] cannot remove value: the JSON Patch 'remove' target's parent is of type number, but must be an object or array", json::out_of_range&);
+#endif
+    }
+
+    SECTION("parent is a primitive (string)")
+    {
+        json const doc = {{"foo", {{"bar", "a string"}}}};
+        json const patch = {{{"op", "remove"}, {"path", "/foo/bar/baz"}}};
+#if JSON_DIAGNOSTICS
+        CHECK_THROWS_WITH_AS(doc.patch(patch), "[json.exception.out_of_range.413] (/foo/bar) cannot remove value: the JSON Patch 'remove' target's parent is of type string, but must be an object or array", json::out_of_range&);
+#else
+        CHECK_THROWS_WITH_AS(doc.patch(patch), "[json.exception.out_of_range.413] cannot remove value: the JSON Patch 'remove' target's parent is of type string, but must be an object or array", json::out_of_range&);
+#endif
+    }
+
+    SECTION("top-level document is null")
+    {
+        json const doc = nullptr;
+        json const patch = {{{"op", "remove"}, {"path", "/a"}}};
+        CHECK_THROWS_WITH_AS(doc.patch(patch), "[json.exception.out_of_range.413] cannot remove value: the JSON Patch 'remove' target's parent is of type null, but must be an object or array", json::out_of_range&);
+    }
+
+    SECTION("legitimate removes still work")
+    {
+        // object member
+        json const doc1 = {{"a", 1}, {"b", 2}};
+        json const patch1 = {{{"op", "remove"}, {"path", "/a"}}};
+        CHECK(doc1.patch(patch1) == json({{"b", 2}}));
+
+        // array element
+        json const doc2 = R"([1, 2, 3])"_json;
+        json const patch2 = {{{"op", "remove"}, {"path", "/1"}}};
+        CHECK(doc2.patch(patch2) == R"([1, 3])"_json);
+    }
+}
+
+TEST_CASE("JSON patch - move where 'from' is a proper prefix of 'path' (regression #5397)")
+{
+    // Regression test for https://github.com/nlohmann/json/issues/5397
+    //
+    // RFC 6902 (§4.4) forbids "from" from being a proper prefix of "path"
+    // for a "move" operation: "a location cannot be moved into one of its
+    // children." "move" is implemented as remove-then-add; for an object
+    // target this happened to throw anyway as a side effect of the "add"
+    // step re-resolving through the now-removed parent, but for an array
+    // target the removal shifted subsequent indices, so "path" silently
+    // re-resolved to a different element and the operation "succeeded"
+    // with a corrupted result. It now throws out_of_range.414 for both
+    // object and array targets.
+
+    SECTION("array target (from the issue)")
+    {
+        json const doc = R"([[1,2],[3]])"_json;
+        json const patch = {{{"op", "move"}, {"from", "/0"}, {"path", "/0/0"}}};
+#if JSON_DIAGNOSTIC_POSITIONS
+        CHECK_THROWS_WITH_AS(doc.patch(patch), "[json.exception.out_of_range.414] (bytes 0-11) cannot move value: 'from' path '/0' is a proper prefix of 'path' '/0/0'", json::out_of_range&);
+#else
+        CHECK_THROWS_WITH_AS(doc.patch(patch), "[json.exception.out_of_range.414] cannot move value: 'from' path '/0' is a proper prefix of 'path' '/0/0'", json::out_of_range&);
+#endif
+    }
+
+    SECTION("object target")
+    {
+        json const doc = R"({"a": {"b": 1}})"_json;
+        json const patch = {{{"op", "move"}, {"from", "/a"}, {"path", "/a/b"}}};
+#if JSON_DIAGNOSTIC_POSITIONS
+        CHECK_THROWS_WITH_AS(doc.patch(patch), "[json.exception.out_of_range.414] (bytes 0-15) cannot move value: 'from' path '/a' is a proper prefix of 'path' '/a/b'", json::out_of_range&);
+#else
+        CHECK_THROWS_WITH_AS(doc.patch(patch), "[json.exception.out_of_range.414] cannot move value: 'from' path '/a' is a proper prefix of 'path' '/a/b'", json::out_of_range&);
+#endif
+    }
+
+    SECTION("from == path is not a proper prefix and must not be rejected")
+    {
+        // "from" equal to "path" is a no-op move; it is not a *proper*
+        // prefix relationship, so this new check must not reject it.
+        json const doc = R"({"a": 1, "b": 2})"_json;
+        json const patch = {{{"op", "move"}, {"from", "/a"}, {"path", "/a"}}};
+        CHECK(doc.patch(patch) == doc);
+    }
+
+    SECTION("raw string prefix that is not a pointer-token prefix must be allowed")
+    {
+        // "/ab" is a string-prefix of "/abc/x" as raw text, but "ab" and
+        // "abc" are different reference tokens, so this is NOT a
+        // pointer-token prefix relationship and the move must succeed.
+        // This is the key case proving the check compares tokens, not
+        // raw pointer text (a naive std::string prefix/rfind check on
+        // the undecoded pointer would wrongly reject this).
+        json const doc = R"({"ab": 1, "abc": {"x": 2}})"_json;
+        json const patch = {{{"op", "move"}, {"from", "/ab"}, {"path", "/abc/x"}}};
+        json const result = R"({"abc": {"x": 1}})"_json;
+        CHECK(doc.patch(patch) == result);
+    }
+
+    SECTION("escaped reference tokens are compared unescaped")
+    {
+        // "from" is the single token "a/b" (escaped as "a~1b"); "path"
+        // addresses member "x" of that same value, so "from" is a
+        // proper (token-level) prefix of "path" and must be rejected.
+        json const doc = R"({"a/b": {"x": 1}})"_json;
+        json const patch = {{{"op", "move"}, {"from", "/a~1b"}, {"path", "/a~1b/x"}}};
+#if JSON_DIAGNOSTIC_POSITIONS
+        CHECK_THROWS_WITH_AS(doc.patch(patch), "[json.exception.out_of_range.414] (bytes 0-17) cannot move value: 'from' path '/a~1b' is a proper prefix of 'path' '/a~1b/x'", json::out_of_range&);
+#else
+        CHECK_THROWS_WITH_AS(doc.patch(patch), "[json.exception.out_of_range.414] cannot move value: 'from' path '/a~1b' is a proper prefix of 'path' '/a~1b/x'", json::out_of_range&);
+#endif
+    }
+
+    SECTION("ordinary valid moves still work")
+    {
+        // unrelated top-level members
+        json const doc1 = R"({"a": 1, "b": 2})"_json;
+        json const patch1 = {{{"op", "move"}, {"from", "/a"}, {"path", "/c"}}};
+        CHECK(doc1.patch(patch1) == R"({"b": 2, "c": 1})"_json);
+
+        // sibling paths that share a textual prefix but are unrelated
+        json const doc2 = R"({"a": {"x": 1}, "b": {"y": 2}})"_json;
+        json const patch2 = {{{"op", "move"}, {"from", "/a/x"}, {"path", "/b/z"}}};
+        CHECK(doc2.patch(patch2) == R"({"a": {}, "b": {"y": 2, "z": 1}})"_json);
+
+        // "path" is a proper prefix of "from" (the reverse relationship,
+        // which RFC 6902 does not forbid)
+        json const doc3 = R"({"a": {"b": 1}})"_json;
+        json const patch3 = {{{"op", "move"}, {"from", "/a/b"}, {"path", "/a"}}};
+        CHECK(doc3.patch(patch3) == R"({"a": 1})"_json);
+    }
+
+    SECTION("root 'from' is a proper prefix of every non-root 'path'")
+    {
+        // the whole document is a proper prefix of any location inside it
+        json const doc = R"({"a": 1})"_json;
+        json const patch = {{{"op", "move"}, {"from", ""}, {"path", "/a"}}};
+#if JSON_DIAGNOSTIC_POSITIONS
+        CHECK_THROWS_WITH_AS(doc.patch(patch), "[json.exception.out_of_range.414] (bytes 0-8) cannot move value: 'from' path '' is a proper prefix of 'path' '/a'", json::out_of_range&);
+#else
+        CHECK_THROWS_WITH_AS(doc.patch(patch), "[json.exception.out_of_range.414] cannot move value: 'from' path '' is a proper prefix of 'path' '/a'", json::out_of_range&);
+#endif
+    }
+
+    SECTION("root 'path' is never a proper prefix violation for a non-root 'from'")
+    {
+        // the reverse of the above: moving a non-root location to the root
+        // is the "path is a prefix of from" relationship, which RFC 6902
+        // permits (already covered generally above; this pins the root
+        // case specifically, since root is the one path with no reference
+        // tokens at all)
+        json const doc = R"({"a": {"b": 1}})"_json;
+        json const patch = {{{"op", "move"}, {"from", "/a"}, {"path", ""}}};
+        CHECK(doc.patch(patch) == R"({"b": 1})"_json);
+    }
+
+    SECTION("the array-append token '-' is an ordinary child token")
+    {
+        // "-" (append-to-array) addresses a location *inside* the array,
+        // so "from" pointing at the array is still a proper prefix of
+        // "path" ending in "-" and must be rejected like any other child.
+        json const doc = R"({"a": [1, 2]})"_json;
+        json const patch = {{{"op", "move"}, {"from", "/a"}, {"path", "/a/-"}}};
+#if JSON_DIAGNOSTIC_POSITIONS
+        CHECK_THROWS_WITH_AS(doc.patch(patch), "[json.exception.out_of_range.414] (bytes 0-13) cannot move value: 'from' path '/a' is a proper prefix of 'path' '/a/-'", json::out_of_range&);
+#else
+        CHECK_THROWS_WITH_AS(doc.patch(patch), "[json.exception.out_of_range.414] cannot move value: 'from' path '/a' is a proper prefix of 'path' '/a/-'", json::out_of_range&);
+#endif
+    }
+}
+
 TEST_CASE("JSON patch - diff emits array removals in descending index order")
 {
     SECTION("array shrunk to empty")

tests/src/unit-ordered_json2.cpp

@@ -1,489 +0,0 @@
-//     __ _____ _____ _____
-//  __|  |   __|     |   | |  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-FileCopyrightText: 2018 Vitaliy Manushkin <agri@akamo.info>
-// SPDX-License-Identifier: MIT
-
-// This file closes a test-coverage gap described in GitHub issue #5421:
-// nlohmann::ordered_json (and other non-default basic_json specializations,
-// such as the alt_string-based one from unit-alt-string.cpp) were never
-// exercised through the binary formats (CBOR/MessagePack/UBJSON/BSON/BJData)
-// or through flatten()/unflatten()/diff()/patch()/merge_patch().
-
-#include "doctest_compatibility.h"
-
-#include <nlohmann/json.hpp>
-
-#include <cstdint>
-#include <string>
-#include <utility>
-#include <vector>
-
-using nlohmann::json;
-using nlohmann::ordered_json;
-
-/////////////////////////////////////////////////////////////////////////////
-// alt_json: a second, independent copy of the custom-string_t basic_json
-// specialization defined in unit-alt-string.cpp.
-//
-// It is duplicated here (rather than shared via a header) because every
-// unit-*.cpp file in this test suite is compiled into its own standalone
-// executable (see tests/CMakeLists.txt), so there is no ODR concern in
-// having the same class name defined in multiple translation units.
-//
-// Two members had to be added relative to the original alt_string
-// (a constructor from std::string, and a find(char, pos) overload) because
-// the original type was never used with the binary writers/readers before
-// this file: BSON's array/document writer converts std::to_string() results
-// and checks for embedded NUL characters via find(char), and the UBJSON/BSON
-// high-precision-number path constructs the SAX string_t argument from a
-// std::string. Neither path is exercised anywhere else in the test suite for
-// this type, which is presumably why the gap was never noticed.
-/////////////////////////////////////////////////////////////////////////////
-
-class alt_string;
-bool operator<(const char* op1, const alt_string& op2) noexcept; // NOLINT(misc-use-internal-linkage)
-void int_to_string(alt_string& target, std::size_t value); // NOLINT(misc-use-internal-linkage)
-
-class alt_string
-{
-  public:
-    using value_type = std::string::value_type;
-
-    static constexpr auto npos = (std::numeric_limits<std::size_t>::max)();
-
-    alt_string(const char* str): str_impl(str) {}
-    alt_string(const char* str, std::size_t count): str_impl(str, count) {}
-    alt_string(std::string str): str_impl(std::move(str)) {}
-    alt_string(size_t count, char chr): str_impl(count, chr) {}
-    alt_string() = default;
-
-    alt_string& append(char ch)
-    {
-        str_impl.push_back(ch);
-        return *this;
-    }
-
-    alt_string& append(const alt_string& str)
-    {
-        str_impl.append(str.str_impl);
-        return *this;
-    }
-
-    alt_string& append(const char* s, std::size_t length)
-    {
-        str_impl.append(s, length);
-        return *this;
-    }
-
-    void push_back(char c)
-    {
-        str_impl.push_back(c);
-    }
-
-    template <typename op_type>
-    bool operator==(const op_type& op) const
-    {
-        return str_impl == op;
-    }
-
-    bool operator==(const alt_string& op) const
-    {
-        return str_impl == op.str_impl;
-    }
-
-    template <typename op_type>
-    bool operator!=(const op_type& op) const
-    {
-        return str_impl != op;
-    }
-
-    bool operator!=(const alt_string& op) const
-    {
-        return str_impl != op.str_impl;
-    }
-
-    std::size_t size() const noexcept
-    {
-        return str_impl.size();
-    }
-
-    void resize(std::size_t n)
-    {
-        str_impl.resize(n);
-    }
-
-    void resize(std::size_t n, char c)
-    {
-        str_impl.resize(n, c);
-    }
-
-    template <typename op_type>
-    bool operator<(const op_type& op) const noexcept
-    {
-        return str_impl < op;
-    }
-
-    bool operator<(const alt_string& op) const noexcept
-    {
-        return str_impl < op.str_impl;
-    }
-
-    const char* c_str() const
-    {
-        return str_impl.c_str();
-    }
-
-    char& operator[](std::size_t index)
-    {
-        return str_impl[index];
-    }
-
-    const char& operator[](std::size_t index) const
-    {
-        return str_impl[index];
-    }
-
-    char& back()
-    {
-        return str_impl.back();
-    }
-
-    const char& back() const
-    {
-        return str_impl.back();
-    }
-
-    void clear()
-    {
-        str_impl.clear();
-    }
-
-    const value_type* data() const
-    {
-        return str_impl.data();
-    }
-
-    bool empty() const
-    {
-        return str_impl.empty();
-    }
-
-    std::size_t find(const alt_string& str, std::size_t pos = 0) const
-    {
-        return str_impl.find(str.str_impl, pos);
-    }
-
-    // needed by binary_writer's BSON support, which probes string keys for
-    // embedded NUL characters via find(char)
-    std::size_t find(char c, std::size_t pos = 0) const
-    {
-        return str_impl.find(c, pos);
-    }
-
-    std::size_t find_first_of(char c, std::size_t pos = 0) const
-    {
-        return str_impl.find_first_of(c, pos);
-    }
-
-    alt_string substr(std::size_t pos = 0, std::size_t count = npos) const
-    {
-        const std::string s = str_impl.substr(pos, count);
-        return {s.data(), s.size()};
-    }
-
-    alt_string& replace(std::size_t pos, std::size_t count, const alt_string& str)
-    {
-        str_impl.replace(pos, count, str.str_impl);
-        return *this;
-    }
-
-    void reserve(std::size_t new_cap = 0)
-    {
-        str_impl.reserve(new_cap);
-    }
-
-  private:
-    std::string str_impl {}; // NOLINT(readability-redundant-member-init)
-
-    friend bool operator<(const char* /*op1*/, const alt_string& /*op2*/) noexcept;
-};
-
-void int_to_string(alt_string& target, std::size_t value)
-{
-    target = std::to_string(value).c_str();
-}
-
-using alt_json = nlohmann::basic_json <
-                 std::map,
-                 std::vector,
-                 alt_string,
-                 bool,
-                 std::int64_t,
-                 std::uint64_t,
-                 double,
-                 std::allocator,
-                 nlohmann::adl_serializer >;
-
-bool operator<(const char* op1, const alt_string& op2) noexcept
-{
-    return op1 < op2.str_impl;
-}
-
-namespace
-{
-
-// collects the object keys of j, in iteration order
-std::vector<std::string> collect_keys(const ordered_json& j)
-{
-    std::vector<std::string> result;
-    for (auto it = j.cbegin(); it != j.cend(); ++it)
-    {
-        result.push_back(it.key());
-    }
-    return result;
-}
-
-// a nested object/array value with keys inserted in non-alphabetical order,
-// used to check both round-trip equality and (for ordered_json) that
-// insertion order survives a trip through a binary format
-ordered_json make_rich_ordered_json()
-{
-    ordered_json j;
-    j["zebra"] = 1;
-    j["apple"] = ordered_json::array({1, 2, 3});
-    j["mango"]["z_nested"] = true;
-    j["mango"]["a_nested"] = nullptr;
-    j["banana"] = "some text";
-    j["cherry"] = 3.14;
-    return j;
-}
-
-alt_json make_rich_alt_json()
-{
-    alt_json j;
-    j["zebra"] = 1;
-    j["apple"] = alt_json::array({1, 2, 3});
-    j["mango"]["z_nested"] = true;
-    j["mango"]["a_nested"] = nullptr;
-    j["banana"] = "some text";
-    j["cherry"] = 3.14;
-    return j;
-}
-
-} // namespace
-
-TEST_CASE("ordered_json across binary formats")
-{
-    const ordered_json original = make_rich_ordered_json();
-    const std::vector<std::string> original_keys = collect_keys(original);
-    const std::vector<std::string> original_mango_keys = collect_keys(original["mango"]);
-
-    SECTION("CBOR")
-    {
-        const auto bytes = ordered_json::to_cbor(original);
-        const auto restored = ordered_json::from_cbor(bytes);
-        CHECK(restored == original);
-        CHECK(collect_keys(restored) == original_keys);
-        CHECK(collect_keys(restored["mango"]) == original_mango_keys);
-    }
-
-    SECTION("MessagePack")
-    {
-        const auto bytes = ordered_json::to_msgpack(original);
-        const auto restored = ordered_json::from_msgpack(bytes);
-        CHECK(restored == original);
-        CHECK(collect_keys(restored) == original_keys);
-        CHECK(collect_keys(restored["mango"]) == original_mango_keys);
-    }
-
-    SECTION("UBJSON")
-    {
-        const auto bytes = ordered_json::to_ubjson(original);
-        const auto restored = ordered_json::from_ubjson(bytes);
-        CHECK(restored == original);
-        CHECK(collect_keys(restored) == original_keys);
-        CHECK(collect_keys(restored["mango"]) == original_mango_keys);
-    }
-
-    SECTION("BSON")
-    {
-        const auto bytes = ordered_json::to_bson(original);
-        const auto restored = ordered_json::from_bson(bytes);
-        CHECK(restored == original);
-        CHECK(collect_keys(restored) == original_keys);
-        CHECK(collect_keys(restored["mango"]) == original_mango_keys);
-    }
-
-    SECTION("BJData")
-    {
-        const auto bytes = ordered_json::to_bjdata(original);
-        const auto restored = ordered_json::from_bjdata(bytes);
-        CHECK(restored == original);
-        CHECK(collect_keys(restored) == original_keys);
-        CHECK(collect_keys(restored["mango"]) == original_mango_keys);
-    }
-}
-
-TEST_CASE("alt_json (custom string_t) across binary formats")
-{
-    const alt_json original = make_rich_alt_json();
-
-    SECTION("CBOR")
-    {
-        const auto bytes = alt_json::to_cbor(original);
-        const auto restored = alt_json::from_cbor(bytes);
-        CHECK(restored == original);
-    }
-
-    SECTION("MessagePack")
-    {
-        const auto bytes = alt_json::to_msgpack(original);
-        const auto restored = alt_json::from_msgpack(bytes);
-        CHECK(restored == original);
-    }
-
-    SECTION("UBJSON")
-    {
-        const auto bytes = alt_json::to_ubjson(original);
-        const auto restored = alt_json::from_ubjson(bytes);
-        CHECK(restored == original);
-    }
-
-    SECTION("BSON")
-    {
-        const auto bytes = alt_json::to_bson(original);
-        const auto restored = alt_json::from_bson(bytes);
-        CHECK(restored == original);
-    }
-
-    SECTION("BJData")
-    {
-        const auto bytes = alt_json::to_bjdata(original);
-        const auto restored = alt_json::from_bjdata(bytes);
-        CHECK(restored == original);
-    }
-}
-
-TEST_CASE("ordered_json operator== is sensitive to key order")
-{
-    // Unlike nlohmann::json (whose object_t is a std::map, so equality never
-    // depends on insertion order), ordered_json's object_t (ordered_map) is a
-    // std::vector<std::pair<Key, T>> under the hood, and does not define its
-    // own operator==: it inherits std::vector's element-wise comparison. As a
-    // result, two ordered_json objects holding the very same key/value pairs
-    // in different insertion order compare *unequal*. This is the property
-    // that makes the round-trip `CHECK(restored == original)` checks above a
-    // meaningful order-preservation check by themselves (the explicit
-    // collect_keys() comparisons make that check explicit/readable, and
-    // guard against this operator== behavior ever changing).
-    ordered_json a;
-    a["x"] = 1;
-    a["y"] = 2;
-
-    ordered_json b;
-    b["y"] = 2;
-    b["x"] = 1;
-
-    CHECK(a.size() == b.size());
-    CHECK(a["x"] == b["x"]);
-    CHECK(a["y"] == b["y"]);
-    CHECK_FALSE(a == b);
-}
-
-TEST_CASE("duplicate keys in a binary-encoded object")
-{
-    // CBOR encoding of a map with two entries under the same key "a": {"a": 1, "a": 2}
-    const std::vector<std::uint8_t> cbor_bytes
-    {
-        0xA2, 0x61, 'a', 0x01, 0x61, 'a', 0x02
-    };
-
-    // Both json (std::map, via operator[]) and ordered_json (ordered_map, via
-    // operator[]) build binary-decoded objects by looking up/creating the
-    // entry for each incoming key and then assigning the value into it. This
-    // means a repeated key does *not* produce two entries in either case;
-    // instead, the *first* occurrence's position is kept (relevant only for
-    // ordered_json) while the *last* occurrence's value wins (for both) --
-    // this matches operator[]'s "assign the referenced slot" semantics, and
-    // is worth noting because it differs from the initializer-list
-    // construction path (`ordered_json{{"a",1},{"a",2}}`), which builds
-    // through insert()/emplace() and therefore keeps the *first* value, not
-    // the last (see the "There are no dup keys..." case in
-    // unit-ordered_json.cpp).
-    const auto j = json::from_cbor(cbor_bytes);
-    const auto oj = ordered_json::from_cbor(cbor_bytes);
-
-    CHECK(j.size() == 1);
-    CHECK(oj.size() == 1);
-    CHECK(j["a"] == 2);
-    CHECK(oj["a"] == 2);
-    CHECK(j == json(oj));
-}
-
-TEST_CASE("ordered_json through flatten/unflatten")
-{
-    const ordered_json original = make_rich_ordered_json();
-    const std::vector<std::string> original_keys = collect_keys(original);
-    const std::vector<std::string> original_mango_keys = collect_keys(original["mango"]);
-
-    const ordered_json flat = original.flatten();
-    const ordered_json unflattened = flat.unflatten();
-
-    CHECK(unflattened == original);
-    // flatten() walks the value depth-first in iteration order and
-    // unflatten() re-inserts each flattened key via operator[] in the flat
-    // object's iteration order, so for ordered_json the original key order
-    // (both top-level and nested) is preserved end-to-end.
-    CHECK(collect_keys(unflattened) == original_keys);
-    CHECK(collect_keys(unflattened["mango"]) == original_mango_keys);
-}
-
-TEST_CASE("ordered_json through diff/patch/patch_inplace")
-{
-    ordered_json original;
-    original["one"] = 1;
-    original["two"] = 2;
-    original["three"] = 3;
-
-    ordered_json target = original;
-    target["one"] = 100;      // replace
-    target.erase("two");      // remove
-    target["four"] = 4;       // add
-
-    const ordered_json patch = ordered_json::diff(original, target);
-
-    SECTION("patch")
-    {
-        const ordered_json patched = original.patch(patch);
-        CHECK(patched == target);
-    }
-
-    SECTION("patch_inplace")
-    {
-        ordered_json copy = original;
-        copy.patch_inplace(patch);
-        CHECK(copy == target);
-    }
-}
-
-TEST_CASE("ordered_json through merge_patch")
-{
-    ordered_json original;
-    original["a"] = 1;
-    original["b"] = 2;
-
-    const ordered_json patch = {{"b", nullptr}, {"c", 3}};
-
-    original.merge_patch(patch);
-
-    ordered_json expected;
-    expected["a"] = 1;
-    expected["c"] = 3;
-
-    CHECK(original == expected);
-    CHECK(collect_keys(original) == collect_keys(expected));
-}

tests/src/unit-std-format.cpp

@@ -17,7 +17,6 @@
 
 #include <nlohmann/json.hpp>
 using json = nlohmann::json;
-using ordered_json = nlohmann::ordered_json;
 
 // JSON_HAS_CPP_20 (do not remove; see note at top of file)
 #if JSON_HAS_STD_FORMAT
@@ -94,16 +93,4 @@ TEST_CASE("std::formatter<nlohmann::json>")
     }
 }
 
-TEST_CASE("std::formatter<nlohmann::ordered_json>")
-{
-    // spot-check a non-default basic_json instantiation, since the formatter
-    // is written against the generic NLOHMANN_BASIC_JSON_TPL_DECLARATION
-    // template and must actually instantiate (and behave correctly) for
-    // template arguments other than nlohmann::json
-    const ordered_json j = {{"foo", 1}, {"bar", {1, 2, 3}}};
-    CHECK(std::format("{}", j) == j.dump());
-    CHECK(std::format("{:#}", j) == j.dump(4));
-    CHECK(std::format("{:2}", j) == j.dump(2));
-}
-
 #endif