🔀 merged #415 (fix for #414)

README.md

@@ -823,7 +823,7 @@ I deeply appreciate the help of the following people.
 - [Martin Hořeňovský](https://github.com/horenmar) found a way for a 2x speedup for the compilation time of the test suite.
 - [ukhegg](https://github.com/ukhegg) found proposed an improvement for the examples section.
 - [rswanson-ihi](https://github.com/rswanson-ihi) noted a type in the README.
-- 
+- [Mihai Stan](https://github.com/stanmihai4) fixed a bug in the comparison with `nullptr`s.
 
 
 Thanks a lot for helping out! Please [let me know](mailto:mail@nlohmann.me) if I forgot someone.
@@ -857,7 +857,7 @@ $ make json_unit -Ctest
 $ ./test/json_unit "*""
 
 ===============================================================================
-All tests passed (11202562 assertions in 47 test cases)
+All tests passed (11202588 assertions in 47 test cases)
 ```
 
 Alternatively, you can use [CMake](https://cmake.org) and run

src/json.hpp

@@ -5963,34 +5963,24 @@ class basic_json
 
     /*!
     @brief comparison: equal
-
+    @copydoc operator==(const_reference, const_reference)
-    The functions compares the given JSON value against a null pointer. As the
-    null pointer can be used to initialize a JSON value to null, a comparison
-    of JSON value @a v with a null pointer should be equivalent to call
-    `v.is_null()`.
-
-    @param[in] v  JSON value to consider
-    @return whether @a v is null
-
-    @complexity Constant.
-
-    @liveexample{The example compares several JSON types to the null pointer.
-    ,operator__equal__nullptr_t}
-
-    @since version 1.0.0
     */
-    friend bool operator==(const_reference v, std::nullptr_t) noexcept
+    template<typename ScalarType, typename std::enable_if<
+                 std::is_scalar<ScalarType>::value, int>::type = 0>
+    friend bool operator==(const_reference lhs, const ScalarType rhs) noexcept
     {
-        return v.is_null();
+        return (lhs == basic_json(rhs));
     }
 
     /*!
     @brief comparison: equal
-    @copydoc operator==(const_reference, std::nullptr_t)
+    @copydoc operator==(const_reference, const_reference)
     */
-    friend bool operator==(std::nullptr_t, const_reference v) noexcept
+    template<typename ScalarType, typename std::enable_if<
+                 std::is_scalar<ScalarType>::value, int>::type = 0>
+    friend bool operator==(const ScalarType lhs, const_reference rhs) noexcept
     {
-        return v.is_null();
+        return (basic_json(lhs) == rhs);
     }
 
     /*!
@@ -6016,34 +6006,24 @@ class basic_json
 
     /*!
     @brief comparison: not equal
-
+    @copydoc operator!=(const_reference, const_reference)
-    The functions compares the given JSON value against a null pointer. As the
-    null pointer can be used to initialize a JSON value to null, a comparison
-    of JSON value @a v with a null pointer should be equivalent to call
-    `not v.is_null()`.
-
-    @param[in] v  JSON value to consider
-    @return whether @a v is not null
-
-    @complexity Constant.
-
-    @liveexample{The example compares several JSON types to the null pointer.
-    ,operator__notequal__nullptr_t}
-
-    @since version 1.0.0
     */
-    friend bool operator!=(const_reference v, std::nullptr_t) noexcept
+    template<typename ScalarType, typename std::enable_if<
+                 std::is_scalar<ScalarType>::value, int>::type = 0>
+    friend bool operator!=(const_reference lhs, const ScalarType rhs) noexcept
     {
-        return not v.is_null();
+        return (lhs != basic_json(rhs));
     }
 
     /*!
     @brief comparison: not equal
-    @copydoc operator!=(const_reference, std::nullptr_t)
+    @copydoc operator!=(const_reference, const_reference)
     */
-    friend bool operator!=(std::nullptr_t, const_reference v) noexcept
+    template<typename ScalarType, typename std::enable_if<
+                 std::is_scalar<ScalarType>::value, int>::type = 0>
+    friend bool operator!=(const ScalarType lhs, const_reference rhs) noexcept
     {
-        return not v.is_null();
+        return (basic_json(lhs) != rhs);
     }
 
     /*!

src/json.hpp.re2c

@@ -5963,34 +5963,24 @@ class basic_json
 
     /*!
     @brief comparison: equal
-
+    @copydoc operator==(const_reference, const_reference)
-    The functions compares the given JSON value against a null pointer. As the
-    null pointer can be used to initialize a JSON value to null, a comparison
-    of JSON value @a v with a null pointer should be equivalent to call
-    `v.is_null()`.
-
-    @param[in] v  JSON value to consider
-    @return whether @a v is null
-
-    @complexity Constant.
-
-    @liveexample{The example compares several JSON types to the null pointer.
-    ,operator__equal__nullptr_t}
-
-    @since version 1.0.0
     */
-    friend bool operator==(const_reference v, std::nullptr_t) noexcept
+    template<typename ScalarType, typename std::enable_if<
+                 std::is_scalar<ScalarType>::value, int>::type = 0>
+    friend bool operator==(const_reference lhs, const ScalarType rhs) noexcept
     {
-        return v.is_null();
+        return (lhs == basic_json(rhs));
     }
 
     /*!
     @brief comparison: equal
-    @copydoc operator==(const_reference, std::nullptr_t)
+    @copydoc operator==(const_reference, const_reference)
     */
-    friend bool operator==(std::nullptr_t, const_reference v) noexcept
+    template<typename ScalarType, typename std::enable_if<
+                 std::is_scalar<ScalarType>::value, int>::type = 0>
+    friend bool operator==(const ScalarType lhs, const_reference rhs) noexcept
     {
-        return v.is_null();
+        return (basic_json(lhs) == rhs);
     }
 
     /*!
@@ -6016,34 +6006,24 @@ class basic_json
 
     /*!
     @brief comparison: not equal
-
+    @copydoc operator!=(const_reference, const_reference)
-    The functions compares the given JSON value against a null pointer. As the
-    null pointer can be used to initialize a JSON value to null, a comparison
-    of JSON value @a v with a null pointer should be equivalent to call
-    `not v.is_null()`.
-
-    @param[in] v  JSON value to consider
-    @return whether @a v is not null
-
-    @complexity Constant.
-
-    @liveexample{The example compares several JSON types to the null pointer.
-    ,operator__notequal__nullptr_t}
-
-    @since version 1.0.0
     */
-    friend bool operator!=(const_reference v, std::nullptr_t) noexcept
+    template<typename ScalarType, typename std::enable_if<
+                 std::is_scalar<ScalarType>::value, int>::type = 0>
+    friend bool operator!=(const_reference lhs, const ScalarType rhs) noexcept
     {
-        return not v.is_null();
+        return (lhs != basic_json(rhs));
     }
 
     /*!
     @brief comparison: not equal
-    @copydoc operator!=(const_reference, std::nullptr_t)
+    @copydoc operator!=(const_reference, const_reference)
     */
-    friend bool operator!=(std::nullptr_t, const_reference v) noexcept
+    template<typename ScalarType, typename std::enable_if<
+                 std::is_scalar<ScalarType>::value, int>::type = 0>
+    friend bool operator!=(const ScalarType lhs, const_reference rhs) noexcept
     {
-        return not v.is_null();
+        return (basic_json(lhs) != rhs);
     }
 
     /*!

test/src/unit-regression.cpp

@@ -698,6 +698,24 @@ TEST_CASE("regression tests")
         CHECK_THROWS_AS(json::from_cbor(vec3), std::out_of_range);
     }
 
+    SECTION("issue #414 - compare with literal 0)")
+    {
+#define CHECK_TYPE(v) \
+    CHECK((json(v) == v));\
+    CHECK((v == json(v)));\
+    CHECK_FALSE((json(v) != v));\
+    CHECK_FALSE((v != json(v)));
+
+        CHECK_TYPE(nullptr);
+        CHECK_TYPE(0);
+        CHECK_TYPE(0u);
+        CHECK_TYPE(0L);
+        CHECK_TYPE(0.0);
+        CHECK_TYPE("");
+
+#undef CHECK_TYPE
+    }
+
     SECTION("issue #416 - Use-of-uninitialized-value (OSS-Fuzz issue 377)")
     {
         // original test case