Fix CI: name the unsigned overload type through template parameters

basic_json used number_unsigned_overload_t<basic_json> while the class was
still incomplete. MSVC rejected it as a recursive alias declaration and GCC
4.9, 5 and 7 crashed with an internal compiler error. basic_json now uses
number_unsigned_overload_type<NumberIntegerType, NumberUnsignedType>, which
also makes the GCC 5 workaround in the patch test unnecessary.

Infer reported a null dereference for the number_unsigned case in
from_json, which cannot happen for a basic_json whose number_unsigned_t is
number_integer_t; assert it.

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

include/nlohmann/detail/conversions/from_json.hpp

@@ -80,7 +80,11 @@ void get_arithmetic_value(const BasicJsonType& j, ArithmeticType& val)
     {
         case value_t::number_unsigned:
         {
-            val = static_cast<ArithmeticType>(*j.template get_ptr<const typename BasicJsonType::number_unsigned_t*>());
+            // never null: a basic_json whose number_unsigned_t is number_integer_t
+            // stores no number_unsigned values (#2573)
+            const auto* ptr = j.template get_ptr<const typename BasicJsonType::number_unsigned_t*>();
+            JSON_ASSERT(ptr != nullptr);
+            val = static_cast<ArithmeticType>(*ptr);
             break;
         }
         case value_t::number_integer:
@@ -406,7 +410,11 @@ inline void from_json(const BasicJsonType& j, ArithmeticType& val)
     {
         case value_t::number_unsigned:
         {
-            val = static_cast<ArithmeticType>(*j.template get_ptr<const typename BasicJsonType::number_unsigned_t*>());
+            // never null: a basic_json whose number_unsigned_t is number_integer_t
+            // stores no number_unsigned values (#2573)
+            const auto* ptr = j.template get_ptr<const typename BasicJsonType::number_unsigned_t*>();
+            JSON_ASSERT(ptr != nullptr);
+            val = static_cast<ArithmeticType>(*ptr);
             break;
         }
         case value_t::number_integer:

include/nlohmann/detail/meta/type_traits.hpp

@@ -1042,13 +1042,20 @@ using bool_constant = std::integral_constant<bool, Value>;
 // number_integer (#2573).
 struct same_as_number_integer_type {};
 
+// NumberUnsignedType, or same_as_number_integer_type if it is the same type as
+// NumberIntegerType; basic_json uses this one, as it cannot name its own member
+// types through an incomplete basic_json (MSVC reports a recursive alias, and
+// old GCC versions crash)
+template<typename NumberIntegerType, typename NumberUnsignedType>
+using number_unsigned_overload_type = typename std::conditional <
+                                      std::is_same<NumberIntegerType, NumberUnsignedType>::value,
+                                      same_as_number_integer_type,
+                                      NumberUnsignedType >::type;
+
 // number_unsigned_t of BasicJsonType, or same_as_number_integer_type if it is
 // the same type as number_integer_t
 template<typename BasicJsonType>
-using number_unsigned_overload_t = typename std::conditional <
-                                   std::is_same<typename BasicJsonType::number_integer_t, typename BasicJsonType::number_unsigned_t>::value,
-                                   same_as_number_integer_type,
-                                   typename BasicJsonType::number_unsigned_t >::type;
+using number_unsigned_overload_t = number_unsigned_overload_type<typename BasicJsonType::number_integer_t, typename BasicJsonType::number_unsigned_t>;
 
 ///////////////////////////////////////////////////////////////////////////////
 // is_c_string

include/nlohmann/json.hpp

@@ -590,7 +590,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
         /// constructor for numbers (integer)
         json_value(number_integer_t v) noexcept : number_integer(v) {}
         /// constructor for numbers (unsigned); takes a placeholder if number_unsigned_t is number_integer_t
-        json_value(detail::number_unsigned_overload_t<basic_json> v) noexcept : number_unsigned(v) {}
+        json_value(detail::number_unsigned_overload_type<NumberIntegerType, NumberUnsignedType> v) noexcept : number_unsigned(v) {}
         /// constructor for numbers (floating-point)
         json_value(number_float_t v) noexcept : number_float(v) {}
         /// constructor for empty values of a given type
@@ -2863,14 +2863,14 @@ public:
 
     /// get a pointer to the value (unsigned number); takes a placeholder if
     /// number_unsigned_t is number_integer_t (the integer overload handles it then)
-    number_unsigned_t* get_impl_ptr(detail::number_unsigned_overload_t<basic_json>* /*unused*/) noexcept
+    number_unsigned_t* get_impl_ptr(detail::number_unsigned_overload_type<NumberIntegerType, NumberUnsignedType>* /*unused*/) noexcept
     {
         return is_number_unsigned() ? &m_data.m_value.number_unsigned : nullptr;
     }
 
     /// get a pointer to the value (unsigned number); takes a placeholder if
     /// number_unsigned_t is number_integer_t (the integer overload handles it then)
-    constexpr const number_unsigned_t* get_impl_ptr(const detail::number_unsigned_overload_t<basic_json>* /*unused*/) const noexcept
+    constexpr const number_unsigned_t* get_impl_ptr(const detail::number_unsigned_overload_type<NumberIntegerType, NumberUnsignedType>* /*unused*/) const noexcept
     {
         return is_number_unsigned() ? &m_data.m_value.number_unsigned : nullptr;
     }

single_include/nlohmann/json.hpp

@@ -5046,13 +5046,20 @@ using bool_constant = std::integral_constant<bool, Value>;
 // number_integer (#2573).
 struct same_as_number_integer_type {};
 
+// NumberUnsignedType, or same_as_number_integer_type if it is the same type as
+// NumberIntegerType; basic_json uses this one, as it cannot name its own member
+// types through an incomplete basic_json (MSVC reports a recursive alias, and
+// old GCC versions crash)
+template<typename NumberIntegerType, typename NumberUnsignedType>
+using number_unsigned_overload_type = typename std::conditional <
+                                      std::is_same<NumberIntegerType, NumberUnsignedType>::value,
+                                      same_as_number_integer_type,
+                                      NumberUnsignedType >::type;
+
 // number_unsigned_t of BasicJsonType, or same_as_number_integer_type if it is
 // the same type as number_integer_t
 template<typename BasicJsonType>
-using number_unsigned_overload_t = typename std::conditional <
-                                   std::is_same<typename BasicJsonType::number_integer_t, typename BasicJsonType::number_unsigned_t>::value,
-                                   same_as_number_integer_type,
-                                   typename BasicJsonType::number_unsigned_t >::type;
+using number_unsigned_overload_t = number_unsigned_overload_type<typename BasicJsonType::number_integer_t, typename BasicJsonType::number_unsigned_t>;
 
 ///////////////////////////////////////////////////////////////////////////////
 // is_c_string
@@ -5806,7 +5813,11 @@ void get_arithmetic_value(const BasicJsonType& j, ArithmeticType& val)
     {
         case value_t::number_unsigned:
         {
-            val = static_cast<ArithmeticType>(*j.template get_ptr<const typename BasicJsonType::number_unsigned_t*>());
+            // never null: a basic_json whose number_unsigned_t is number_integer_t
+            // stores no number_unsigned values (#2573)
+            const auto* ptr = j.template get_ptr<const typename BasicJsonType::number_unsigned_t*>();
+            JSON_ASSERT(ptr != nullptr);
+            val = static_cast<ArithmeticType>(*ptr);
             break;
         }
         case value_t::number_integer:
@@ -6132,7 +6143,11 @@ inline void from_json(const BasicJsonType& j, ArithmeticType& val)
     {
         case value_t::number_unsigned:
         {
-            val = static_cast<ArithmeticType>(*j.template get_ptr<const typename BasicJsonType::number_unsigned_t*>());
+            // never null: a basic_json whose number_unsigned_t is number_integer_t
+            // stores no number_unsigned values (#2573)
+            const auto* ptr = j.template get_ptr<const typename BasicJsonType::number_unsigned_t*>();
+            JSON_ASSERT(ptr != nullptr);
+            val = static_cast<ArithmeticType>(*ptr);
             break;
         }
         case value_t::number_integer:
@@ -28916,7 +28931,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
         /// constructor for numbers (integer)
         json_value(number_integer_t v) noexcept : number_integer(v) {}
         /// constructor for numbers (unsigned); takes a placeholder if number_unsigned_t is number_integer_t
-        json_value(detail::number_unsigned_overload_t<basic_json> v) noexcept : number_unsigned(v) {}
+        json_value(detail::number_unsigned_overload_type<NumberIntegerType, NumberUnsignedType> v) noexcept : number_unsigned(v) {}
         /// constructor for numbers (floating-point)
         json_value(number_float_t v) noexcept : number_float(v) {}
         /// constructor for empty values of a given type
@@ -31189,14 +31204,14 @@ public:
 
     /// get a pointer to the value (unsigned number); takes a placeholder if
     /// number_unsigned_t is number_integer_t (the integer overload handles it then)
-    number_unsigned_t* get_impl_ptr(detail::number_unsigned_overload_t<basic_json>* /*unused*/) noexcept
+    number_unsigned_t* get_impl_ptr(detail::number_unsigned_overload_type<NumberIntegerType, NumberUnsignedType>* /*unused*/) noexcept
     {
         return is_number_unsigned() ? &m_data.m_value.number_unsigned : nullptr;
     }
 
     /// get a pointer to the value (unsigned number); takes a placeholder if
     /// number_unsigned_t is number_integer_t (the integer overload handles it then)
-    constexpr const number_unsigned_t* get_impl_ptr(const detail::number_unsigned_overload_t<basic_json>* /*unused*/) const noexcept
+    constexpr const number_unsigned_t* get_impl_ptr(const detail::number_unsigned_overload_type<NumberIntegerType, NumberUnsignedType>* /*unused*/) const noexcept
     {
         return is_number_unsigned() ? &m_data.m_value.number_unsigned : nullptr;
     }

tests/src/unit-same-number-types.cpp

@@ -157,10 +157,7 @@ TEST_CASE_TEMPLATE("same type for number_integer_t and number_unsigned_t", Json,
     {
         const Json source = Json::parse(R"({"a": [1, 2, 3], "b": 4})");
         const Json target = Json::parse(R"({"a": [1, 5], "c": 6})");
-        // GCC 5 crashes with an internal compiler error when instantiating patch_inplace for this type
-#if !defined(__GNUC__) || defined(__clang__) || __GNUC__ >= 6
         CHECK(source.patch(Json::diff(source, target)) == target);
-#endif
         CHECK(source.flatten().unflatten() == source);
     }