Merge branch 'develop' into claude/issue-5066-24ba30

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

include/nlohmann/detail/conversions/from_json.hpp

@@ -564,7 +564,7 @@ inline void from_json(const BasicJsonType& j, std::map<Key, Value, Compare, Allo
     {
         if (JSON_HEDLEY_UNLIKELY(!p.is_array()))
         {
-            JSON_THROW(type_error::create(302, concat("type must be array, but is ", p.type_name()), &p));
+            JSON_THROW(type_error::create(302, concat("type must be array, but is ", p.type_name()), &j));
         }
         m.emplace(p.at(0).template get<Key>(), p.at(1).template get<Value>());
     }
@@ -584,7 +584,7 @@ inline void from_json(const BasicJsonType& j, std::unordered_map<Key, Value, Has
     {
         if (JSON_HEDLEY_UNLIKELY(!p.is_array()))
         {
-            JSON_THROW(type_error::create(302, concat("type must be array, but is ", p.type_name()), &p));
+            JSON_THROW(type_error::create(302, concat("type must be array, but is ", p.type_name()), &j));
         }
         m.emplace(p.at(0).template get<Key>(), p.at(1).template get<Value>());
     }

single_include/nlohmann/json.hpp

@@ -6061,7 +6061,7 @@ inline void from_json(const BasicJsonType& j, std::map<Key, Value, Compare, Allo
     {
         if (JSON_HEDLEY_UNLIKELY(!p.is_array()))
         {
-            JSON_THROW(type_error::create(302, concat("type must be array, but is ", p.type_name()), &p));
+            JSON_THROW(type_error::create(302, concat("type must be array, but is ", p.type_name()), &j));
         }
         m.emplace(p.at(0).template get<Key>(), p.at(1).template get<Value>());
     }
@@ -6081,7 +6081,7 @@ inline void from_json(const BasicJsonType& j, std::unordered_map<Key, Value, Has
     {
         if (JSON_HEDLEY_UNLIKELY(!p.is_array()))
         {
-            JSON_THROW(type_error::create(302, concat("type must be array, but is ", p.type_name()), &p));
+            JSON_THROW(type_error::create(302, concat("type must be array, but is ", p.type_name()), &j));
         }
         m.emplace(p.at(0).template get<Key>(), p.at(1).template get<Value>());
     }

tests/src/unit-diagnostics.cpp

@@ -17,9 +17,6 @@
 #include <nlohmann/json.hpp>
 using nlohmann::json;
 
-#include <map>
-#include <unordered_map>
-
 TEST_CASE("Better diagnostics")
 {
     SECTION("empty JSON Pointer")
@@ -334,28 +331,6 @@ TEST_CASE("Regression tests for extended diagnostics")
         }
     }
 
-    SECTION("Regression test for issue #5668 - wrong path for std::map/unordered_map with non-string keys")
-    {
-        // a map with non-string keys is read from an array of [key, value] arrays;
-        // element 2 of "m" is not an array, so the path must point at "m/2", not "m"
-        json j;
-        j["outer"]["m"] = json::array({json::array({1, 2}), json::array({3, 4}), 5});
-
-        SECTION("std::map")
-        {
-            CHECK_THROWS_WITH_AS((j["outer"]["m"].get<std::map<int, int>>()),
-                                 "[json.exception.type_error.302] (/outer/m/2) type must be array, "
-                                 "but is number", json::type_error);
-        }
-
-        SECTION("std::unordered_map")
-        {
-            CHECK_THROWS_WITH_AS((j["outer"]["m"].get<std::unordered_map<int, int>>()),
-                                 "[json.exception.type_error.302] (/outer/m/2) type must be array, "
-                                 "but is number", json::type_error);
-        }
-    }
-
     SECTION("Regression test - swap(array_t&)/swap(object_t&) must update JSON_DIAGNOSTICS parent pointers")
     {
         // swap(array_t&)

tests/src/unit-regression2.cpp

@@ -766,6 +766,25 @@ TEST_CASE("regression tests 2")
         CHECK(j == k);
     }
 
+#ifdef JSON_HAS_CPP_17
+    SECTION("issue #5066 - MSVC converts json to std::variant<json> via the conversion operator")
+    {
+        // std::variant<json> must not be retrievable via get<>(), because otherwise the
+        // implicit conversion operator becomes a candidate that MSVC picks over the variant's
+        // converting constructor, routing a number through the string from_json overload
+        static_assert(!nlohmann::detail::is_detected<nlohmann::detail::get_template_function, const json&, std::variant<json>>::value,
+                      "std::variant<json> must not be retrievable via get<>()");
+
+        // clang before 7 cannot instantiate libstdc++'s std::variant<json>
+#if !(defined(__clang__) && __clang_major__ < 7)
+        // push_back, not emplace_back: #5066 needs the implicit conversion
+        // from json to the vector's value type
+        std::vector<std::variant<json>> v;
+        v.push_back(json(1)); // NOLINT(hicpp-use-emplace,modernize-use-emplace)
+        CHECK(std::get<0>(v[0]) == 1);
+#endif
+    }
+#endif
 }
 
 TEST_CASE("regression test - parser callback must not lose a duplicate key's prior value")