From 1deeb434c679e7908875ce4ce0ce4583071ecc74 Mon Sep 17 00:00:00 2001
From: Florian Albrechtskirchinger <falbrechtskirchinger@gmail.com>
Date: Tue, 12 Apr 2022 14:08:20 +0200
Subject: [PATCH] Exclude std::any from implicit conversion (fixes #3428)
 (#3437)

* Exclude std::any from implicit conversion

Fixes #3428 (MSVC) and silences compiler warning on GCC (-Wconversion).

* Exclude std::any from implicit conversion
---
 include/nlohmann/json.hpp        |  4 ++++
 single_include/nlohmann/json.hpp |  4 ++++
 test/src/unit-regression2.cpp    | 13 +++++++++++++
 3 files changed, 21 insertions(+)

diff --git a/include/nlohmann/json.hpp b/include/nlohmann/json.hpp
index db85f8d7c1..b776708031 100644
--- a/include/nlohmann/json.hpp
+++ b/include/nlohmann/json.hpp
@@ -94,6 +94,7 @@ SOFTWARE.
 #include <nlohmann/ordered_map.hpp>
 
 #if defined(JSON_HAS_CPP_17)
+    #include <any>
     #include <string_view>
 #endif
 
@@ -1891,6 +1892,9 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
 
 #if defined(JSON_HAS_CPP_17) && (defined(__GNUC__) || (defined(_MSC_VER) && _MSC_VER >= 1910 && _MSC_VER <= 1914))
                                                 detail::negation<std::is_same<ValueType, std::string_view>>,
+#endif
+#if defined(JSON_HAS_CPP_17)
+                                                detail::negation<std::is_same<ValueType, std::any>>,
 #endif
                                                 detail::is_detected_lazy<detail::get_template_function, const basic_json_t&, ValueType>
                                                 >::value, int >::type = 0 >
diff --git a/single_include/nlohmann/json.hpp b/single_include/nlohmann/json.hpp
index c1f545b071..53c15b651e 100644
--- a/single_include/nlohmann/json.hpp
+++ b/single_include/nlohmann/json.hpp
@@ -17287,6 +17287,7 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
 
 
 #if defined(JSON_HAS_CPP_17)
+    #include <any>
     #include <string_view>
 #endif
 
@@ -19084,6 +19085,9 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
 
 #if defined(JSON_HAS_CPP_17) && (defined(__GNUC__) || (defined(_MSC_VER) && _MSC_VER >= 1910 && _MSC_VER <= 1914))
                                                 detail::negation<std::is_same<ValueType, std::string_view>>,
+#endif
+#if defined(JSON_HAS_CPP_17)
+                                                detail::negation<std::is_same<ValueType, std::any>>,
 #endif
                                                 detail::is_detected_lazy<detail::get_template_function, const basic_json_t&, ValueType>
                                                 >::value, int >::type = 0 >
diff --git a/test/src/unit-regression2.cpp b/test/src/unit-regression2.cpp
index 55bbcac654..feb800e76e 100644
--- a/test/src/unit-regression2.cpp
+++ b/test/src/unit-regression2.cpp
@@ -43,6 +43,7 @@ using ordered_json = nlohmann::ordered_json;
 #include <utility>
 
 #ifdef JSON_HAS_CPP_17
+    #include <any>
     #include <variant>
 #endif
 
@@ -860,6 +861,18 @@ TEST_CASE("regression tests 2")
         CHECK(obj.name == "class");
     }
 #endif
+
+#if defined(JSON_HAS_CPP_17) && JSON_USE_IMPLICIT_CONVERSIONS
+    SECTION("issue #3428 - Error occurred when converting nlohmann::json to std::any")
+    {
+        json j;
+        std::any a1 = j;
+        std::any&& a2 = j;
+
+        CHECK(a1.type() == typeid(j));
+        CHECK(a2.type() == typeid(j));
+    }
+#endif
 }
 
 DOCTEST_CLANG_SUPPRESS_WARNING_POP