Fix constraints on from_json(CompatibleArrayType)

Fixes #924
nlohmann · Feb 12, 2018 · 5a6cc0c · 5a6cc0c
1 parent 447f542
commit 5a6cc0c
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Showing 4 changed files with 26 additions and 4 deletions.
diff --git a/include/nlohmann/detail/conversions/from_json.hpp b/include/nlohmann/detail/conversions/from_json.hpp
@@ -179,7 +179,7 @@ void from_json_array_impl(const BasicJsonType& j, std::array<T, N>& arr, priorit
 
 template<typename BasicJsonType, typename CompatibleArrayType,
          enable_if_t<is_compatible_array_type<BasicJsonType, CompatibleArrayType>::value and
-                     std::is_convertible<BasicJsonType, typename CompatibleArrayType::value_type>::value and
+                     has_from_json<BasicJsonType, typename CompatibleArrayType::value_type>::value and
                      not std::is_same<typename BasicJsonType::array_t, CompatibleArrayType>::value, int> = 0>
 void from_json(const BasicJsonType& j, CompatibleArrayType& arr)
 {

diff --git a/single_include/nlohmann/json.hpp b/single_include/nlohmann/json.hpp
@@ -1086,7 +1086,7 @@ void from_json_array_impl(const BasicJsonType& j, std::array<T, N>& arr, priorit
 
 template<typename BasicJsonType, typename CompatibleArrayType,
          enable_if_t<is_compatible_array_type<BasicJsonType, CompatibleArrayType>::value and
-                     std::is_convertible<BasicJsonType, typename CompatibleArrayType::value_type>::value and
+                     has_from_json<BasicJsonType, typename CompatibleArrayType::value_type>::value and
                      not std::is_same<typename BasicJsonType::array_t, CompatibleArrayType>::value, int> = 0>
 void from_json(const BasicJsonType& j, CompatibleArrayType& arr)
 {

diff --git a/test/src/unit-inspection.cpp b/test/src/unit-inspection.cpp
@@ -316,8 +316,8 @@ TEST_CASE("object inspection")
     SECTION("round trips")
     {
         for (const auto& s :
-                {"3.141592653589793", "1000000000000000010E5"
-                })
+    {"3.141592653589793", "1000000000000000010E5"
+    })
         {
             json j1 = json::parse(s);
             std::string s1 = j1.dump();

diff --git a/test/src/unit-udt.cpp b/test/src/unit-udt.cpp
@@ -711,3 +711,25 @@ TEST_CASE("an incomplete type does not trigger a compiler error in non-evaluated
 {
     static_assert(not is_constructible_patched<json, incomplete>::value, "");
 }
+
+namespace
+{
+class Evil
+{
+  public:
+    Evil() = default;
+    template <typename T>
+    Evil(T) {}
+};
+
+void from_json(const json&, Evil&) {}
+}
+
+TEST_CASE("Issue #924")
+{
+    // Prevent get<std::vector<Evil>>() to throw
+    auto j = json::array();
+
+    (void) j.get<Evil>();
+    (void) j.get<std::vector<Evil>>();
+}