commit 20b5f4d89c163167cd0ab5c9340fc31b18a1b9cb
author Niels Lohmann <niels.lohmann@gmail.com> Mon Feb 12 18:17:59 2018 +0100
committer GitHub <noreply@github.com> Mon Feb 12 18:17:59 2018 +0100
tree 26ab21379356d9670ac4cf790175e9333b1b12cc
parent b02e3bb0b6397b5e5f2c92b163c8fa25c414c635
parent 01d611882884c8cd94b576342b1f7733f397c5b3

Merge pull request #969 from theodelrieu/fix/924

Fix constraints on from_json(CompatibleArrayType)

include/nlohmann/detail/conversions/from_json.hpp

diff --git a/include/nlohmann/detail/conversions/from_json.hpp b/include/nlohmann/detail/conversions/from_json.hpp
index 8ea0284..eccc04f 100644
--- a/include/nlohmann/detail/conversions/from_json.hpp
+++ b/include/nlohmann/detail/conversions/from_json.hpp
@@ -177,15 +177,21 @@
     }
 }
 
-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
-                     not std::is_same<typename BasicJsonType::array_t, CompatibleArrayType>::value, int> = 0>
+template <
+    typename BasicJsonType, typename CompatibleArrayType,
+    enable_if_t <
+        is_compatible_array_type<BasicJsonType, CompatibleArrayType>::value and
+        not std::is_same<typename BasicJsonType::array_t,
+                         CompatibleArrayType>::value and
+        std::is_constructible <
+            BasicJsonType, typename CompatibleArrayType::value_type >::value,
+        int > = 0 >
 void from_json(const BasicJsonType& j, CompatibleArrayType& arr)
 {
     if (JSON_UNLIKELY(not j.is_array()))
     {
-        JSON_THROW(type_error::create(302, "type must be array, but is " + std::string(j.type_name())));
+        JSON_THROW(type_error::create(302, "type must be array, but is " +
+                                      std::string(j.type_name())));
     }
 
     from_json_array_impl(j, arr, priority_tag<2> {});

single_include/nlohmann/json.hpp

diff --git a/single_include/nlohmann/json.hpp b/single_include/nlohmann/json.hpp
index a7c009c..c753058 100644
--- a/single_include/nlohmann/json.hpp
+++ b/single_include/nlohmann/json.hpp
@@ -1084,15 +1084,21 @@
     }
 }
 
-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
-                     not std::is_same<typename BasicJsonType::array_t, CompatibleArrayType>::value, int> = 0>
+template <
+    typename BasicJsonType, typename CompatibleArrayType,
+    enable_if_t <
+        is_compatible_array_type<BasicJsonType, CompatibleArrayType>::value and
+        not std::is_same<typename BasicJsonType::array_t,
+                         CompatibleArrayType>::value and
+        std::is_constructible <
+            BasicJsonType, typename CompatibleArrayType::value_type >::value,
+        int > = 0 >
 void from_json(const BasicJsonType& j, CompatibleArrayType& arr)
 {
     if (JSON_UNLIKELY(not j.is_array()))
     {
-        JSON_THROW(type_error::create(302, "type must be array, but is " + std::string(j.type_name())));
+        JSON_THROW(type_error::create(302, "type must be array, but is " +
+                                      std::string(j.type_name())));
     }
 
     from_json_array_impl(j, arr, priority_tag<2> {});

test/src/unit-inspection.cpp

diff --git a/test/src/unit-inspection.cpp b/test/src/unit-inspection.cpp
index 5facb11..4bee80d 100644
--- a/test/src/unit-inspection.cpp
+++ b/test/src/unit-inspection.cpp
@@ -316,8 +316,8 @@
     SECTION("round trips")
     {
         for (const auto& s :
-                {"3.141592653589793", "1000000000000000010E5"
-                })
+    {"3.141592653589793", "1000000000000000010E5"
+    })
         {
             json j1 = json::parse(s);
             std::string s1 = j1.dump();

test/src/unit-udt.cpp

diff --git a/test/src/unit-udt.cpp b/test/src/unit-udt.cpp
index 17baf4e..65ca788 100644
--- a/test/src/unit-udt.cpp
+++ b/test/src/unit-udt.cpp
@@ -711,3 +711,25 @@
 {
     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>>();
+}