From 9a35702da80b78ef1c157434a68f1d17a94328ba Mon Sep 17 00:00:00 2001
From: Niels Lohmann <mail@nlohmann.me>
Date: Wed, 13 Oct 2021 20:34:17 +0200
Subject: [PATCH] :rewind: remove "fix" that caused #3077

---
 include/nlohmann/json.hpp        |  2 +-
 single_include/nlohmann/json.hpp |  2 +-
 test/src/unit-regression2.cpp    | 34 ++++++++++++++++++++++++++++++++
 3 files changed, 36 insertions(+), 2 deletions(-)

diff --git a/include/nlohmann/json.hpp b/include/nlohmann/json.hpp
index b140577f2c..19c6011835 100644
--- a/include/nlohmann/json.hpp
+++ b/include/nlohmann/json.hpp
@@ -3069,7 +3069,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     ValueType get_impl(detail::priority_tag<0> /*unused*/) const noexcept(noexcept(
                 JSONSerializer<ValueType>::from_json(std::declval<const basic_json_t&>(), std::declval<ValueType&>())))
     {
-        ValueType ret{};
+        ValueType ret;
         JSONSerializer<ValueType>::from_json(*this, ret);
         return ret;
     }
diff --git a/single_include/nlohmann/json.hpp b/single_include/nlohmann/json.hpp
index 25c6983b04..e41ff9ec94 100644
--- a/single_include/nlohmann/json.hpp
+++ b/single_include/nlohmann/json.hpp
@@ -20556,7 +20556,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     ValueType get_impl(detail::priority_tag<0> /*unused*/) const noexcept(noexcept(
                 JSONSerializer<ValueType>::from_json(std::declval<const basic_json_t&>(), std::declval<ValueType&>())))
     {
-        ValueType ret{};
+        ValueType ret;
         JSONSerializer<ValueType>::from_json(*this, ret);
         return ret;
     }
diff --git a/test/src/unit-regression2.cpp b/test/src/unit-regression2.cpp
index cf74297825..e84b8bd81e 100644
--- a/test/src/unit-regression2.cpp
+++ b/test/src/unit-regression2.cpp
@@ -189,6 +189,32 @@ template<class T>
 class my_allocator : public std::allocator<T>
 {};
 
+/////////////////////////////////////////////////////////////////////
+// for #3077
+/////////////////////////////////////////////////////////////////////
+
+class FooAlloc
+{};
+
+class Foo
+{
+  public:
+    explicit Foo(const FooAlloc& = FooAlloc()) : value(false) {}
+
+    bool value;
+};
+
+class FooBar
+{
+  public:
+    Foo foo;
+};
+
+inline void from_json(const nlohmann::json& j, FooBar& fb)
+{
+    j.at("value").get_to(fb.foo.value);
+}
+
 TEST_CASE("regression tests 2")
 {
     SECTION("issue #1001 - Fix memory leak during parser callback")
@@ -695,6 +721,14 @@ TEST_CASE("regression tests 2")
         json k = json::from_cbor(my_vector);
         CHECK(j == k);
     }
+
+    SECTION("issue #3077 - explicit constructor with default does not compile")
+    {
+        json j;
+        j[0]["value"] = true;
+        std::vector<FooBar> foo;
+        j.get_to(foo);
+    }
 }
 
 DOCTEST_CLANG_SUPPRESS_WARNING_POP