From 17d6fa753bdab3c8a5ecdaa42c257ac1beb53bfa Mon Sep 17 00:00:00 2001
From: Niels Lohmann <mail@nlohmann.me>
Date: Mon, 31 Aug 2026 09:24:25 +0000
Subject: [PATCH] Give the custom container types only the constructors the
 library uses

The three container types in the new tests inherited every constructor of
their base with using Base::Base. That asks for more than the test needs: the
library builds an object or an array by default construction, by copy or move,
and -- when converting between two basic_json types or from an initializer
list -- from an iterator range. Declaring those directly makes the requirement
visible in the test, and keeps object types out of a corner where a compiler
has to declare std::map's whole constructor set for a derived class while
basic_json is still incomplete.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
---
 tests/src/unit-custom-array-type.cpp  | 6 +++++-
 tests/src/unit-custom-object-type.cpp | 8 ++++++--
 2 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/tests/src/unit-custom-array-type.cpp b/tests/src/unit-custom-array-type.cpp
index df66340a1..00606c6e0 100644
--- a/tests/src/unit-custom-array-type.cpp
+++ b/tests/src/unit-custom-array-type.cpp
@@ -30,7 +30,11 @@ template<class T, class Allocator = std::allocator<T>>
 class vector_without_at : public std::vector<T, Allocator>
 {
   public:
-    using std::vector<T, Allocator>::vector;
+    vector_without_at() = default;
+
+    // the array of an initializer list is built from a range
+    template<class InputIt>
+    vector_without_at(InputIt first, InputIt last) : std::vector<T, Allocator>(first, last) {}
 
     void at() = delete;
 };
diff --git a/tests/src/unit-custom-object-type.cpp b/tests/src/unit-custom-object-type.cpp
index 79b2ac6cc..c27c5ea23 100644
--- a/tests/src/unit-custom-object-type.cpp
+++ b/tests/src/unit-custom-object-type.cpp
@@ -35,7 +35,12 @@ template<class Key, class T, class Compare, class Allocator>
 struct no_key_compare_map : std::map<Key, T, Compare, Allocator>
 {
     using base_t = std::map<Key, T, Compare, Allocator>;
-    using base_t::base_t;
+
+    no_key_compare_map() = default;
+
+    // converting between two basic_json types builds the object from a range
+    template<class InputIt>
+    no_key_compare_map(InputIt first, InputIt last) : base_t(first, last) {}
 
     // shadows base_t::key_compare, which is a type; never defined or called
     void key_compare();
@@ -49,7 +54,6 @@ template<class Key, class T, class Compare, class Allocator>
 struct void_erase_map : std::map<Key, T, Compare, Allocator>
 {
     using base_t = std::map<Key, T, Compare, Allocator>;
-    using base_t::base_t;
     using iterator = typename base_t::iterator;
     using base_t::erase;