Remove unused would_call_std_* from NLOHMANN_CAN_CALL_STD_FUNC_IMPL

Besides detail::result_of_begin/end, which is_range and iterator_t use,
the macro defined a namespace detail2 with a tag type, a catch-all
overload and would_call_std_begin/end, plus would_call_std_begin/end
structs directly in namespace nlohmann. Nothing has used them since
they were added in #3020.

Reduce the macro to its detail part. Without the trailing struct the
';' after the two invocations would be an empty declaration that
-Wextra-semi flags, so drop it. macro_scope.hpp included
meta/detected.hpp only for this macro; all users of detected.hpp
include it (or type_traits.hpp) themselves, so remove the include.

Behavior and ABI are unchanged. The undocumented, untested and unused
names nlohmann::would_call_std_begin, nlohmann::would_call_std_end and
namespace nlohmann::detail2 are no longer declared.

Part of #5708

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
This commit is contained in:
Niels Lohmann
2026-09-30 09:46:04 +02:00
parent 31883d06a8
commit f9d4b51455
4 changed files with 96 additions and 147 deletions
-25
View File
@@ -9,7 +9,6 @@
#pragma once
#include <utility> // declval, pair
#include <nlohmann/detail/meta/detected.hpp>
#include <nlohmann/thirdparty/hedley/hedley.hpp>
// This file contains all internal macro definitions (except those affecting ABI)
@@ -876,30 +875,6 @@ void templated_json_throw(ExceptionType exception)
\
template<typename... T> \
using result_of_##std_name = decltype(std_name(std::declval<T>()...)); \
} \
\
namespace detail2 { \
struct std_name##_tag \
{ \
}; \
\
template<typename... T> \
std_name##_tag std_name(T&&...); \
\
template<typename... T> \
using result_of_##std_name = decltype(std_name(std::declval<T>()...)); \
\
template<typename... T> \
struct would_call_std_##std_name \
{ \
static constexpr auto const value = ::nlohmann::detail:: \
is_detected_exact<std_name##_tag, result_of_##std_name, T...>::value; \
}; \
} /* namespace detail2 */ \
\
template<typename... T> \
struct would_call_std_##std_name : detail2::would_call_std_##std_name<T...> \
{ \
}
#ifndef JSON_USE_IMPLICIT_CONVERSIONS
@@ -12,6 +12,6 @@
NLOHMANN_JSON_NAMESPACE_BEGIN
NLOHMANN_CAN_CALL_STD_FUNC_IMPL(begin);
NLOHMANN_CAN_CALL_STD_FUNC_IMPL(begin)
NLOHMANN_JSON_NAMESPACE_END
@@ -12,6 +12,6 @@
NLOHMANN_JSON_NAMESPACE_BEGIN
NLOHMANN_CAN_CALL_STD_FUNC_IMPL(end);
NLOHMANN_CAN_CALL_STD_FUNC_IMPL(end)
NLOHMANN_JSON_NAMESPACE_END
+94 -120
View File
@@ -275,100 +275,6 @@
#include <utility> // declval, pair
// #include <nlohmann/detail/meta/detected.hpp>
// __ _____ _____ _____
// __| | __| | | | JSON for Modern C++
// | | |__ | | | | | | version 3.12.0
// |_____|_____|_____|_|___| https://github.com/nlohmann/json
//
// SPDX-FileCopyrightText: 2013-2026 Niels Lohmann <https://nlohmann.me>
// SPDX-License-Identifier: MIT
#include <type_traits>
// #include <nlohmann/detail/meta/void_t.hpp>
// __ _____ _____ _____
// __| | __| | | | JSON for Modern C++
// | | |__ | | | | | | version 3.12.0
// |_____|_____|_____|_|___| https://github.com/nlohmann/json
//
// SPDX-FileCopyrightText: 2013-2026 Niels Lohmann <https://nlohmann.me>
// SPDX-License-Identifier: MIT
// #include <nlohmann/detail/abi_macros.hpp>
NLOHMANN_JSON_NAMESPACE_BEGIN
namespace detail
{
template<typename ...Ts> struct make_void
{
using type = void;
};
template<typename ...Ts> using void_t = typename make_void<Ts...>::type;
} // namespace detail
NLOHMANN_JSON_NAMESPACE_END
NLOHMANN_JSON_NAMESPACE_BEGIN
namespace detail
{
// https://en.cppreference.com/w/cpp/experimental/is_detected
struct nonesuch
{
nonesuch() = delete;
~nonesuch() = delete;
nonesuch(nonesuch const&) = delete;
nonesuch(nonesuch const&&) = delete;
void operator=(nonesuch const&) = delete;
void operator=(nonesuch&&) = delete;
};
template<class Default,
class AlwaysVoid,
template<class...> class Op,
class... Args>
struct detector
{
using value_t = std::false_type;
using type = Default;
};
template<class Default, template<class...> class Op, class... Args>
struct detector<Default, void_t<Op<Args...>>, Op, Args...>
{
using value_t = std::true_type;
using type = Op<Args...>;
};
template<template<class...> class Op, class... Args>
using is_detected = typename detector<nonesuch, void, Op, Args...>::value_t;
template<template<class...> class Op, class... Args>
struct is_detected_lazy : is_detected<Op, Args...> { };
template<template<class...> class Op, class... Args>
using detected_t = typename detector<nonesuch, void, Op, Args...>::type;
template<class Default, template<class...> class Op, class... Args>
using detected_or = detector<Default, void, Op, Args...>;
template<class Default, template<class...> class Op, class... Args>
using detected_or_t = typename detected_or<Default, Op, Args...>::type;
template<class Expected, template<class...> class Op, class... Args>
using is_detected_exact = std::is_same<Expected, detected_t<Op, Args...>>;
} // namespace detail
NLOHMANN_JSON_NAMESPACE_END
// #include <nlohmann/thirdparty/hedley/hedley.hpp>
@@ -3283,30 +3189,6 @@ void templated_json_throw(ExceptionType exception)
\
template<typename... T> \
using result_of_##std_name = decltype(std_name(std::declval<T>()...)); \
} \
\
namespace detail2 { \
struct std_name##_tag \
{ \
}; \
\
template<typename... T> \
std_name##_tag std_name(T&&...); \
\
template<typename... T> \
using result_of_##std_name = decltype(std_name(std::declval<T>()...)); \
\
template<typename... T> \
struct would_call_std_##std_name \
{ \
static constexpr auto const value = ::nlohmann::detail:: \
is_detected_exact<std_name##_tag, result_of_##std_name, T...>::value; \
}; \
} /* namespace detail2 */ \
\
template<typename... T> \
struct would_call_std_##std_name : detail2::would_call_std_##std_name<T...> \
{ \
}
#ifndef JSON_USE_IMPLICIT_CONVERSIONS
@@ -3856,6 +3738,31 @@ NLOHMANN_JSON_NAMESPACE_END
// #include <nlohmann/detail/abi_macros.hpp>
// #include <nlohmann/detail/meta/void_t.hpp>
// __ _____ _____ _____
// __| | __| | | | JSON for Modern C++
// | | |__ | | | | | | version 3.12.0
// |_____|_____|_____|_|___| https://github.com/nlohmann/json
//
// SPDX-FileCopyrightText: 2013-2026 Niels Lohmann <https://nlohmann.me>
// SPDX-License-Identifier: MIT
// #include <nlohmann/detail/abi_macros.hpp>
NLOHMANN_JSON_NAMESPACE_BEGIN
namespace detail
{
template<typename ...Ts> struct make_void
{
using type = void;
};
template<typename ...Ts> using void_t = typename make_void<Ts...>::type;
} // namespace detail
NLOHMANN_JSON_NAMESPACE_END
// #include <nlohmann/detail/meta/cpp_future.hpp>
@@ -3927,7 +3834,7 @@ NLOHMANN_JSON_NAMESPACE_END
NLOHMANN_JSON_NAMESPACE_BEGIN
NLOHMANN_CAN_CALL_STD_FUNC_IMPL(begin);
NLOHMANN_CAN_CALL_STD_FUNC_IMPL(begin)
NLOHMANN_JSON_NAMESPACE_END
@@ -3947,13 +3854,80 @@ NLOHMANN_JSON_NAMESPACE_END
NLOHMANN_JSON_NAMESPACE_BEGIN
NLOHMANN_CAN_CALL_STD_FUNC_IMPL(end);
NLOHMANN_CAN_CALL_STD_FUNC_IMPL(end)
NLOHMANN_JSON_NAMESPACE_END
// #include <nlohmann/detail/meta/cpp_future.hpp>
// #include <nlohmann/detail/meta/detected.hpp>
// __ _____ _____ _____
// __| | __| | | | JSON for Modern C++
// | | |__ | | | | | | version 3.12.0
// |_____|_____|_____|_|___| https://github.com/nlohmann/json
//
// SPDX-FileCopyrightText: 2013-2026 Niels Lohmann <https://nlohmann.me>
// SPDX-License-Identifier: MIT
#include <type_traits>
// #include <nlohmann/detail/meta/void_t.hpp>
NLOHMANN_JSON_NAMESPACE_BEGIN
namespace detail
{
// https://en.cppreference.com/w/cpp/experimental/is_detected
struct nonesuch
{
nonesuch() = delete;
~nonesuch() = delete;
nonesuch(nonesuch const&) = delete;
nonesuch(nonesuch const&&) = delete;
void operator=(nonesuch const&) = delete;
void operator=(nonesuch&&) = delete;
};
template<class Default,
class AlwaysVoid,
template<class...> class Op,
class... Args>
struct detector
{
using value_t = std::false_type;
using type = Default;
};
template<class Default, template<class...> class Op, class... Args>
struct detector<Default, void_t<Op<Args...>>, Op, Args...>
{
using value_t = std::true_type;
using type = Op<Args...>;
};
template<template<class...> class Op, class... Args>
using is_detected = typename detector<nonesuch, void, Op, Args...>::value_t;
template<template<class...> class Op, class... Args>
struct is_detected_lazy : is_detected<Op, Args...> { };
template<template<class...> class Op, class... Args>
using detected_t = typename detector<nonesuch, void, Op, Args...>::type;
template<class Default, template<class...> class Op, class... Args>
using detected_or = detector<Default, void, Op, Args...>;
template<class Default, template<class...> class Op, class... Args>
using detected_or_t = typename detected_or<Default, Op, Args...>::type;
template<class Expected, template<class...> class Op, class... Args>
using is_detected_exact = std::is_same<Expected, detected_t<Op, Args...>>;
} // namespace detail
NLOHMANN_JSON_NAMESPACE_END
// #include <nlohmann/json_fwd.hpp>
// __ _____ _____ _____