Replace meta/logic.hpp with a disjunction trait

meta/logic.hpp added a second set of type-level boolean helpers
(cxpr_and, cxpr_or, cxpr_not, ...) next to the existing conjunction
and negation in type_traits.hpp. It was used only by one static_assert
in from_json_tuple_impl, two of its templates were never used, and it
was the only header without the license banner and relied on
transitive includes for <type_traits>.

Add the missing disjunction next to conjunction and negation, use the
three in the static_assert, and delete logic.hpp together with its
BUILD.bazel entry. same_sign now uses disjunction as well, which
resolves the 2022 TODO waiting for such a trait.

The static_assert accepts and rejects the same types as before. Only
names in nlohmann::detail change; behavior, public API and ABI are
unchanged.

Part of #5708

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
This commit is contained in:
Niels Lohmann committed 2026-09-30 09:42:12 +02:00
1 parent 4c208728e7
commit 31883d06a8
5 files changed
+18 -121

No files matched your search

@@ -27,7 +27,6 @@
#include <nlohmann/detail/meta/identity_tag.hpp>
#include <nlohmann/detail/meta/std_fs.hpp>
#include <nlohmann/detail/meta/type_traits.hpp>
#include <nlohmann/detail/meta/logic.hpp>
#include <nlohmann/detail/string_concat.hpp>
#include <nlohmann/detail/value_t.hpp>
@@ -527,7 +526,7 @@ inline void from_json_tuple_impl(BasicJsonType&& j, std::pair<A1, A2>& p, priori
template<typename BasicJsonType, typename... Args>
std::tuple<Args...> from_json_tuple_impl(BasicJsonType&& j, identity_tag<std::tuple<Args...>> /*unused*/, priority_tag<2> /*unused*/)
{
static_assert(cxpr_and<cxpr_or<cxpr_not<std::is_reference<Args>>, is_compatible_reference_type<BasicJsonType, Args>>...>::value,
static_assert(conjunction<disjunction<negation<std::is_reference<Args>>, is_compatible_reference_type<BasicJsonType, Args>>...>::value,
"Can not return a tuple containing references to types not contained in a Json, try Json::get_to()");
return from_json_tuple_impl_base<1, Args...>(std::forward<BasicJsonType>(j), index_sequence_for<Args...> {});
}