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https://github.com/nlohmann/json.git
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Niels Lohmann
3b6ae43c53
* Add JSON_DISABLE_TUPLE_REFERENCE_CONVERSION to fix std::tuple conversions basic_json can be constructed from std::tuple<json&>, which it turns into a one-element array. Because of this, std::tuple picks its converting constructor that converts the whole source tuple instead of the element-wise one. As a result, std::tuple<const json&> built from std::forward_as_tuple(j) binds to a temporary (a compile error with libc++, a dangling reference with other standard libraries), and std::tuple<json> built the same way holds [j] instead of a copy of j. The new opt-in macro JSON_DISABLE_TUPLE_REFERENCE_CONVERSION (CMake option JSON_DisableTupleReferenceConversion) removes the conversion from a one-element tuple holding a reference to the same basic_json type, so std::tuple converts element-wise. It is off by default, so existing behavior is unchanged. It does not change any function body and therefore is not part of the ABI tag. Fixes #2226 Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Convert one-element tuples to arrays on every compiler to_json for std::tuple assigns a braced list, j = { std::get<Idx>(t)... }. With a single element that is itself a basic_json, Apple clang 15 and 16 treat j = {x} as a copy of x, so std::tuple<json>{true} became true instead of [true]. The macOS jobs (Xcode 15.1, 16.1) failed the new checks in unit-disable-tuple-reference-conversion and unit-regression2. The one-element overload that already handles JSON_BRACE_INIT_COPY_SEMANTICS builds the array (or object, for a [string, value] element) explicitly, the same way the initializer-list constructor does. Use it unconditionally. The output is unchanged on compilers that already wrapped the element. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Skip json reference tuple tests on clang < 4 and GCC < 5 ci_test_compilers_gcc_old (4.8) and ci_test_compilers_clang (3.4) could not compile the new tuple tests. Creating a std::tuple of basic_json references, e.g. std::forward_as_tuple(j), makes these compilers instantiate basic_json's conversion operator for libstdc++'s internal tuple bases, which fails hard. This happens with and without JSON_DISABLE_TUPLE_REFERENCE_CONVERSION, so it is a limitation of these compilers, not of the new option. Tested with the CI images: clang 3.4 to 3.9 and GCC 4.8 and 4.9 fail, clang 4, 5, and 6 and GCC 5 and 6 compile all cases. Skip only the checks that create such tuples; the is_constructible checks still run. Signed-off-by: Niels Lohmann <mail@nlohmann.me> --------- Signed-off-by: Niels Lohmann <mail@nlohmann.me>
52 lines
1.4 KiB
C++
52 lines
1.4 KiB
C++
// __ _____ _____ _____
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// __| | __| | | | JSON for Modern C++
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// | | |__ | | | | | | version 3.12.0
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// |_____|_____|_____|_|___| https://github.com/nlohmann/json
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//
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// SPDX-FileCopyrightText: 2013-2026 Niels Lohmann <https://nlohmann.me>
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// SPDX-License-Identifier: MIT
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#pragma once
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// restore clang diagnostic settings
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#if defined(__clang__)
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#pragma clang diagnostic pop
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#endif
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// clean up
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#undef JSON_ASSERT
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#undef JSON_INTERNAL_CATCH
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#undef JSON_THROW
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#undef JSON_PRIVATE_UNLESS_TESTED
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#undef NLOHMANN_BASIC_JSON_TPL_DECLARATION
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#undef NLOHMANN_BASIC_JSON_TPL
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#undef JSON_EXPLICIT
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#undef NLOHMANN_CAN_CALL_STD_FUNC_IMPL
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#undef JSON_INLINE_VARIABLE
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#undef JSON_NO_UNIQUE_ADDRESS
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#undef JSON_DISABLE_ENUM_SERIALIZATION
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#undef JSON_DISABLE_TUPLE_REFERENCE_CONVERSION
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#ifndef JSON_TEST_KEEP_MACROS
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#undef JSON_CATCH
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#undef JSON_TRY
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#undef JSON_HAS_CPP_11
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#undef JSON_HAS_CPP_14
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#undef JSON_HAS_CPP_17
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#undef JSON_HAS_CPP_20
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#undef JSON_HAS_CPP_23
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#undef JSON_HAS_CPP_26
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#undef JSON_HAS_FILESYSTEM
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#undef JSON_HAS_EXPERIMENTAL_FILESYSTEM
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#undef JSON_HAS_THREE_WAY_COMPARISON
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#undef JSON_HAS_RANGES
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#undef JSON_HAS_STD_FORMAT
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#undef JSON_HAS_STATIC_RTTI
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#undef JSON_USE_LEGACY_DISCARDED_VALUE_COMPARISON
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#undef JSON_BRACE_INIT_COPY_SEMANTICS
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#undef JSON_PRECISE_STREAM_POSITION
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#undef JSON_STRICT_NUL_HANDLING
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#endif
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#include <nlohmann/thirdparty/hedley/hedley_undef.hpp>
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