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Niels Lohmann
b8d53c0888
tests/src/unit-no-macro-leak.cpp previously hardcoded a static list of ~151 #ifdef/#error checks, one per JSON_HEDLEY_* macro name known at the time it was written. That list would silently go stale the next time `make update_hedley` pulls in a vendor update that adds, removes, or renames a macro, since nothing would force it to be regenerated. Add cmake/scripts/gen_hedley_undef_check.cmake, which derives the full list of JSON_HEDLEY_* macro names directly from include/nlohmann/thirdparty/hedley/hedley.hpp: - tests/CMakeLists.txt uses it (MODE=checks) to (re)generate hedley_undef_checks.inc at configure and build time, and wires the generating custom target as a dependency of the test-no-macro-leak_cpp* targets so it can never build against a stale copy. unit-no-macro-leak.cpp now just #include-s the generated file inside its TEST_CASE instead of carrying the checks itself. - The Makefile's `update_hedley` target now delegates hedley_undef.hpp generation to the same script (MODE=undef, new `update_hedley_undef` target), so the vendored header, the generated #undef list, and the generated test checks are all derived from the same extraction logic and cannot drift apart. This mirrors the approach taken independently in #5415 for the same issue (#5408), credited there to a self-regenerating mechanism that "can never drift again" -- ported into this branch instead of the static list originally proposed here. Verified with a local CMake configure + build + ctest, both against include/ (JSON_MultipleHeaders=ON) and against the amalgamated single_include/nlohmann/json.hpp (JSON_MultipleHeaders=OFF), and by temporarily deleting a #undef line from hedley_undef.hpp to confirm the generated test actually fails on a real leak. Signed-off-by: Niels Lohmann <mail@nlohmann.me>
106 lines
4.4 KiB
CMake
106 lines
4.4 KiB
CMake
# Shared extractor for the JSON_HEDLEY_* macro names defined in hedley.hpp.
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#
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# Every macro that hedley.hpp #defines must be #undef-ed again once json.hpp
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# has been fully processed (see include/nlohmann/detail/macro_unscope.hpp
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# and https://github.com/nlohmann/json/issues/5408). Deriving the macro list
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# straight from hedley.hpp here -- instead of hand-maintaining it in two
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# places -- means hedley_undef.hpp and the regression test that checks for
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# leaked macros can never drift apart, even after a future `make
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# update_hedley` pulls in new macros from upstream Hedley.
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#
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# MODE=undef (default): write hedley_undef.hpp (SPDX header, #pragma once,
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# one #undef per macro name) -- used by `make update_hedley_undef`
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# MODE=checks: write one #ifdef/FAIL_CHECK/#endif per macro name,
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# meant to be #include-d inside a TEST_CASE -- used by
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# tests/CMakeLists.txt to (re)generate the include for
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# tests/src/unit-no-macro-leak.cpp
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#
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# Required variables:
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# HEDLEY_HPP path to include/nlohmann/thirdparty/hedley/hedley.hpp
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# OUTPUT path of the file to (over)write
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# Optional:
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# MODE "undef" (default) or "checks"
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if(NOT DEFINED HEDLEY_HPP OR NOT DEFINED OUTPUT)
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message(FATAL_ERROR "HEDLEY_HPP and OUTPUT must be set")
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endif()
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if(NOT EXISTS "${HEDLEY_HPP}")
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message(FATAL_ERROR "Hedley header not found: ${HEDLEY_HPP}")
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endif()
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if(NOT DEFINED MODE)
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set(MODE undef)
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endif()
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if(NOT MODE STREQUAL "undef" AND NOT MODE STREQUAL "checks")
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message(FATAL_ERROR "MODE must be undef or checks, got: ${MODE}")
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endif()
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# Line-anchored, like `grep -oE "^[[:blank:]]*#[[:blank:]]*define[[:blank:]]+JSON_HEDLEY_[A-Za-z0-9_]+"`.
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# Unanchored matching would also pick up JSON_HEDLEY_* mentions inside
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# comments or string literals elsewhere in the file, which must not turn
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# into #undef lines.
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file(STRINGS "${HEDLEY_HPP}" hedley_lines)
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set(macro_names)
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foreach(line IN LISTS hedley_lines)
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if("${line}" MATCHES "^[ \t]*#[ \t]*define[ \t]+(JSON_HEDLEY_[A-Za-z0-9_]+)")
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list(APPEND macro_names "${CMAKE_MATCH_1}")
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endif()
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endforeach()
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if(NOT macro_names)
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message(FATAL_ERROR "No JSON_HEDLEY_* macros found in ${HEDLEY_HPP}")
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endif()
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list(REMOVE_DUPLICATES macro_names)
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# Lexicographic, locale-independent (ASCII-only names) -- matches `LC_ALL=C sort`.
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list(SORT macro_names COMPARE STRING)
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list(LENGTH macro_names macro_count)
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set(generated "")
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if(MODE STREQUAL "undef")
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# Same banner `make update_hedley_undef` would stamp by hand, so the
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# recipe is self-contained and its output is byte-stable across reruns.
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string(APPEND generated "// __ _____ _____ _____\n")
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string(APPEND generated "// __| | __| | | | JSON for Modern C++\n")
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string(APPEND generated "// | | |__ | | | | | | version 3.12.0\n")
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string(APPEND generated "// |_____|_____|_____|_|___| https://github.com/nlohmann/json\n")
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string(APPEND generated "//\n")
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string(APPEND generated "// SPDX-FileCopyrightText: 2013-2026 Niels Lohmann <https://nlohmann.me>\n")
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string(APPEND generated "// SPDX-License-Identifier: MIT\n")
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string(APPEND generated "\n")
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string(APPEND generated "#pragma once\n")
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string(APPEND generated "\n")
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foreach(name IN LISTS macro_names)
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string(APPEND generated "#undef ${name}\n")
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endforeach()
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else()
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string(APPEND generated "// This file is generated by cmake/scripts/gen_hedley_undef_check.cmake\n")
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string(APPEND generated "// from include/nlohmann/thirdparty/hedley/hedley.hpp. Do not edit it by\n")
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string(APPEND generated "// hand -- it is regenerated on every build. ${macro_count} macros checked.\n\n")
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foreach(name IN LISTS macro_names)
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string(APPEND generated "#ifdef ${name}\n")
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string(APPEND generated " FAIL_CHECK(\"${name} leaked after including nlohmann/json.hpp\");\n")
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string(APPEND generated "#endif\n")
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endforeach()
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endif()
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get_filename_component(output_dir "${OUTPUT}" DIRECTORY)
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if(output_dir)
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file(MAKE_DIRECTORY "${output_dir}")
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endif()
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# Avoid rewriting the file (and busting downstream incremental rebuilds)
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# when the content has not actually changed.
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set(write_output TRUE)
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if(EXISTS "${OUTPUT}")
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file(READ "${OUTPUT}" existing_content)
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if(existing_content STREQUAL generated)
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set(write_output FALSE)
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endif()
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endif()
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if(write_output)
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file(WRITE "${OUTPUT}" "${generated}")
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endif()
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