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* Undefine the four JSON_HEDLEY_* macros that leak after including json.hpp include/nlohmann/detail/macro_unscope.hpp includes hedley_undef.hpp to #undef every JSON_HEDLEY_* macro so none of them leak into the including translation unit. Four macros were missing from that list and therefore stayed defined after #include <nlohmann/json.hpp>: - JSON_HEDLEY_PRAGMA - JSON_HEDLEY_PREDICT_TRUE - JSON_HEDLEY_PREDICT_FALSE - JSON_HEDLEY_CLANG_HAS_DECLSPEC_ATTRIBUTE hedley_undef.hpp is generated (via `make update_hedley`) by grepping hedley.hpp for its own internal `#undef JSON_HEDLEY_X` redefinition guards. JSON_HEDLEY_PRAGMA/PREDICT_TRUE/PREDICT_FALSE have no such guard in upstream Hedley, so they were never picked up. The guard for JSON_HEDLEY_CLANG_HAS_DECLSPEC_ATTRIBUTE also has an upstream typo (`JSON_HEDLEY_CLANG_HAS_DECLSPEC_DECLSPEC_ATTRIBUTE`), so hedley_undef.hpp was undefining the wrong (never-defined) name. Fixes: - include/nlohmann/thirdparty/hedley/hedley_undef.hpp: corrected the DECLSPEC_ATTRIBUTE typo and added the three missing #undef lines, keeping the file's alphabetical ordering. - Makefile (update_hedley target): changed hedley_undef.hpp generation to extract macro names directly from every `#define JSON_HEDLEY_...` in hedley.hpp instead of from existing `#undef` guards, so a future `make update_hedley` run undefines every macro Hedley actually defines, even ones without a pre-existing redefinition guard. This was not run in this PR (it would also pull in an unrelated upstream Hedley sync); hedley_undef.hpp was hand-patched instead and single_include was regenerated with `make amalgamate`. - tests/src/unit-no-macro-leak.cpp: new regression test (picked up automatically by tests/CMakeLists.txt's existing unit-*.cpp glob) that includes json.hpp and then #ifdef/#error-checks every JSON_HEDLEY_* macro name, so any future leak of any of the 151 vendored macros fails the build, not just the four fixed here. Fixes #5408. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Derive the JSON_HEDLEY_* leak-check test from hedley.hpp at build time 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> * Fix REUSE compliance failure in gen_hedley_undef_check.cmake The generated file's embedded banner contains the literal text 'SPDX-License-Identifier: MIT' as part of the *content* being written to hedley_undef.hpp, not as this .cmake script's own REUSE header (it is already covered by the blanket 'Files: *' rule in .reuse/dep5). The reuse tool matched that embedded line as an SPDX tag for the script itself and failed to parse the trailing 'MIT\n")' as a valid SPDX License Expression, breaking ci_reuse_compliance. Wrap the embedded banner in REUSE-IgnoreStart/REUSE-IgnoreEnd comments, as recommended by the tool's own diagnostic output. Signed-off-by: Niels Lohmann <mail@nlohmann.me> --------- Signed-off-by: Niels Lohmann <mail@nlohmann.me>