Niels Lohmann ce210a3419 Keep user macros named EMPTY or MEMBERS out of the member-count dispatch ...

The dispatch produced the bare token EMPTY or MEMBERS and pasted it onto
the macro prefix afterwards. In between, the token was rescanned, so a
user macro with either name replaced it: with `#define MEMBERS x` in
scope, even NLOHMANN_DEFINE_TYPE_INTRUSIVE(A, member) -- which compiled
before -- expanded to garbage, and `#define EMPTY` broke the zero-member
form.

Paste the suffix onto the prefix directly in the GET_MACRO slot table
instead. Operands of ## are not macro-expanded, so the selected body name
is formed before any user macro can interfere. NLOHMANN_JSON_TYPE_TAG and
NLOHMANN_JSON_DERIVED_TYPE_TAG become NLOHMANN_JSON_TYPE_BODY and
NLOHMANN_JSON_DERIVED_TYPE_BODY, taking the prefix as their first
argument; NLOHMANN_JSON_CAT is no longer needed. The body macro names are
unchanged, and so is the generated code.

Add a regression test that defines EMPTY and MEMBERS around plain and
derived types, with and without members.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

2026-09-23 20:28:37 +02:00

..

json_fwd.hpp

📄 adjust year (#5044)

2026-01-01 20:00:39 +01:00

json.hpp

Keep user macros named EMPTY or MEMBERS out of the member-count dispatch

2026-09-23 20:28:37 +02:00