Niels Lohmann 864ac37cdb Add scalar-on-left overloads for legacy discarded comparisons in C++20 ...

With JSON_USE_LEGACY_DISCARDED_VALUE_COMPARISON=1 and C++20, a scalar on
the left-hand side of <= or >= (e.g., `1 <= discarded`) yielded false
instead of the documented true. The C++20 legacy block only had member
operators, which are only candidates when the basic_json is the left
operand; for a scalar on the left, overload resolution picked the
candidate rewritten from operator<=>, which does not emulate the legacy
behavior. The C++17 branch already has scalar-on-the-left friend
overloads for <= and >=; add the equivalent pair to the C++20 legacy
block.

Added a regression test to tests/src/unit-comparison.cpp covering all
four operand orders for both operators.

Fixes #5665.

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

2026-09-29 23:16:44 +02:00

..

nlohmann

Add scalar-on-left overloads for legacy discarded comparisons in C++20

2026-09-29 23:16:44 +02:00