Niels Lohmann 964b433dc7 Force inlining of the serializer helpers only in optimized builds ...

The seven serializer helpers marked JSON_HEDLEY_ALWAYS_INLINE are inlined
at -O0 as well, and GCC and Clang give every inlined copy its own stack
slots there. That made the recursive frame of dump_container() 2304 bytes
with Clang 21 (2048 with GCC 16), against 480 bytes in 3.12.0, so dump()
of a value nested beyond the default recursion depth limit needed 288 KiB
of stack in an unoptimized build and crashed in a 128 KiB musl thread.

Define JSON_INTERNAL_SERIALIZER_INLINE as JSON_HEDLEY_ALWAYS_INLINE when
__OPTIMIZE__ (or _MSC_VER) is defined and as plain inline otherwise, and
use it for these helpers. The frame drops to 320 bytes and dump() needs
48 KiB at the default limit. The -O2 object code is unchanged with Clang 21
and GCC 16.

Update the stack tables in json_recursion_depth_limit.md and
untrusted_input.md: copying and conversion are now the most demanding
operations at -O0.

Fixes #6116.

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

2026-11-13 10:25:10 +01:00

..

nlohmann

Force inlining of the serializer helpers only in optimized builds

2026-11-13 10:25:10 +01:00