LLD 13 and GNU ld 2.37 support -z start-stop-gc which allows garbage collection of C identifier name sections despite the __start_/__stop_ references. Simply set the retain attribute so that GCC 11 (if configure-time binutils is 2.36 or newer)/Clang 13 will set the SHF_GNU_RETAIN section attribute to prevent garbage collection. Without the patch, there are linker errors like the following with -z start-stop-gc. ``` ld: error: undefined symbol: __start_SYSTEMD_BUS_ERROR_MAP >>> referenced by bus-error.c:93 (../src/libsystemd/sd-bus/bus-error.c:93) >>> sd-bus_bus-error.c.o:(bus_error_name_to_errno) in archive src/libsystemd/libsystemd_static.a ``` Co-authored-by: Evgeniy Khramtsov <evgeniy@khramtsov.org>
1 files changed, 6 insertions(+), 0 deletions(-) M src/libsystemd/sd-bus/bus-error.h
M src/libsystemd/sd-bus/bus-error.h => src/libsystemd/sd-bus/bus-error.h +6 -0
@@ 28,11 28,17 @@ int bus_error_set_errnofv(sd_bus_error *e, int error, const char *format, va_lis * the bus error table, and BUS_ERROR_MAP_ELF_USE has to be used at * least once per compilation unit (i.e. per library), to ensure that * the error map is really added to the final binary. * * In addition, set the retain attribute so that the section cannot be * discarded by ld --gc-sections -z start-stop-gc. Older compilers would * warn for the unknown attribute, so just disable -Wattributes. */ #define BUS_ERROR_MAP_ELF_REGISTER \ _Pragma("GCC diagnostic ignored \"-Wattributes\"") \ __attribute__ ((__section__("BUS_ERROR_MAP"))) \ __attribute__ ((__used__)) \ __attribute__ ((retain)) \ __attribute__ ((aligned(8))) #define BUS_ERROR_MAP_ELF_USE(errors) \