cc -O2 -pipe  -pthread  -Wall -Wextra getlocalename_l.c -o getlocalename_l -D_GNU_SOURCE -D_BSD_SOURCE -D_ALL_SOURCE -D_DEFAULT_SOURCE  -lm -lpthread 
getlocalename_l.c:9:21: warning: call to undeclared function 'getlocalename_l'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
        const char* name = getlocalename_l(LC_COLLATE, LC_GLOBAL_LOCALE);
                           ^
getlocalename_l.c:9:14: warning: incompatible integer to pointer conversion initializing 'const char *' with an expression of type 'int' [-Wint-conversion]
        const char* name = getlocalename_l(LC_COLLATE, LC_GLOBAL_LOCALE);
                    ^      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
getlocalename_l.c:17:7: warning: incompatible integer to pointer conversion assigning to 'const char *' from 'int' [-Wint-conversion]
        name = getlocalename_l(LC_COLLATE, locale);
             ^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
3 warnings generated.
ld: error: undefined symbol: getlocalename_l
>>> referenced by getlocalename_l.c
>>>               ../out/openbsd/basic/getlocalename_l.o:(main)
>>> referenced by getlocalename_l.c
>>>               ../out/openbsd/basic/getlocalename_l.o:(main)
cc: error: linker command failed with exit code 1 (use -v to see invocation)