Use of ranlib or lorder is no longer necessary with current linkers
(probably anything newer than ~1990) and ar's ability to create an object
index and symbol table in the archive.
Currently the build system uses lorder+tsort to sort the .o files in
dependency order so that a single-pass linker can use them. However,
we can use the -s flag to ar to add an index to the .a file which makes
Running ar -s is equivalent to running ranlib afterwards, so we can also
skip the ranlib invocation.
Similarly, we don't have to pass the .o files for shared libraries in
dependency order since both ld.bfd and ld.lld will correctly resolve
references between the .o files.
This removes many fork()+execve calls for each library so should speed up
builds a bit. Additionally lorder.sh uses a regular expression that is not
supported by the macOS libc or glibc and results in many warnings when
cross-building (see D25989).
See also https://www.gnu.org/software/coreutils/manual/html_node/tsort-background.html
for some more background:
This whole procedure has been obsolete since about 1980, because Unix
archives now contain a symbol table (traditionally built by ranlib, now
generally built by ar itself), and the Unix linker uses the symbol table
to effectively make multiple passes over an archive file.
Or alternatively https://www.unix.com/man-page/osf1/1/lorder/:
The lorder command is essentially obsolete. Use the following command in
its place: % ar -ts file.a
This depends on D26042 since otherwise ld complains about duplicate .o files (the only useful thing that lorder did was to remove duplicates)