On some platforms, such as FreeBSD and Oracle Linux, symbols defined
in the crt0 setup routine are exported from shared libraries. So
ignore the symbols that would be exported even in an empty shared
library.
Rust 1.58.0 unfortunately doesn't provide facilities to control symbol
visibility/presence, but we care about controlling the list of
symbols exported from libruby-static.a and libruby.so.
This commit uses `ld -r` to make a single object out of rustc's
staticlib output, libyjit.a. This moves libyjit.a out of MAINLIBS and adds
libyjit.o into COMMONOBJS, which obviates the code for merging libyjit.a
into libruby-static.a. The odd appearance of libyjit.a in SOLIBS is also
gone.
To filter out symbols we do not want to export on ELF platforms, we use
objcopy after the partial link. On darwin, we supply a symbol list to
the linker which takes care of hiding unprefixed symbols.
[Bug #19255]
Co-authored-by: Nobuyoshi Nakada <nobu@ruby-lang.org>
The original st.c was public domain hash table implementation, but
Ruby's st.c is highly modified, and its data structure is not
compatiblie with the original one.
Therefore, when creating an extension library to wrap C code that uses
the original st.c, the symbols conflict, which leads to segfault.
This changes the prefix `st_*` of st.c functions to `rb_st_*` for
reflecting that they are specific to Ruby's, and avoid symbol conflicts.