[Bug lto/95928] LTO through ar breaks weak function resolution

[hjl.tools at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95928

--- Comment #10 from H.J. Lu <hjl.tools at gmail dot com> ---
(In reply to Andi Kleen from comment #8)
> It works fine without LTO.
> 
> Otherwise the Linux kernel wouldn't work. It relies on this behavior for its
> syscalls.
> 

[hjl@gnu-cfl-2 pr95928]$ make
/usr/gcc-9.3.1-x32/bin/gcc -B./    -c -o dummy.o dummy.c
/usr/gcc-9.3.1-x32/bin/gcc -B./  -c sys_ni.i
/usr/gcc-9.3.1-x32/bin/gcc -B./  -c capability.i
/usr/gcc-9.3.1-x32/bin/gcc-ar rc -o libx.a sys_ni.o capability.o
/usr/gcc-9.3.1-x32/bin/gcc -B./ -O2  -o x dummy.o libx.a
/usr/gcc-9.3.1-x32/bin/gcc -B./ -O2  -o y dummy.o sys_ni.o capability.o
objdump --disassemble=__x64_sys_capget x | grep sys_ni_syscall
  401127:       e8 e5 ff ff ff          callq  401111 <sys_ni_syscall>
objdump --disassemble=__x64_sys_capget y | grep sys_ni_syscall
make: *** [Makefile:20: all] Error 1
[hjl@gnu-cfl-2 pr95928]$ 

> The test case is extracted from there.

Something is missing in this testcase.