Linking problem with lld

[Tijl Coosemans]

On Sun, 3 Mar 2019 15:21:56 +0100 Willem Jan Withagen <wjw at digiware.nl>
wrote:
> First success.
> I used this map, but also needed to fix a .symver:
> ====
>   #define LIBRADOS_C_API_BASE_DEFAULT(fn)       \
> -  asm(".symver _" #fn ", " #fn "@@")
> +  asm(".symver _" #fn ", " #fn "@")
> ====
> That last was more or less guessed from the binutils/docs/ld page.

It's really a bug in lld.  You can add LLD_UNSAFE=yes to the port
Makefile for now.

Here's a simple test case:

% cat test.c
void _test1() {
}
asm(".symver _test1, test1@@");

void test2() {
}
% cat test.map
{
  local: *;
};
% clang70 -shared -o libtest.so test.c -fPIC -Wl,--version-script=test.map
% readelf -s libtest.so | grep test
     8: 0000000000000000     0 FILE    LOCAL  DEFAULT  ABS test.c
     9: 0000000000001090     5 FUNC    LOCAL  DEFAULT    9 _test1
    10: 0000000000001090     5 FUNC    LOCAL  DEFAULT    9 test1
    11: 00000000000010a0     5 FUNC    LOCAL  DEFAULT    9 test2
% clang70 -shared -o libtest.so test.c -fPIC -Wl,--version-script=test.map -fuse-ld=bfd
% readelf -s libtest.so | grep test
     3: 0000000000000280     5 FUNC    GLOBAL DEFAULT   11 test1
    34: 0000000000000000     0 FILE    LOCAL  DEFAULT  ABS test.c
    38: 0000000000000280     5 FUNC    LOCAL  DEFAULT   11 _test1
    42: 0000000000000290     5 FUNC    LOCAL  DEFAULT   11 test2
    46: 0000000000000280     5 FUNC    GLOBAL DEFAULT   11 test1@@

With lld test1 is local.  With GNU ld it's global.  The .symver
directive should override the version script.