[Bug target/83110] New: Relocation error when taking address of protected function in shared library.

[yyc1992 at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83110

            Bug ID: 83110
           Summary: Relocation error when taking address of protected
                    function in shared library.
           Product: gcc
           Version: 7.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: yyc1992 at gmail dot com
  Target Milestone: ---

This is very similar to https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65248
although that one is marked as fixed.
(This could be a dup of https://gcc.gnu.org/bugzilla/show_bug.cgi?id=19520 but
I can't really tell...)

The difference from https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65248 is that
this now only happens for me with protected functions and not global variables.

The code to reproduce is

```
__attribute__((visibility("protected")))
void f()
{
}

// __attribute__((visibility("protected")))
// int f;

void f2(void (*cb)(void*))
{
    cb((void*)&f);
}
```

Which gives the error
```
% LANG=C g++ a.cpp -o liba.so -pthread -fPIC -shared
/bin/ld: /tmp/ccvUACGZ.o: relocation R_X86_64_PC32 against protected symbol
`_Z1fv' can not be used when making a shared object
/bin/ld: final link failed: Bad value
collect2: error: ld returned 1 exit status
```