[v3] use -Wl,-z,relro if possible

[Mark Mitchell]

Paolo Carlini wrote:
> Hi Benjamin,
> 
> 
>>For GNU ld that supports -z relro, use it when creating shared object.
>>
> 
> On x86-linux, stock binutils 2.16.1, today I'm seeing a bunch of new
> failures in 21_string:
> 
> FAIL: 21_strings/basic_string/cons/char/6.cc (test for excess errors)
> WARNING: 21_strings/basic_string/cons/char/6.cc compilation failed to
> produce executable

I am seeing these failures as well.  The assembler in my path is (just
plain) 2.16.

For example:

/usr/local/tools/gcc-3.4.0/bin/ld:
testsuite_abi.o(.text._ZNSs12_S_constructIPcEES0_T_S1_RKSaIcESt20forward_iterator_tag[char*
std::basic_string<char, std::char_traits<char>, std::allocator<char>
>::_S_construct<char*>(char*, char*, std::allocator<char> const&,
std::forward_iterator_tag)]+0x91): unresolvable relocation against
symbol `std::__throw_logic_error(char const*)@@GLIBCXX_3.4'

I'm rebuilding from scratch to see if that somehow fixes things, but it
looks like maybe we need some additional configure check to gate your patch.

-- 
Mark Mitchell
CodeSourcery
mark@codesourcery.com
(650) 331-3385 x713