Problem with `string', threading and shared libraries.

[Carlo Wood]

When someone compiles a shared library that exports functions
with `string' in their signature - a problem occurs when
people who want to use that library use a different threading
model - even if both the library and the user application are
single threaded!

The problem is that when _NOTHREADS is defined
(See http://www.sgi.com/tech/stl/thread_safety.html )
then a `string' is defined as

basic_string<char, string_char_traits<char>, __default_alloc_template<false, 0> >

while people who use a compile with for instance POSIX threads
will have a `string' defined as

basic_string<char, string_char_traits<char>, __default_alloc_template<true, 0> >

The result is that calls to, say

  some_library_function(string &param);

will fail with an undefined symbol.

I was wondering, how can it be that `string' has a different
mangling on different compilers/machines?  Isn't that a bug?
If not, then can you tell me what is the appropriate way to
solve this problem (from the point of view of the developer
of the shared library)?

Thanks,

-- 
Carlo Wood <carlo@alinoe.com>