[cfe-dev] Linker error and obfuscated name

[Reid Kleckner]

On Mon, Aug 3, 2015 at 11:32 AM, Edward Diener <
eldlistmailingz at tropicsoft.com> wrote:

> On 8/3/2015 1:45 PM, Reid Kleckner wrote:
>
>> On Mon, Aug 3, 2015 at 9:56 AM, Edward Diener
>> <eldlistmailingz at tropicsoft.com
>> <mailto:eldlistmailingz at tropicsoft.com>> wrote:
>>
>>     // ex_exception.hpp
>>
>>     #ifndef EX_EXCEPTION_HPP
>>     #define EX_EXCEPTION_HPP
>>     #include <exception>
>>     #include "ex_decl.hpp"
>>     class EX_VISIBLE ex_exception :
>>
>>
>> I think this class should probably be dllexported. It's possible that
>> mingw looks at class visibility as well as dllexport attributes when
>> deciding whether or not to expor tthe RTTI for classes, but I'm pretty
>> sure clang doesn't. We could add that check for compatibility. Is there
>> a compelling reason to not use dllexport on the entire class here?
>>
>
> This is a simple example of a much more complicated problem in the Boost
> serialization library and its source build on Windows. I had made changes
> to get mingw(-64)/gcc to build correctly but have run into this clang
> problem. In essence Boost serialization on Windows exports individual
> member functions rather than entire classes. I doubt I am going to get the
> author of the library to change this, but I will mention to him the clang
> limitation and maybe he can do it.
>
> If you make the change in clang to allow individual member functions to be
> exported/imported for visible classes that would be much better  IMO. But
> past versions of clang on Windows still have this limitation vis-a-vis the
> Boost serialization library. I do not know if other Boost libraries which
> are non-header only use the same technique of exporting/importing
> individual member functions of visible classes on Windows. If they do then
> clang on Windows targeting mingw(-64)/gcc will not work with them either.


Clang supports importing and exporting individual members. That should
already work.

The problem is that we need a way to export the runtime type information
(RTTI). That's why the linker is talking about "typeinfo for
ex_xml_exception". Right now they only way to do that is to export the
whole class, rather than individual members.

The source you provided uses the visibility attribute, though, so I wonder
if mingw does something with that.
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