Pure virtual functions generate bogus link_name.

[jpathy]

Hello,
I am using bindgen to generate code from C++ headers and if i disable name mangling the resulting link_name for functions just become function_name, but the library symbols are of form someprefix_classname_function_name. I am assuming it's a bit of namespace issue. Is there any way to achieve this?

[emilio]

Can you put an example? In general disabling name mangling is only supported to workaround old clang bugs in C, like #528.

[jpathy]

I am using steamworks sdk. Here is some snippet of a header file.

class ISteamUser
{
public:
	virtual HAuthTicket GetAuthSessionTicket( void *pTicket, int cbMaxTicket, uint32 *pcbTicket ) = 0;
}

Here is the relevant generated rust code. It fails to link with test program.

#[repr(C)]
pub struct ISteamUser__bindgen_vtable(::std::os::raw::c_void);
#[repr(C)]
#[derive(Debug, Copy, Clone)]
pub struct ISteamUser {
    pub vtable_: *const ISteamUser__bindgen_vtable,
}
extern "C" {
    #[link_name = "\u{1}GetAuthSessionTicket"]
    pub fn ISteamUser_GetAuthSessionTicket(
        this: *mut ::std::os::raw::c_void,
        pTicket: *mut ::std::os::raw::c_void,
        cbMaxTicket: ::std::os::raw::c_int,
        pcbTicket: *mut root::uint32,
    ) -> root::HAuthTicket;
}

If i inspect the supplied library with the sdk.

$ nm ~/Downloads/sdk/redistributable_bin/linux64/libsteam_api.so |grep GetAuthSession
0000000000021f70 T SteamAPI_ISteamGameServer_GetAuthSessionTicket
000000000001f810 T SteamAPI_ISteamUser_GetAuthSessionTicket

I had to patch the generated code prefixing link_name with SteamAPI_$CLASS.

[emilio]

Oh ok, so the problem here is two. First of all we generate a link name for a pure virtual method, which is wrong. Then there's the long-standing problem that we don't support generating vtables properly, because of C++ compiler differences.

Let's fix the first one since at least that will fix the linking error.

[emilio]

#1199