The linkage for the vtable for any class marked dllimport is generated as a
standard external link rather than a dllimport "__imp_" link. This results in
linker diagnostics such as:
Info: resolving vtable for TestObject by linking to __imp___ZTV10TestObject
(auto-import)
d:/jsupport/mingw/bin/../lib/gcc/mingw32/4.3.3-dw2/../../../../mingw32/bin/ld.exe:
warning: auto-importing has been activated without --enable-auto-import
specified on the command line.
This should work unless it involves constant data structures referencing
symbols from auto-imported DLLs.
The following simple testcase demonstrates this.
----- vttest.cpp -----
struct __attribute__((dllimport)) TestObject
{
virtual void VirtFunc();
};
int main()
{
TestObject obj;
obj.VirtFunc();
return 0;
}
----- vttestdll.cpp -----
struct __attribute__((dllexport)) TestObject
{
virtual void VirtFunc() {}
};
> g++ -shared -o vttest.dll -Wl,--out-implib,libvttest.dll.a vttestdll.cpp
Creating library file: libvttest.a
> g++ -o vttest.exe vttest.cpp libvttest.dll.a
Info: resolving vtable for TestObject by linking to __imp___ZTV10TestObject
(auto-import)
d:/jsupport/mingw/bin/../lib/gcc/mingw32/4.3.3-dw2/../../../../mingw32/bin/ld.exe:
warning: auto-importing has been activated without --enable-auto-import
specified on the command line.
This should work unless it involves constant data structures referencing
symbols from auto-imported DLLs.
--
Summary: Linkage broken for dllimport vtables
Product: gcc
Version: 4.3.3
Status: UNCONFIRMED
Severity: critical
Priority: P3
Component: target
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: tdragon at tdragon dot net
GCC build triplet: mingw32
GCC host triplet: mingw32
GCC target triplet: mingw32
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39578
