http://llvm.org/bugs/show_bug.cgi?id=10120
Summary: Wrong vtable for template class instantiated with
anonymous type
Product: clang
Version: 2.9
Platform: Macintosh
OS/Version: MacOS X
Status: NEW
Severity: normal
Priority: P
Component: C++
AssignedTo: [email protected]
ReportedBy: [email protected]
CC: [email protected], [email protected]
Created an attachment (id=6726)
--> (http://llvm.org/bugs/attachment.cgi?id=6726)
Sample project to show problem
If in a header I declare a template class like this:
// header.h
#include <assert.h>
#include <typeinfo>
template <typename T>
class klass
{
char const* tn1 () const { return typeid(T()).name(); }
virtual char const* tn2 () const { return typeid(T()).name(); }
public:
void test () const { assert(tn1() == tn2()); }
};
Then in two different translation units instantiate the template class with
identically named types, but from anonymous namespaces, example:
// foo.cc
#include "header.h"
namespace { struct my_type_t { }; }
void foo () { klass<my_type_t> foo_instance; foo_instance.test(); }
// bar.cc
#include "header.h"
namespace { struct my_type_t { }; }
void bar () { klass<my_type_t> bar_instance; bar_instance.test(); }
Then the two instances will share the same vtable, meaning calling tn2() on
either will return the same value, whereas calling tn1() will return different
values.
The assertion in test() will fail for one of the two instances.
To test this, save the 3 files above and add main.cc as:
// main.cc
void foo ();
void bar ();
int main (int argc, char const *argv[])
{
foo();
bar();
return 0;
}
Then in Terminal run:
% clang++ {foo,bar,main}.cc && ./a.out
The result I get is:
Assertion failed: (tn1() == tn2()), function test, file ./header.h, line 10.
I also attached an archive with the four files + build.sh.
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