http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56468
Bug #: 56468
Summary: Clang exposes bug with unexpected forward-declaration
of type_info
Classification: Unclassified
Product: gcc
Version: 4.7.2
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: libstdc++
AssignedTo: [email protected]
ReportedBy: [email protected]
The following program fails to compile with Clang++ 3.2:
#include <typeinfo>
#include <exception>
const char* get_name( const std::exception_ptr eptr )
{
return eptr.__cxa_exception_type()->name();
}
int main() {}
The output in the shell is:
$ g++-4.7 -std=c++0x -O3 -Wall -Wextra t.cc -o t
$ clang++-3.2 -std=c++0x -O3 -Wall -Wextra t.cc -o t
t.cc:6:37: error: member access into incomplete type 'const class type_info'
return eptr.__cxa_exception_type()->name();
^
/usr/bin/../lib/gcc/x86_64-linux-gnu/4.7/../../../../include/c++/4.7/bits/exception_ptr.h:144:19:
note: forward declaration of
'std::__exception_ptr::type_info'
const class type_info*
^
1 error generated.
$
The problem is that <typeinfo> includes <exception> before it forward-declares
std::type_info. In <exception>, type_info is used in the context of
std::__exception_ptr, thus Clang generates an implicit forward-declaration for
std::__exception_ptr::type_info and, when used in the above code, consequently
fails.
Further discussion has taken place at <http://stackoverflow.com/q/15098174>.
