Re: [cxx-abi-dev] Deleted virtual functions
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Re: [cxx-abi-dev] Deleted virtual functions
- To: Dennis Handly <dhandly@xxxxxxxxxx>
- Subject: Re: [cxx-abi-dev] Deleted virtual functions
- From: Sean Perry <perry@xxxxxxxxxx>
- Date: Fri, 29 May 2009 11:07:26 -0400
The C linkage would be a problem on platforms that use a different calling.
The compiler is going to generate code that assumes the functions pointed
to by the virtual function table have C++ linkage. These functions should
have C++ linkage too.
--
Sean Perry
Compiler Development
IBM Canada Lab
(905)-413-6031 (tie 313-6031), fax (905)-413-4839
Dennis Handly
<dhandly@xxxxxxxx
om> To
jason@xxxxxxxxxx,
05/28/2009 10:07 mark@xxxxxxxxxxxxxxxx
PM cc
cxx-abi-dev@xxxxxxxxxxxxxxxx,
daveed@xxxxxxx
Subject
Re: [cxx-abi-dev] Deleted virtual
functions
Looks good.
>From: David Vandevoorde <daveed@xxxxxxx>
>I noticed that there isn't actually a requirement to point virtual
>table entried for pure virtual functions at __cxa_pure_virtual. Is
>that intentional or just sloppy wording?
Well, why have __cxa_pure_virtual without using it? ;-)
I have a suggestion for the signature for __cxa_pure_virtual and the new
__cxa_deleted_virtual:
extern "C" void __cxa_deleted_virtual(void *this_ptr);
extern "C" void __cxa_pure_virtual(void *this_ptr);
Where this_ptr can be cast to a dummy polymorphic class to get the class
name to print a nicer message:
// A dummy polymorphic class to make typeid() do the work below.
class pv_dummy {
public:
virtual void dummy_func();
};
extern "C" {
extern void abort();
void __cxa_pure_virtual (void *this_ptr)
{
pv_dummy *obj = (pv_dummy*)this_ptr;
const char *mangled_name = typeid(*obj).name();
const char *demangled_name = abi::__cxa_demangle(mangled_name, 0, 0,
0);
if (!demangled_name) // out of space?
demangled_name = mangled_name;
fprintf(stderr, "aCC runtime: pure virtual function called for class
\"%s\".
\n", demangled_name);
abort();
}
}
--Apple-Mail-17--1051914877
filename=deleted_funcs.diffs
+ <li>If C::f is a pure virtual function, the corresponding virtual table
+ entry may point to __cxa_pure_virtual
Did you want to explain why you used "may"?
Is this the case of declaring it pure but still having a definition?
(for the destructor)