https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103490
Bug ID: 103490
Summary: Linkage type of typeinfo of polymorphic object with
OOL functions
Product: gcc
Version: 11.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: lizekun.zek at bytedance dot com
Target Milestone: ---
Hi guys,
I found that the linkage of typeinfo of polymorphic object with OOL-functions
is weak, while that is strong for clang, and I want to attach a patch to make
the behavior of the two compilers consistent. However, I can't find the clear
definition of this in Itanium C++ ABI, so here are the questions:
1.It is easy to understand that we make the object with inlined-functions weak,
because it usually appears in a header file and may be defined several times,
so when functions are out-of-line, why do we make it weak?
2.In fact, I prefer the gcc way, are there any cases that show gcc is
better?
This is a case to show the issue.
---
test.h
class A{
public:
virtual const int getA(){} ;
virtual const int getB(){} ;
};
---
testA.cpp
#include<iostream>
#include "test.h"
using namespace std;
class Test : public A {
public:
virtual const int getA() override;
};
const int Test ::getA() {
return 1;
}
int main() {
A * t=new Test();;
cout << dynamic_cast<Test*>(t);
}
---
testB.cpp
#include "test.h"
class Test : A {
public:
virtual const int getB() override;
};
const int Test :: getB() {
return 2;
}
