Why do I get this linker error in an assembly

  • Thread starter Thread starter Ralf Jablonski
  • Start date Start date
R

Ralf Jablonski

Help !

I have created a Visual C++ class library (.net assembly) project with two
classes
named Base and Derived where Derived inherits from Base.
During link I get the following linker error:

Test.obj : error LNK2001: Unresolved external symbol "void __cdecl
__CxxCallUnwindDtor(void (__thiscall*)(void *),void *)"
(?__CxxCallUnwindDtor@@$$J0YAXP6EXPAX@Z0@Z)

If I disable exception handling for the compiler (remove /EHsc) then the
assembly is created.
Is exception handling not allowed with inheritance in C++ ?

I'm looking for this issue over a week and found no solution.
Does nobody else run in this linker error ???

Here is the simplest example code:

#pragma once
using namespace System;
namespace Test
{
public __gc class Base
{
public:
Base(void){}
~Base(void){}
};

public __gc class Derived : public Base
{
public:
Derived(void){}
~Derived(void){}
};
}
 
Ralf,
I have created a Visual C++ class library (.net assembly) project with two
classes
named Base and Derived where Derived inherits from Base.
During link I get the following linker error:

Test.obj : error LNK2001: Unresolved external symbol "void __cdecl
__CxxCallUnwindDtor(void (__thiscall*)(void *),void *)"
(?__CxxCallUnwindDtor@@$$J0YAXP6EXPAX@Z0@Z)

If I disable exception handling for the compiler (remove /EHsc) then the
assembly is created.
Is exception handling not allowed with inheritance in C++ ?

I'm looking for this issue over a week and found no solution.
Does nobody else run in this linker error ???
Click to expand...

Can you show us the exact command lines you're building with?

I tried repro'ing this with your example, and couldn't. It sure built OK
without /EHsc, I got a different error, but with it adding msvcrt[d].lib to
the linking libraries list resolved the issue.
 
Hello Tomas,
thanks very much for your tip.
If I add msvcrt[d].lib to the asm, the external is resolved.
I go on without /EHsc switch and use the allowed exception handling syntax
of .NET.
Thanks again :)
Ralf

Tomas Restrepo (MVP) said:
Ralf,
I have created a Visual C++ class library (.net assembly) project with two
classes
named Base and Derived where Derived inherits from Base.
During link I get the following linker error:

Test.obj : error LNK2001: Unresolved external symbol "void __cdecl
__CxxCallUnwindDtor(void (__thiscall*)(void *),void *)"
(?__CxxCallUnwindDtor@@$$J0YAXP6EXPAX@Z0@Z)

If I disable exception handling for the compiler (remove /EHsc) then the
assembly is created.
Is exception handling not allowed with inheritance in C++ ?

I'm looking for this issue over a week and found no solution.
Does nobody else run in this linker error ???
Click to expand...

Can you show us the exact command lines you're building with?

I tried repro'ing this with your example, and couldn't. It sure built OK
without /EHsc, I got a different error, but with it adding msvcrt[d].lib to
the linking libraries list resolved the issue.
Click to expand...
 
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