CODEWITHSUNDEEP
c++c++11clangclang++llvm-clang
Andreas
Andreas

Reputation: 343

C++ linker warning because of virtual destructor / clang

I'm getting a linker warning caused by virtual destructors. My environment is the KEIL compiler v6.5 (clang). 

Warning: L6439W: Multiply defined Global Symbol __clang_call_terminate defined in invalid_group(new.cpp.o) rejected in favor of Symbol defined in .text.__clang_call_terminate(cxa_handlers.cpp.o).

I get this warning as soon as I add the virtual destructor to an interface. For example:

class IInterface {
  virtual ~IInterface(){}

  virtual void doSomething() const = 0;
}

As soon as I implement one single derived class of this interface I get the above mentioned warning. As soon as I remove the virtual destructor, the warning vanishes.

I tried really many things to find out what's the reason, but didn't succeed...

Does someone know how to fix this warning?

Thank you!

Edit: A complete example throwing this warning:

class IInterface {
  public:
  virtual ~IInterface();

  virtual void doSomething() = 0;
};

IInterface::~IInterface() {

}

class SomeClass : public IInterface {
  public:
  virtual void doSomething();
};

void SomeClass::doSomething() {

}

int main() {

}

Upvotes: 4

Views: 1709

Answers (3)

wrapperapps
wrapperapps

Reputation: 988

As mentioned, this was a linker bug which has been fixed in ARM Compiler v6.11 (10/25/2018).

Release notes:

[SDCOMP-30157] In certain circumstances, after discarding a section from a COMDAT ELF section group, the linker could incorrectly report Warning: L6439W: Multiply defined Global Symbol defined in invalid_group() rejected in favour of Symbol defined in (). This has been fixed.

Upvotes: 0

Andreas
Andreas

Reputation: 343

I asked support of ARM and got the information that this warning is spurious. So it seems to be an issue of the current ARM clang compiler toolchain implementation.

Nevertheless thank you all for your responses on this topic.

Upvotes: 3

Stargateur
Stargateur

Reputation: 26757

If you define your function in header you will emit the function each time you include it in a file. To remove this warming you need to define your method outside the declaration

// IInterface.hpp
class IInterface {
public:
  virtual ~IInterface();
}

// IInterface.cpp
IInterface::~IInterface() {}

Upvotes: 2

Related Questions