clang: no out-of-line virtual method definitions (pure abstract C++ class)

Question

I\'m trying to compile the following simple C++ code using Clang-3.5:

test.h:

class A
{
  public:
    A();
    virtual ~A() = 0;
};

Answer 1

I ended up implementing a trivial virtual destructor, rather than leaving it pure virtual.

So instead of

class A {
public:
    virtual ~A() = 0;
};

I use

class A {
public:
    virtual ~A();
};

Then implement the trivial destructor in a .cpp file:

A::~A()
{}

This effectively pins the vtable to the .cpp file, instead of outputting it in multiple translation units (objects), and successfully avoids the -Wweak-vtables warning.

As a side effect of explicitly declaring the destructor you no longer get the default copy and move operations. See https://stackoverflow.com/a/29288300/954 for an example where they are redeclared.