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References: <bug-34949-13468@http.gcc.gnu.org/bugzilla/>
Subject: [Bug c++/34949] Dead code in empty destructors.
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------- Comment #4 from spark at gcc dot gnu dot org  2008-01-24 18:16 -------
I don't think this can be implemented in the FE,
at least to be really effective.
The more common cases are not really "empty" destructor.
E.g. there's inlining involved:

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

Foo::~Foo()
{
}


class Bar : public Foo
{
public:
  virtual ~Bar();
};

Bar::~Bar()
{
}


where Foo::~Foo() has to be inlined before we can determine
~Bar() is really empty.

But "emptiness" isn't really how we want to decide eliminating those
but rather the dependence on the vtable itself. e.g.:
extern "C" int printf(const char* s);

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

Foo::~Foo()
{
  printf("good bye foo\n");
}


class Bar : public Foo
{
public:
  virtual ~Bar();
};

Bar::~Bar()
{
  printf("good bye bar\n");
}

In this case, there's no need for vtable update inside the destructor
(which is more common).


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34949