Should compilers ignore unused variables that result in constructors or destructors being run?

Question

I have some code that I put in a destructor to ensure it is run both on normal exit and exception stack unwinding:

struct withProtectedClose {

  ~withProtectedClose() {
    // Do some cleanup here...
  }
};

void test() {
  withProtectedClose close;

  // Do some work before closing
}

Yet the g++ compiler (g++ (GCC) 3.4.6 20060404 (Red Hat 3.4.6-11)) is complaining:

test.cpp: In function `void test()':
test.cpp:28: warning: unused variable 'close'

I can silence it by referring to the variable somehow, but that muddies the code only to silence the compiler, not how I want my code influenced.

Shouldn't the fact that there is a destructor be enough to clue the compiler in that it makes no difference that there is no use of the variable after construction?

Assuming the compiler cannot be shut up while still getting notices of legitimate unused variables, is there a way to silence this one only other than by using it?

Answer 1

I'd tend to think it is a bug in the compiler. It is still present in g++ 4.7.1.

As a work around, you may try to define a constructor which does nothing. It suppresses the warning with g++ 4.7.1, I don't know with 3.4.6.