[boost] Re: Any interest in static_list?

From: Alexander Nasonov (alnsn-mycop_at_[hidden])
Date: 2003-09-29 05:02:47

"John H. Spicer" <jhs_at_[hidden]> writes:
> I don't agree with that interpretation of 3.6.2.  I have always
> assumed that the 3.6.2 was intended to permit an implementation that
> loads object files on-demand, so that the use of an unresolved
> reference to a function or object would cause the object file to be
> loaded and the static initializations to be performed.  In such a
> model, a use of an inline function would only cause the object file to
> be loaded if it happened that the implementation required an
> out-of-line definition in that object file.

Out-of-line definition of inline function can be forced. For example, every 
shared library where static_list is used may have its own out-of-line 
definiton of <code>inline void multiply_defined() {}</code>. 
While linking a shared library this definition cannot be optimized away just 
because at the time of linking it's unknown whether main program has it or 
not. As a result, every shared library where multiply_defined is used 
out-of-line has it. This is truly multiply defined function.
The dilemma for a linker is which multiply_defined to use. Only one among 
all these definitions should be used, otherwise you could end up with two 
different addresses for one function and comparison might give unexpected 
result (not sure about this, correct me if I'm wrong).
I can think of two different stategies: (a) use multiply_defined defined in 
main program and (b) use multiply_defined defined in first loaded shared 
library where it is used.
The first choice is great at runtime because it allows to avoid loading of 
any shared library. The second choice is good for minimizing executable 
size.
Even in case of static linking the question remains. Depending on the answer 
static objects from different TUs might have been initialized. The 
standrard should be more specific about this behavior.

-- 
Alexander Nasonov
Remove minus and all between minus and at from my e-mail for timely response