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Re: gcc visibility used by moz

Daniel Jacobowitz wrote:
On Wed, Jul 12, 2006 at 07:49:21PM +0100, Tristan Wibberley wrote:
No, that's why we need programmer provided attributes. The programmer says:

"the client code needs to know about the existence of this type so it can get pointers and references to instances and pass them back in later and maybe be able to call virtual member functions and access non-static members" by putting it in a header which they document should be included by client code - thus client code includes it and knows about the type. But the programmer says:

"it is documented that the member functions and static members of this type should not need to be accessed outside of the shared object that I will define by use of the linker later on - nor should its constructors/destructors need to be called from outside that shared object, except maybe *this* one and *that* one. Thus the symbols used to lookup those things do not need to be exported from the shared object."

I just don't get it. Why should it matter whether a member function is virtual or not in order to be able to call it from outside this shared object? Either you can access the public members of the class, or you can't. Being able to access some of them and get link errors on others is a very strange default interpretation.

Because virtual functions don't require anything to be exported from a shared object other than a function to get a pointer to an instance.

From C++'s point of view, the hidden attributes should have no effect. From the linker's point of view, they document what the code that links to a shared object will not be using, and so what symbols do not need to be exported.

Tristan Wibberley

These opinions are my own, and do not reflect those of my employer.

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