Self-referential initialization

[Risto Lankinen]

Hi!

Is the following construct legal in C++?

int i = i;

It seems to be working on the compilers that I have. If it
indeed is legal, what is the rationale?

Note also that the following very dangerous construct, too,
seems to be working (probably for the same rationale):

int &r = r;

Cheers!

- Risto -

 

[tom_usenet]

Hi!

Is the following construct legal in C++?

int i = i;

It is well-formed (it should compile), but executing it leads to
undefined behaviour, since you are initializing an int with an
indeterminate int value.

It seems to be working on the compilers that I have. If it
indeed is legal, what is the rationale?

The declaritive scope of a variable starts after its declarator but
before its initializer. I suppose it allows things like:

struct A
{
A(A* other);
};

A a = &a;

which might be useful to someone (although I'm not sure that it is
legal).

Note also that the following very dangerous construct, too,
seems to be working (probably for the same rationale):

int &r = r;

Again, well formed, but illegal.

Tom