[m-rev.] [reuse] diff: no aliases between primitive types

[Nancy Mazur]

> On 30-Mar-2001, Peter Ross <peter.ross at miscrit.be> wrote:
> > I have been thinking about this, I think that for the MLDS backend we
> > are safe.  However for the LLDS backend, we aren't.
> 
> Even for the MLDS back-end, where float arguments are passed unboxed,
> there might be problems because floats in structures are boxed:
> 
> 	:- type foo ---> f(float, float).
> 	:- pred nasty(foo::di, foo::uo) is det.
> 	:- pragma c_code(nasty(X::di, Y::uo), "...").
> 
> where the "..." is some code relying on the representation of `foo',
> which destructively updates the memory used for `X'...

Isn't that dangerous anyway? Defining a type declaratively, and
then `relying' on the representation it will have internally? 
Seems yuk to me. Does this happen often? 

Nancy

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