[m-rev.] for review: check module qualification when testing for type_info

[Tyson Dowd]

On 23-Aug-2001, Zoltan Somogyi <zs at cs.mu.OZ.AU> wrote:
> On 23-Aug-2001, Tyson Dowd <trd at cs.mu.OZ.AU> wrote:
> > I'm not sure what "not compilable" means?  Does it mean the compiler
> > falls over because it assumes that any type with the name "type_info" is
> > private_builtin__type_info?
> 
> I expect so. The compiler does have special handling of type constructors
> named "type_info", because unlike other type constructors, they (and the tuple
> type constructor) take a variable number of arguments.

For the record, the higher order type constructor is treated specially
too.

> 
> > If so isn't this just a plain old bug --
> > the user is allowed to have a type called type_info.
> 
> I agree, but this change should fix that bug. User-defined type names should
> have been module-qualified by the time the code in question is executed,
> and the module name "private_builtin" *is* reserved.

Sorry, I didn't meant to indicate any doubt about that, I think this is
the right change, I just wasn't sure from the comment and the log
message what the intention was.

> We could insist on the type constructor always being module-qualified with the
> module private_builtin, but that may require changing polymorphism and any
> other part of the compiler that introduces typeinfos.
> 
> I think the change is fine, except the comment should explain this
> compiler-phase dependence on the procedure that was fixed.

This is a good idea.

> We should also think about whether that procedure should insist on the tuple
> type having a particular qualification.

I think this is probably the right approach.

Tyson.
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