[m-rev.] for review: merge foreign_type pragma on to the main branch

[Tyson Dowd]

On 23-Oct-2001, Peter Ross <peter.ross at miscrit.be> wrote:
> On Tue, Oct 23, 2001 at 05:06:38PM +1000, Tyson Dowd wrote:
> > On 22-Oct-2001, Peter Ross <peter.ross at miscrit.be> wrote:
> > > 
> > > compiler/ilds.m:
> > >     The CLR spec requires that System.Object and System.String be
> > >     treated specially in the IL assembly (you have to use the name
> > >     object and string instead of the System.* names), so add them as
> > >     base types.
> > 
> > Actually you are adding them as "simple types".
> > 
> > Are you sure this is the case? 
> > 
> > il_string_class_name = il_system_name(["String"]).
> > il_generic_class_name = il_system_name(["Object"]).
> > 
> > il_generic_type is defined as System.Object, and we don't seem to have
> > problems with that in the IL assembly code.
> > 
> > Can you tell me what the real problem is, or where this limitation is
> > documented?  (or show me an error message or something?).
> > 
> The .NET framework reported a missing method exception when attempting
> to call a method defined in another language.  For example we would have
> the following bit of IL generated by the intgen tool to access the
> method foo in System.Xml.
> 
>     call void System.Xml::foo(class [mscorlib]System.Object)
> 
> however the type signature for foo is different
> 
>     void System.Xml::foo(object)
> 
> This never occurs in generated Mercury code because we always use
> System.Object and never object so the signatures appear the same to the
> runtime!

Oh right, I remember now.  But we are actually breaking the rules, so
does your change ensure that we no longer break the rules as well?

> For the reference, section 7.2 of Parition II states that CLI builtin
> value types (is the reference here to value types a bug in the spec as
> System.String and System.Object are builtin types but not value types?)
> shall only be referenced in signatures by their special encodings.  See
> Parition I section 8.2.2 for the list of all the builtin types which
> includes object and string.
> 
> Does this help?

Yes, a great deal, thanks.  Can you put a comment to this effect in the
code somewhere using section titles instead of numbers -- all this info
is very relevant, and a little more comment in the log message?

-- 
       Tyson Dowd           # 
                            #  Surreal humour isn't everyone's cup of fur.
     trd at cs.mu.oz.au        # 
http://www.cs.mu.oz.au/~trd #
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