Re: Modula-3 grammar ambiguity (a puzzle)

In comp.lang.modula3 Dragi?a Duri&#263; <dragisha@[EMAIL PROTECTED]
> wrote:
> I am writing a parser for Modula-3 and this production puzzled me:

> ObjectType    = [TypeName | ObjectType] [Brand] OBJECT Fields 
>                  [METHODS Methods] [OVERRIDES Overrides] END.

> This rule is single left recursive piece of Modula-3 grammar, IIRC.
> And also, it does not look correct - I can't remember I've seen
> anything except "TypeName" (meaning "qualId | [UNTRACED] ROOT")
> denoting parent type anywhere in Modula-3 sources. It is also
> illogical (to me, at least) to have anonymous type as parent of
> anything, and we will have that if this is declared:

> TYPE
>   My = OBJECT a: CARDINAL; END OBJECT b: CARDINAL; END;

> This "My" is in proper syntax according to above production, but pm3
> did not accept it. I have no reason to believe any Modula-3 compiler
> will. Is there a reason? Do we have an ommision in Modula-3 syntax or
> implementation restriction in our compilers?

Probably, but I wouldn't worry very much, as the feature
to inherit from anonymous object types is of no practical
interest, I think. Have you tried the CM3 compiler, too?

At least I cannot think of a good reason to allow it, but 
perhaps I'm missing something.
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