[dmd-internals] Fwd: DWARF issue 100504, "Extensions for D arrays, associative arrays, and delegates"

[Martin Nowak]

> Robert,
>
> I'm a member of the DWARF committee.  In our last meeting, I was assigned
> the task of understanding your proposal and helping to turn it into a
> formal proposal (with page reference, edit directions and the final  
> formal
> text).
>
> If you don't mind, I'd like to know a bit more about the background of  
> the
> proposal.
>
> For example, are you working with a compiler, a debugger or both?  Are
> these concepts core features of D or standard user features (e.g., are  
> they
> like Fortran COMMON, which is a core feature with important semantics or
> like Pascal WITH, which is a notational convenience)?  Are these D  
> features
> primitives (like C++'s "bool") or the result of composition (like "const
> long long int")?
>
> As I understand your suggestion, I think it's possible to get the same
> effect with a smaller change to DWARF.  For example we could add a new
> attribute and define dynamic array types this way:
>
> DW_TAG_structure_type                         // A structure
>  DW_AT_D_language_dynamic_array_descriptor   // Attribute tells consumer
> what this is
>  DW_AT_name [pointer to "darray"]
>  [specification of an size_t named "length"}
>  [specification of a T* pointer named "ptr"]
>
> In other words, as though it were this C code but with the D-language  
> flag
> added and something useful where I have "...":
>
>    typedef ... T;
>
>    typedef struct darray_struct {
>        size_t  length;
>        T      *ptr;
>    } darray;
>
> Similarly we could add DW_AT_D_language_associative_array and
> DW_A_D_language_delegate to standard structure definitions.
>
> Would this simpler proposal work as well for your purposes?
>
> Thanks for any help you can give me,
>
>        -John

This would indeed be exactly what we need.