Re: Ada Core Technologies announces GNATCOM

[Robert Dewar <robert_dewar@my-deja.com>]

In article <38f52ea8.0@news.pacifier.com>,
  "DuckE" <nospam_steved@pacifier.com> wrote:
> To quote K&R section 6.2:
> "There are a number of restrictions on C structures.  The
essential rules
> are that the only operations that you can perform on a
structure are take
> its address with &, and accesss one of its members.  This
implies that
> structures may not be assigned or copied as a unit, and that
they can not be
> passed to or returned from functions.  (These restrictions
will be removed
> in forthcoming versions.)"

Well yes, of course in the original K&R C you could not pass
struct parameters at all, so the issue does not arise.

> As I recall a number of 'C' compilers considered a structure
to be more like
> an array than like a single variable, so structures were
implicitly passed
> by reference (in the same manner as arrays still are).

I never used a C compiler this broken, although there may have
been some. It is fundamental to the C model of parameter
passing that a called function can modify the parameter without
affecting the caller. Again I wonder if you are remembering
typical C code in which structs are passed by pointer. It is
really QUITE unusual to see C code where structs are passed by
value.

There were several C compilers prior to ANSI that did implement
this extension, and implemented it correctly (gcc was one such
compiler, most certainly no version of gcc has had this serious
bug!)



>
> BTW:  I vote for the Import(Ansi_C,...)  which should solve
the problem more
> easily in new code.
>
> SteveD
>
>


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