Re: [avr-gcc-list] Support for ATMega256 and ATMega2560

[Dave Hansen]

> From: Joerg Wunsch <address@hidden>
[...]
> The C language (at least starting with `ANSI' C, the old K&R has been
> notorously lax about this) strictly distinguishes pointers of
> different types, i. e. a char * is fundamentally incompatible with an
> int * from the language standard's point of view.  Converting one
> pointer to another one is beyond the guarantees of the standard.  The
> only conversion covered by the standard is that you can convert any
> explicitly typed pointer into a void *, and back from that void * into
> its original type elsewhere (but not into a different one), so it is
> guaranteed the resulting pointer will point again to the same object.

This is correct except for pointers to functions.  There is no guarantee 
that a pointer to function can be converted to a pointer to void and back 
again.  However, the _is_ a guarantee that a pointer to a function of one 
type can be converted to a pointer to a function of any other type and back 
again. So a (void (*)(void)) can serve as a generic pointer to function.

Also, a pointer to void is guaranteed to have the same alignment and 
representation as a pointer to unsigned char.

I figure you know this, just clarifying in case some else doesn't.  Regards,

  -=Dave

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