Re: [RFC, PATCH] shrink struct vectorlike_header #2

[Paul Eggert]

> +struct large_vector
> +{
> +  union {
> +    struct large_vector *vector;
> +#if USE_LSB_TAG
> +    /* We need to maintain ROUNDUP_SIZE alignment for the vector member.  */
> +    unsigned char c[vroundup (sizeof (void *))];
> +#endif

That 'void *' should be 'struct large_vector *', mostly for readability
(but also for weird architectures where different pointer types have
different sizes).

> +/* Size of the struct buffer part beyond leading
> +   Lisp_Objects, in word_size units.  */
> +
> +#define BUFFER_REST_SIZE                                               \
> +  ((sizeof (struct buffer) - header_size) / word_size - BUFFER_LISP_SIZE)

This assumes (sizeof (struct buffer) - header_size) is a
multiple of word_size, but that's not necessarily the case.  Does it
matter that BUFFER_REST_SIZE might be incorrect?  If so, it needs to
be fixed; if not, there should be a comment explaining why it doesn't
matter whether the value is correct.

Otherwise, looks good; thanks.