Re: tar 1.19 - vms time_t is unsigned long. [partial patch[

[John E. Malmberg]

Eric Blake wrote:
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> According to John E. Malmberg on 3/8/2008 1:32 PM:
> | I believe that this attached patch gets intprops.h TYPE_MAXIMUM to
> | handle unsigned types.
>
> TYPE_MAXIMUM already handles unsigned types.  It seems like you have a
> buggy compiler, instead.

I should have re-read the comments in the module.

> |
> | A mask is needed because of an extension that most C compilers have that
> | allow ((unsigned int) -1)  to be tested as being less than 0 through
> | operand promotion.
>
> Huh?  C99 6.3.1.8 states: "Otherwise, if the operand that has unsigned
> integer type has rank greater or equal to the rank of the type of the
<ship>

Yes, I worded that wrong.  The compiler is fine in that regard, my 
verbage was not that precise.

I did this change over 2 months to get things to compile.

> Furthermore, masking with LONG_MAX would break the macro when used with
> 'unsigned long long'.  But since your compiler appears to have a bug, what
> if we do something like this to work around it, instead?
>
> #define TYPE_MAXIMUM(t) \
> ~  ((t) (! TYPE_SIGNED (t) \
>     ? (t) -1 \
> - -     : ~ (~ (t) 0 << (sizeof (t) * CHAR_BIT - 1))))
> +     : ~ (t) (~ (t) 0 << (sizeof (t) * CHAR_BIT - 1))))

I will take my change out and recompile getdate to see if it is really 
needed, and if it is, will look at the output.


But the real problem that I am having is getdate.y is throwing an assert 
if time_t is an unsigned type.  And since my time_t is 32 bits, having 
it signed introduces the Y2038 issue.

Is there some way to change getdate.y to accept an unsigned time_t?

Thanks,
-John