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From "Roy T. Fielding" <field...@gbiv.com>
Subject Re: freezing 1.3 tonight
Date Fri, 02 May 2008 02:34:43 GMT
On May 1, 2008, at 4:44 PM, Jim Jagielski wrote:

> On Thu, May 01, 2008 at 04:18:32PM -0700, Roy T. Fielding wrote:
>> On May 1, 2008, at 3:33 PM, William A. Rowe, Jr. wrote:
>>> Christopher Key wrote:
>>>>>
>>>> I'm not sure whether this has been covered already, and whether it
>>>> needs to go in during a major release, but is there any chance of
>>>> adding apr_int8_t and apr_uint8_t typedefs?
>>
>> Why?  The type char is defined by the C standard to be an 8bit signed
>> integer.
>
> Huh? 'char' may or may not be signed, the spec doesn't specify which,
> except for the condition that if a "real" character is stored
> in 'char' then that value is unsigned. But if I store, for example,
> 0xfb in there, (and 0xfb isn't a "real" character), then whether
> the value of that char is positive or negative (and thus, whether
> signed) is impl dependent.
>
> The 'signed' qualifier is redundant for all types except 'char'

Er, except that compiler implementations since K&R1 do implement
char as signed because that's how the PDP-11 worked.  Portability
would suck otherwise due to integral types (including char) being
promoted to a signed integer when used in an integer context.

In any case, the patch as given will cause APR to fail compilation
on those platforms in which CHAR_BIT != 8 and there is no OS-defined
int8_t type (not required until C99).

+if test "$ac_cv_define_stdint_types" = "yes"; then
+    signed_byte_value=int8_t
+    unsigned_byte_value=uint8_t
+elif test "$ac_cv_define_char_bit_octet" = "yes"; then
+    signed_byte_value="signed char"
+    unsigned_byte_value="unsigned char"
+else
+    # no known value for 8 bit type
+    AC_ERROR([could not detect a 8-bit integer type])
+fi

The question is, why on earth would we want to break APR on all
pre-C99 platforms for which CHAR_BIT != 8 when we don't even
give a rat's ass how many bits are in a char type?  I still
don't know why APR would require an int8_t other than char.

I am curious if one of the EBCDIC platforms manages to do
integral promotion differently.  Try it yourself:

==========================================
% cat test_char.c
/* Test of char signedness
  *
  *     cc -o test_char test_char.c
  *
  * Roy Fielding, 2008
  */
#include <stdio.h>
#include <stdlib.h>

int main (void)
{
     int total;
     char c;

     c = 200;  /* E grave in iso-8859-1 */
     printf("Character c: %c\n", c);
     total = c + 1000;
     printf("c + 1000 = %d\n", total);

     exit(0);
}
% gcc -o test_char test_char.c
% ./test_char   # settings for term is utf-8
Character c: ?
c + 1000 = 944
%               # changed setting to iso-8859-1
% ./test_char
Character c: È
c + 1000 = 944

....Roy
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