2.2.2 constant expression range checking

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2 total messages Started by Kenneth Herron Wed, 07 Oct 1992 16:16

#1168

Author: Kenneth Herron
Date: Wed, 07 Oct 1992 16:16

41 lines
2157 bytes

Our gcc has had several of Paul Eggert's patches applied, and I think
one of them is at fault here, so if they're not to be considered 
official then take this with a grain of salt.

This file, compiled with "gcc -c testit.c":
----------------
/* #include <sys/types.h> */
#ifndef u_char
#define u_char  unsigned char
#endif

static u_char badmap[] = {
	'\200', '\201', '\202', '\203', '\204', '\205', '\206', '\207',
};
static char goodmap[] = {
	'\200', '\201', '\202', '\203', '\204', '\205', '\206', '\207',
};
----------------
produces:
----------------
gcc-test.c:8: warning: constant expression out of range for unsigned type
gcc-test.c:8: warning: constant expression out of range for unsigned type
gcc-test.c:8: warning: constant expression out of range for unsigned type
gcc-test.c:8: warning: constant expression out of range for unsigned type
gcc-test.c:8: warning: constant expression out of range for unsigned type
gcc-test.c:8: warning: constant expression out of range for unsigned type
gcc-test.c:8: warning: constant expression out of range for unsigned type
gcc-test.c:8: warning: constant expression out of range for unsigned type
----------------
Uncommenting the #include line and commenting out the #define makes
no difference.

gcc -v returns:

Reading specs from /xbin/gnu/lib/gcc-lib/symmetry-dynix/2.2.2/specs
gcc version 2.2.2
-- 
Kenneth Herron                                   kherron@ms.uky.edu
University of Kentucky                              +1 606 257 2975
Department of Mathematics      I just thought of a neat disproof of
     Fermat's last theorem, but .signatures can only be four lines.

Re: 2.2.2 constant expression range checking

#1169

Author: Paul Eggert
Date: Wed, 07 Oct 1992 18:40

9 lines
861 bytes

>static u_char badmap[] = {
>	'\200', '\201', '\202', '\203', '\204', '\205', '\206', '\207',
>};

>gcc-test.c:8: warning: constant expression out of range for unsigned type

The warning is correct, since '\200' equals -128, and -128 is out of
range for the type unsigned char.  You can fix the problem by writing
0200 instead of '\200'.

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