stdint causes warnings on Tru64

[Bruno Haible]

Hi Paul,

The gnulib-substituted stdint.h causes a compiler warning from the
OSF/1 5.1 cc compiler, at every use of PTRDIFF_MAX or SIG_ATOMIC_MAX.


cc: Warning: test-stdint.c, line 260: In the declaration of 
"verify_error_if_negative_size__", integer overflow occurs in evaluating the 
expression "(((0)+1)<<((64)?(64)-1:0))-1". (intoverfl)
verify (TYPE_MAXIMUM (ptrdiff_t) == PTRDIFF_MAX);
^
cc: Warning: test-stdint.c, line 260: In the declaration of 
"verify_error_if_negative_size__", integer overflow occurs in evaluating the 
expression "((((0)+1)<<((64)?(64)-1:0))-1)*2". (intoverfl)
verify (TYPE_MAXIMUM (ptrdiff_t) == PTRDIFF_MAX);
^
cc: Warning: test-stdint.c, line 273: In the declaration of 
"verify_error_if_negative_size__", integer overflow occurs in evaluating the 
expression "(((0)+1)<<((32)?(32)-1:0))-1". (intoverfl)
verify (TYPE_MAXIMUM (sig_atomic_t) == SIG_ATOMIC_MAX);
^
cc: Warning: test-stdint.c, line 273: In the declaration of 
"verify_error_if_negative_size__", integer overflow occurs in evaluating the 
expression "((((0)+1)<<((32)?(32)-1:0))-1)*2". (intoverfl)
verify (TYPE_MAXIMUM (sig_atomic_t) == SIG_ATOMIC_MAX);
^

IMO warnings in .c files installed by gnulib are acceptable, but warnings
caused by .h files should be avoided. I'm applying this, since it fixes the
warning.


2007-10-28  Bruno Haible  <address@hidden>

        * lib/stdint.in.h (_STDINT_MAX): Subtract 1 from an unused signed
        integer shift in the signed case. Fixes warnings with OSF/1 5.1 cc.

--- lib/stdint.in.h.orig        2007-10-29 03:46:10.000000000 +0100
+++ lib/stdint.in.h     2007-10-29 03:34:10.000000000 +0100
@@ -101,7 +101,10 @@
 #define _STDINT_MAX(signed, bits, zero) \
   ((signed) \
    ? ~ _STDINT_MIN (signed, bits, zero) \
-   : ((((zero) + 1) << ((bits) ? (bits) - 1 : 0)) - 1) * 2 + 1)
+   : /* The expression for the unsigned case.  The subtraction of (signed) \
+       is a nop in the unsigned case and avoids "signed integer overflow" \
+       warnings in the signed case.  */ \
+     ((((zero) + 1) << ((bits) ? (bits) - 1 - (signed) : 0)) - 1) * 2 + 1)
 
 /* 7.18.1.1. Exact-width integer types */