[Bug c/63420] New: GCC 4.8.2: Bitshift second operand range not as per manual.

[aainscow at uk dot ibm.com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63420

            Bug ID: 63420
           Summary: GCC 4.8.2: Bitshift second operand range not as per
                    manual.
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: aainscow at uk dot ibm.com

Created attachment 33625
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=33625&action=edit
Demo code

Most likely this is simply a problem with the GCC manual.

The GCC documentation states (30th Sept 2014):

-- 
You use the left-shift operator << to shift its first operand's bits to the
left. The second operand denotes the number of bit places to shift. Bits
shifted off the left side of the value are discarded; new bits added on the
right side will all be 0. 

...

For both << and >>, if the second operand is greater than the bit-width of the
first operand, or the second operand is negative, the behavior is undefined. 
--

NOTE: "greater than" not "greater than or equal to".

The following code should therefore not be undefined and return 0.

int main() {
    int a = sizeof(int)*8;
    return ((int)1) << a;
}

However:
aainscow@morwenna:~/cake$ gcc bitshift_bug.c 
aainscow@morwenna:~/cake$ ./a.out ; echo $?
1

Most likely this is a problem with documentation.