Description of fix

[Christos Zoulas]

On May 10,  6:09pm, aph at redhat.com (Andrew Haley) wrote:
-- Subject: Re: Description of fix

| On 05/10/2011 06:00 PM, Azeem Jiva wrote:
| > Sorry forgot to add that if I try to build a 64bit JVM under Ubuntu 
| > 11.04 with GCC 4.5.2 I get the following compile time error:
| > 
| > /home/azeem/hs/hotspot/src/os/linux/vm/os_linux.cpp: In static member 
| > function ‘static bool os::Linux::hugetlbfs_sanity_check(bool, size_t)’:
| > /home/azeem/hs/hotspot/src/os/linux/vm/os_linux.cpp:2853:43: error: use 
| > of assignment suppression and length modifier together in gnu_scanf format
| > 
| > 
| > The fix is to remove the length modifier.
| 
| That shouldn't be an error, though: it's perfectly correct code.
| I suppose it's a (rather unhelpful) warning that's erroring out
| because of -Werror.

Well, 

The length specifier does not affect the scanning process (i.e.
the scanner does not stop on overflow, it consumes the whole numeric
string) so the length modifier is superfluous on skipped format
specifiers. Perhaps it is better for portability to remove the
length modifier and call it a day.

christos

#include <stdio.h>
#include <inttypes.h>

int
main(int argc, char *argv[])
{
	static const char b[] = "123456789012345";
	uint64_t x64 = 0, y64 = 0;
	uint32_t x32 = 0, y32 = 0;

	sscanf(b, "%" SCNu64 "%" SCNu64, &x64, &y64);
	printf("x=%" PRIu64 " y=%" PRIu64 "\n", x64, y64);

	sscanf(b, "%" SCNu32, &x32, &y32);
	printf("x=%" PRIu32 " y=%" PRIu32 "\n", x32, y32);

	return 0;
}