Open Radar

 
Summary:
NSLog, +stringWithFormat, -initWithFormat:arguments and CFStringCreateWithFormatAndArguments (at least) behave wrong with positional arguments that skip over the first argument.

Steps to Reproduce:

Compile the provided code.

Expected Results:

No output should be generated.

Actual Results:

012-05-10 11:33:38.029 bjc[18467:707] Problem: "%2$@ %2$@ %2$@ %2$@" != "%1$@ %1$@ %1$@ %1$@"
2012-05-10 11:33:38.031 bjc[18467:707] Problem: "%3$@ %3$@ %3$@ %3$@" != "%1$@ %1$@ %1$@ %1$@"
2012-05-10 11:33:38.032 bjc[18467:707] Problem: "%4$@ %4$@ %4$@ %4$@" != "%1$@ %1$@ %1$@ %1$@"
2012-05-10 11:33:38.033 bjc[18467:707] Problem: "     %2$@ %3$@ %4$@" != "     %1$@ %2$@ %3$@"
2012-05-10 11:33:38.034 bjc[18467:707] Problem: "%1$@      %3$@ %4$@" != "%1$@      %2$@ %3$@"
2012-05-10 11:33:38.034 bjc[18467:707] Problem: "%1$@ %2$@      %4$@" != "%1$@ %2$@      %3$@"
2012-05-10 11:33:38.035 bjc[18467:707] Problem: "%4$@ %3$@ %2$@     " != "%3$@ %2$@ %1$@     "
2012-05-10 11:33:38.036 bjc[18467:707] Problem: "%4$@ %3$@      %1$@" != "%3$@ %2$@      %1$@"
2012-05-10 11:33:38.036 bjc[18467:707] Problem: "%4$@      %2$@ %1$@" != "%3$@      %2$@ %1$@"

Regression:
Seems that this bug has existed since long time ago.

Notes:
Probably a duplicated of rdar://8045892 but at https://devforums.apple.com/message/659268 the user big3 dismissed it as “not a bug”, which I think this other radar proves wrong.

I have been able to reproduce the bug in 10.7.3, but also in Mac OS X 10.6 and iOS 5.0/5.1.

--- interpolations2.m ---

// clang -objc -framework Foundation  -g interpolations2.m

#import <Foundation/Foundation.h>

int main(int argc, char **argv) {
	@autoreleasepool {
		NSArray *array = [NSArray arrayWithObjects:
                           @"%1$@ %2$@ %3$@ %4$@",
                           @"%2$@ %3$@ %4$@ %1$@",
                           @"%3$@ %4$@ %1$@ %2$@",
                           @"%4$@ %1$@ %2$@ %3$@",
                           @"%1$@ %1$@ %1$@ %1$@",
                           @"%2$@ %2$@ %2$@ %2$@",
                           @"%3$@ %3$@ %3$@ %3$@",
                           @"%4$@ %4$@ %4$@ %4$@",
                           @"     %2$@ %3$@ %4$@",
                           @"%1$@      %3$@ %4$@",
                           @"%1$@ %2$@      %4$@",
                           @"%1$@ %2$@ %3$@     ",
                           @"%4$@ %3$@ %2$@ %1$@",
                           @"%4$@ %3$@ %2$@     ",
                           @"%4$@ %3$@      %1$@",
                           @"%4$@      %2$@ %1$@",
                           @"     %3$@ %2$@ %1$@",
                           nil];

     for (NSString *frmt in array) {
          NSString *string = [NSString stringWithFormat:frmt, @"%1$@", @"%2$@", @"%3$@", @"%4$@"];
          if (![frmt isEqualToString:string]) {
               NSLog(@"Problem: \"%@\" != \"%@\"", frmt, string);
          }
     }

	 char **carray = calloc(17, sizeof(char *));
	carray[0] = "%1$s %2$s %3$s %4$s";
    carray[1] = "%2$s %3$s %4$s %1$s";
    carray[2] = "%3$s %4$s %1$s %2$s";
    carray[3] = "%4$s %1$s %2$s %3$s";
    carray[4] = "%1$s %1$s %1$s %1$s";
    carray[5] = "%2$s %2$s %2$s %2$s";
    carray[6] = "%3$s %3$s %3$s %3$s";
    carray[7] = "%4$s %4$s %4$s %4$s";
    carray[8] = "     %2$s %3$s %4$s";
    carray[9] = "%1$s      %3$s %4$s";
    carray[10] = "%1$s %2$s      %4$s";
    carray[11] = "%1$s %2$s %3$s     ";
    carray[12] = "%4$s %3$s %2$s %1$s";
    carray[13] = "%4$s %3$s %2$s     ";
    carray[14] = "%4$s %3$s      %1$s";
    carray[15] = "%4$s      %2$s %1$s";
    carray[16] = "     %3$s %2$s %1$s";

	 char *cstring = calloc(20, sizeof(char));

	 for (int idx = 0; idx < 17; idx++) {
		 sprintf(cstring, carray[idx], "%1$s", "%2$s", "%3$s", "%4$s");
		 if (strncmp(cstring, carray[idx], 20) != 0) {
			 NSLog(@"CProblem: \"%s\" != \"%s\"", carray[idx], cstring);
		 }
	 }

	 return 0;
	}
}

--- EOF ---