reentrant error!

#include <string.h>

void testok(void) reentrant
{ char buff[20];

buff[0]=1;

strcpy(buff,"hello");

//ok: buff = "hello"

}

void testfail(void) reentrant
{ char buff[20];

buff[0]=1; buff[2]=2;

strcpy(buff,"hello");

//fail: buff = "ello"

}

void main(void)
{ testok(); testfail();
}