[Issue 1773] excessively long integer literal

[d-bugmail at puremagic.com]

http://d.puremagic.com/issues/show_bug.cgi?id=1773





------- Comment #3 from aplee at primus.ca  2008-01-17 22:14 -------
I have been able to characterize the problem further by running a piece of the
lexer as a standalone C program:

#include <stdio.h>
#include <stdint.h>
void main() {
  int cnt = 17;
  uint64_t n;
  int r = 16, d;
  printf("Walter's parsing 0xF_FFFF_FFFF_FFFF_FFFF\n");
  n = 0;
  cnt = 17;
  while(cnt--) {
    d = 15; // 0xF_FFFF_FFFF_FFFF_FFFF;
    if (d >= r) break;
    printf("Condition value %llu < %llu\n",n * r + d,n);
    if (n * r + d < n) {
      printf("Overflow\n");
      break;
    }
    n = n * r + d;
    printf("%0d: n = %llu\n",cnt,n);
  }
  printf("Walter's parsing 0x1_0000_0000_0000_0000\n");
  n = 0;
  cnt = 17;
  while(cnt--) {
    if (cnt == 16) d = 1; // 0x1_0000_0000_0000_0000;
    else d = 0;
    if (d >= r) break;
    printf("Condition value %llu < %llu\n",n * r + d,n);
    if (n * r + d < n) {
      printf("Overflow\n");
      break;
    }
    n = n * r + d;
    printf("%0d: n = %llu\n",cnt,n);
  }
}

In running this program which mimics the parsing of the two integer literals
shown above, the problem becomes obvious. It is in the conditional. I do not
know the solution yet.


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