+ /* SIGFPE both on div/mod by zero and on INT_MIN / -1, which would give
+ * a value of INT_MAX+1. Note that INT_MIN * -1 gives INT_MIN for me, which
+ * is a bug somewhere in [gcc 4.2.1, FreeBSD, amd64]. In fact, -N*-M where
+ * -N*M is INT_MIN will yielf INT_MIN.
+ * Since we don't support floating point, this is somewhat simpler.
+ * Ideally, we'd return an error, but since we overflow for all other
+ * arithmetic, consistency suggests otherwise, but what's the correct value
+ * to use? There is none.
+ * The C standard guarantees overflow for unsigned arithmetic but signed
+ * overflow invokes undefined behaviour; in practice, this is overflow
+ * except for converting INT_MIN to INT_MAX+1. We also can't guarantee
+ * that long/longlong larger than int are available, or we could just work
+ * with larger types. We should consider whether to guarantee 32bit eval
+ * and 64-bit working variables, with errors returned. For now ...
+ * So, the only SIGFPEs occur with a non-shrinking div/mod, thus -1; we
+ * can just let the other invalid results occur otherwise, as they have
+ * until now. For this one case, we can coerce.
+ */
+ if (y == -1 && x == LLONG_MIN && op != '*')
+ {
+ DEBUG(D_expand)
+ debug_printf("Integer exception dodging: " PR_EXIM_ARITH "%c-1 coerced to " PR_EXIM_ARITH "\n",
+ LLONG_MIN, op, LLONG_MAX);
+ x = LLONG_MAX;
+ continue;
+ }
+ if (op == '*')
+ x *= y;
+ else
+ {
+ if (y == 0)
+ {
+ *error = (op == '/') ? US"divide by zero" : US"modulo by zero";
+ x = 0;
+ break;
+ }
+ if (op == '/')
+ x /= y;
+ else
+ x %= y;
+ }
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