Float values divided by zero should honor signs; fix #3766

It also fixes unexpected resurrection of #3745 by #3752

1 files changed, 4 insertions, 2 deletions

diff --git a/src/vm.c b/src/vm.c
index 1d445563b..3eced7e89 100644
--- a/src/vm.c
+++ b/src/vm.c
@@ -2389,8 +2389,10 @@ RETRY_TRY_BLOCK:
           mrb_int x = mrb_fixnum(regs[a]);
           mrb_int y = mrb_fixnum(regs[a+1]);
           double f;
-          if (y == 0 && x != 0) {
-            f = INFINITY;
+          if (y == 0) {
+            if (x == 0) f = NAN;
+            else if (x > 0) f = INFINITY;
+            else if (x < 0) f = -INFINITY;
           }
           else {
             f = (mrb_float)x / (mrb_float)y;