vm: fix NaN strict equality tests

A performance shortcut in `ucv_is_equal()` incorrectly led to `NaN === NaN`
being true. Fix the issue by only comparing pointers when the involved
types are not doubles.

Due to fixing `NaN !== NaN`, the `uniq()` function now requires a special
case to treat multiple NaNs equal for the sake of generating an array of
unique values.

Signed-off-by: Jo-Philipp Wich <jo@mein.io>

1 files changed, 5 insertions, 0 deletions

diff --git a/lib.c b/lib.c
index 9d7b26a..7b0c9ca 100644
--- a/lib.c
+++ b/lib.c
@@ -2921,6 +2921,11 @@ uc_uniq_ucv_equal(const void *k1, const void *k2)
 	if (!ucv_is_scalar(uv1) && !ucv_is_scalar(uv2))
 		return (uv1 == uv2);
 
+	/* for the sake of array item uniqueness, treat two NaNs as equal */
+	if (ucv_type(uv1) == UC_DOUBLE && ucv_type(uv2) == UC_DOUBLE &&
+	    isnan(ucv_double_get(uv1)) && isnan(ucv_double_get(uv2)))
+	    return true;
+
 	return ucv_is_equal(uv1, uv2);
 }