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, 14 insertions, 0 deletions

diff --git a/tests/custom/04_bugs/30_nan_strict_equality b/tests/custom/04_bugs/30_nan_strict_equality
new file mode 100644
index 0000000..4ec32e2
--- /dev/null
+++ b/tests/custom/04_bugs/30_nan_strict_equality
@@ -0,0 +1,14 @@
+When comparing `nan` with `nan` for strict equality or inequality, the
+VM incorrectly treated the result as `true` or `false` respectively.
+
+-- Testcase --
+{{ NaN === NaN }}
+{{ NaN !== NaN }}
+{{ uniq([NaN, NaN]) }}
+-- End --
+
+-- Expect stdout --
+false
+true
+[ "NaN" ]
+-- End --