From cc56577edfadd7685de7fb14c013c5e3a69c28ce Mon Sep 17 00:00:00 2001
From: Michael Bradshaw <github@mjb.io>
Date: Fri, 20 Oct 2023 07:20:01 -0600
Subject: [PATCH] Return zero for NaN-to-int lossy casts

Fixes #15038.

The goal here is to guarantee lossyCast() is panic-free and always safe.
---
 lib/std/math.zig | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/lib/std/math.zig b/lib/std/math.zig
index 336007be57..817a98f314 100644
--- a/lib/std/math.zig
+++ b/lib/std/math.zig
@@ -1214,7 +1214,9 @@ pub fn lossyCast(comptime T: type, value: anytype) T {
                     }
                 },
                 .Float, .ComptimeFloat => {
-                    if (value >= maxInt(T)) {
+                    if (isNan(value)) {
+                        return 0;
+                    } else if (value >= maxInt(T)) {
                         return @as(T, maxInt(T));
                     } else if (value <= minInt(T)) {
                         return @as(T, minInt(T));
@@ -1234,6 +1236,7 @@ test "lossyCast" {
     try testing.expect(lossyCast(u32, @as(i16, -255)) == @as(u32, 0));
     try testing.expect(lossyCast(i9, @as(u32, 200)) == @as(i9, 200));
     try testing.expect(lossyCast(u32, @as(f32, maxInt(u32))) == maxInt(u32));
+    try testing.expect(lossyCast(u32, nan(f32)) == 0);
 }
 
 /// Performs linear interpolation between *a* and *b* based on *t*.