From f6a7ba6ab9c3b43961a56b1a54f9107ae06aa343 Mon Sep 17 00:00:00 2001
From: Pablo Alessandro Santos Hugen <phugen@redhat.com>
Date: Thu, 5 Mar 2026 22:03:19 -0300
Subject: [PATCH] std.cli: ?[]T now is null on empty slices

Signed-off-by: Pablo Alessandro Santos Hugen <phugen@redhat.com>
---
 lib/std/cli.zig | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/lib/std/cli.zig b/lib/std/cli.zig
index ec422659b8..f3a13ebf34 100644
--- a/lib/std/cli.zig
+++ b/lib/std/cli.zig
@@ -212,10 +212,17 @@ fn parseBool(comptime T: type, iter: *Iterator) Error!T {
 }
 
 fn parseOptional(comptime T: type, iter: *Iterator, allocator: Allocator) (Error || Allocator.Error)!T {
-    return parseValue(@typeInfo(T).optional.child, iter, allocator) catch |err| switch (err) {
+    const ChildT = @typeInfo(T).optional.child;
+    const val = parseValue(ChildT, iter, allocator) catch |err| return switch (err) {
         Error.MissingValue => null,
         else => err,
     };
+    // Optional steals empty state from slices
+    const child_info = @typeInfo(ChildT);
+    return if (child_info == .pointer and child_info.pointer.size == .slice and val.len == 0)
+        null
+    else
+        val;
 }
 
 inline fn flagName(arg: []const u8) ?[]const u8 {