std.MultiArrayList: add test coverage for 0-bit structs

closes #10618
solved by #17172

lib/std/array_hash_map.zig

@@ -2336,6 +2336,35 @@ test "sort" {
     }
 }
 
+test "0 sized key" {
+    var map = AutoArrayHashMap(u0, i32).init(std.testing.allocator);
+    defer map.deinit();
+
+    try testing.expectEqual(map.get(0), null);
+
+    try map.put(0, 5);
+    try testing.expectEqual(map.get(0), 5);
+
+    try map.put(0, 10);
+    try testing.expectEqual(map.get(0), 10);
+
+    try testing.expectEqual(map.swapRemove(0), true);
+    try testing.expectEqual(map.get(0), null);
+}
+
+test "0 sized key and 0 sized value" {
+    var map = AutoArrayHashMap(u0, u0).init(std.testing.allocator);
+    defer map.deinit();
+
+    try testing.expectEqual(map.get(0), null);
+
+    try map.put(0, 0);
+    try testing.expectEqual(map.get(0), 0);
+
+    try testing.expectEqual(map.swapRemove(0), true);
+    try testing.expectEqual(map.get(0), null);
+}
+
 pub fn getHashPtrAddrFn(comptime K: type, comptime Context: type) (fn (Context, K) u32) {
     return struct {
         fn hash(ctx: Context, key: K) u32 {

lib/std/multi_array_list.zig

@@ -901,3 +901,52 @@ test "sorting a span" {
         c += 1;
     }
 }
+
+test "0 sized struct field" {
+    const ally = testing.allocator;
+
+    const Foo = struct {
+        a: u0,
+        b: f32,
+    };
+
+    var list = MultiArrayList(Foo){};
+    defer list.deinit(ally);
+
+    try testing.expectEqualSlices(u0, &[_]u0{}, list.items(.a));
+    try testing.expectEqualSlices(f32, &[_]f32{}, list.items(.b));
+
+    try list.append(ally, .{ .a = 0, .b = 42.0 });
+    try testing.expectEqualSlices(u0, &[_]u0{0}, list.items(.a));
+    try testing.expectEqualSlices(f32, &[_]f32{42.0}, list.items(.b));
+
+    try list.insert(ally, 0, .{ .a = 0, .b = -1.0 });
+    try testing.expectEqualSlices(u0, &[_]u0{ 0, 0 }, list.items(.a));
+    try testing.expectEqualSlices(f32, &[_]f32{ -1.0, 42.0 }, list.items(.b));
+
+    list.swapRemove(list.len - 1);
+    try testing.expectEqualSlices(u0, &[_]u0{0}, list.items(.a));
+    try testing.expectEqualSlices(f32, &[_]f32{-1.0}, list.items(.b));
+}
+
+test "0 sized struct" {
+    const ally = testing.allocator;
+
+    const Foo = struct {
+        a: u0,
+    };
+
+    var list = MultiArrayList(Foo){};
+    defer list.deinit(ally);
+
+    try testing.expectEqualSlices(u0, &[_]u0{}, list.items(.a));
+
+    try list.append(ally, .{ .a = 0 });
+    try testing.expectEqualSlices(u0, &[_]u0{0}, list.items(.a));
+
+    try list.insert(ally, 0, .{ .a = 0 });
+    try testing.expectEqualSlices(u0, &[_]u0{ 0, 0 }, list.items(.a));
+
+    list.swapRemove(list.len - 1);
+    try testing.expectEqualSlices(u0, &[_]u0{0}, list.items(.a));
+}