mod(event): merge the declarations of the tagged unions alongside the fields

src/event.zig

@@ -54,6 +54,19 @@ pub fn mergeTaggedUnions(comptime A: type, comptime B: type) type {
         i += 1;
     }
 
+    const a_enum_decls = @typeInfo(A).@"union".decls;
+    const b_enum_decls = @typeInfo(B).@"union".decls;
+    var decls: [a_enum_decls.len + b_enum_decls.len]std.builtin.Type.Declaration = undefined;
+    var j: usize = 0;
+    for (a_enum_decls) |decl| {
+        decls[j] = decl;
+        j += 1;
+    }
+    for (b_enum_decls) |decl| {
+        decls[j] = decl;
+        j += 1;
+    }
+
     const log2_i = @bitSizeOf(@TypeOf(i)) - @clz(i);
 
     const EventType = @Type(.{ .int = .{
@@ -72,7 +85,7 @@ pub fn mergeTaggedUnions(comptime A: type, comptime B: type) type {
         .layout = .auto,
         .tag_type = Event,
         .fields = fields[0..],
-        .decls = &.{},
+        .decls = if (decls.len != 0) decls[0..] else &.{},
     } });
 }