examples: make request_reply slightly more interesting

This is probably the sort of thing that I wouldn't actually think of
having explicit test coverage for if I hadn't accidentally ran across
it while fiddling. I will compensate for this easily by not actually
writing tests at all.

examples/request_reply.zig

@@ -2,7 +2,7 @@ const std = @import("std");
 const nats = @import("nats");
 
 fn onMessage(
-    userdata: *bool,
+    userdata: *u32,
     connection: *nats.Connection,
     subscription: *nats.Subscription,
     message: *nats.Message,
@@ -18,18 +18,18 @@ fn onMessage(
         connection.publish(reply, "salutations") catch @panic("HELP");
     }
 
-    userdata.* = true;
+    userdata.* += 1;
 }
 
 pub fn main() !void {
     const connection = try nats.Connection.connectTo(nats.default_server_url);
     defer connection.destroy();
 
-    var done = false;
-    const subscription = try connection.subscribe(bool, "channel", onMessage, &done);
+    var count: u32 = 0;
+    const subscription = try connection.subscribe(u32, "channel", onMessage, &count);
     defer subscription.destroy();
 
-    while (!done) {
+    while (count < 10) : (nats.sleep(1000)) {
         const reply = try connection.request("channel", "greetings", 1000);
         defer reply.destroy();
 

src/connection.zig

@@ -893,7 +893,7 @@ pub fn makeConnectionCallbackThunk(
     return struct {
         fn thunk(conn: ?*nats_c.natsConnection, userdata: ?*anyopaque) callconv(.C) void {
             const connection: *Connection = if (conn) |c| @ptrCast(c) else unreachable;
-            const data: *T = if (userdata) |u| @ptrCast(u) else unreachable;
+            const data: *T = if (userdata) |u| @alignCast(@ptrCast(u)) else unreachable;
             callback(connection, data);
         }
     }.thunk;
@@ -916,7 +916,7 @@ pub fn makeReconnectDelayCallbackThunk(
             userdata: ?*anyopaque,
         ) callconv(.C) i64 {
             const connection: *Connection = if (conn) |c| @ptrCast(c) else unreachable;
-            const data: *T = if (userdata) |u| @ptrCast(u) else unreachable;
+            const data: *T = if (userdata) |u| @alignCast(@ptrCast(u)) else unreachable;
             return callback(connection, attempts, data);
         }
     }.thunk;
@@ -946,7 +946,7 @@ pub fn makeErrorHandlerCallbackThunk(
         ) callconv(.C) void {
             const connection: *Connection = if (conn) |c| @ptrCast(c) else unreachable;
             const subscription: *Subscription = if (sub) |s| @ptrCast(s) else unreachable;
-            const data: *T = if (userdata) |u| @ptrCast(u) else unreachable;
+            const data: *T = if (userdata) |u| @alignCast(@ptrCast(u)) else unreachable;
 
             callback(connection, subscription, Status.fromInt(status), data);
         }
@@ -1005,7 +1005,7 @@ pub fn makeEventLoopAddRemoveCallbackThunk(
             userdata: ?*anyopaque,
         ) callconv(.C) nats_c.natsStatus {
             const connection: *Connection = if (conn) |c| @ptrCast(c) else unreachable;
-            const data: *T = if (userdata) |u| @ptrCast(u) else unreachable;
+            const data: *T = if (userdata) |u| @alignCast(@ptrCast(u)) else unreachable;
             callback(connection, attempts, data) catch |err|
                 return Status.fromError(err).toInt();
 
@@ -1028,7 +1028,7 @@ pub fn makeEventLoopDetachCallbackThunk(
         fn thunk(
             userdata: ?*anyopaque,
         ) callconv(.C) nats_c.natsStatus {
-            const data: *T = if (userdata) |u| @ptrCast(u) else unreachable;
+            const data: *T = if (userdata) |u| @alignCast(@ptrCast(u)) else unreachable;
             callback(data) catch |err| return Status.fromError(err).toInt();
             return nats_c.NATS_OK;
         }
@@ -1058,7 +1058,7 @@ pub fn makeJwtHandlerCallbackThunk(
             err_out: *?[*:0]u8,
             userdata: ?*anyopaque,
         ) callconv(.C) nats_c.natsStatus {
-            const data: *T = if (userdata) |u| @ptrCast(u) else unreachable;
+            const data: *T = if (userdata) |u| @alignCast(@ptrCast(u)) else unreachable;
 
             switch (callback(data)) {
                 .jwt => |jwt| {
@@ -1099,7 +1099,7 @@ pub fn makeSignatureHandlerCallbackThunk(
             nonce: [*:0]const u8,
             userdata: ?*anyopaque,
         ) callconv(.C) nats_c.natsStatus {
-            const data: *T = if (userdata) |u| @ptrCast(u) else unreachable;
+            const data: *T = if (userdata) |u| @alignCast(@ptrCast(u)) else unreachable;
 
             switch (callback(std.mem.sliceTo(nonce, 0), data)) {
                 .signature => |sig| {

src/subscription.zig

@@ -197,7 +197,7 @@ pub fn makeSubscriptionCallbackThunk(
             const connection: *Connection = if (conn) |c| @ptrCast(c) else unreachable;
             const subscription: *Subscription = if (sub) |s| @ptrCast(s) else unreachable;
 
-            const data: *T = if (userdata) |u| @ptrCast(u) else unreachable;
+            const data: *T = if (userdata) |u| @alignCast(@ptrCast(u)) else unreachable;
 
             callback(data, connection, subscription, message);
         }

src/thunk.zig

@@ -16,7 +16,7 @@ pub fn makeSimpleCallbackThunk(
 ) *const SimpleCallback {
     return struct {
         fn thunk(userdata: ?*anyopaque) callconv(.C) void {
-            const data: *T = if (userdata) |u| @ptrCast(u) else unreachable;
+            const data: *T = if (userdata) |u| @alignCast(@ptrCast(u)) else unreachable;
             callback(data);
         }
     }.thunk;