Fix Windows startup stack overflow (port of #10 by @chrislearn)

build.rs

@@ -0,0 +1,12 @@
+// Windows reserves only 1 MiB for the main thread by default. OctoSense's
+// startup evaluates and constructs a large Makepad script/widget tree on that
+// thread, whose bounded peak exceeds the default before the first window is
+// shown. /STACK changes the PE address-space reserve; pages are still committed
+// only as they are used.
+fn main() {
+    let target_os = std::env::var("CARGO_CFG_TARGET_OS").unwrap_or_default();
+    let target_env = std::env::var("CARGO_CFG_TARGET_ENV").unwrap_or_default();
+    if target_os == "windows" && target_env == "msvc" {
+        println!("cargo:rustc-link-arg-bins=/STACK:16777216");
+    }
+}

src/clients.rs

@@ -28,7 +28,10 @@ use crate::host;
 #[cfg(unix)]
 use std::os::unix::process::CommandExt;
 
-use makepad_widgets::makepad_platform::thread::{CancellationToken, Lane, SignalToUI, TaskPool, ThreadSpawner, ThreadOptions};
+#[cfg(unix)]
+use makepad_widgets::makepad_platform::thread::CancellationToken;
+use makepad_widgets::makepad_platform::thread::{Lane, SignalToUI, TaskPool, ThreadSpawner, ThreadOptions};
+#[cfg(any(unix, test))]
 use makepad_widgets::Cx;
 
 use crate::hub::ClientId;
@@ -643,7 +646,7 @@ pub fn kill_child_group(child: &mut Child, _grace: std::time::Duration, _pool: &
 /// Final slot teardown owns the child from here on. Signal and reap it wholly
 /// on a heavy pool worker; dropping a slot on the UI thread never waits for a
 /// process or decoder wrapper to exit.
-fn reap_child_group(mut child: Child, grace: std::time::Duration, pool: &TaskPool) {
+fn reap_child_group(mut child: Child, _grace: std::time::Duration, pool: &TaskPool) {
     #[cfg(unix)]
     let pid = {
         let pid = child.id() as i32;
@@ -656,7 +659,7 @@ fn reap_child_group(mut child: Child, grace: std::time::Duration, pool: &TaskPoo
                 #[cfg(unix)]
                 {
                     let wait = CancellationToken::new();
-                    let _ = wait.wait_until(Cx::monotonic_now() + grace.as_secs_f64());
+                    let _ = wait.wait_until(Cx::monotonic_now() + _grace.as_secs_f64());
                     if signal::alive(-pid) {
                         signal::kill_group(pid, signal::SIGKILL);
                     }