fix(windows): clone HSTRING so it is not dropped eagerly

[amrbashir]

ref: https://discord.com/channels/616186924390023171/1229300159607996437/1229300159607996437

closes tauri-apps/tauri#9501

[CrendKing]

As you mentioned in tauri-apps/tauri#9501, I think you are right that since HString is a ref-counted structure, and PCWSTR is just a pointer and doesn't hold any actual data, the Option<HSTRING> needs to be moved into the closure.

A nitpick for the change: instead of cloning the Option, why not data_directory.as_ref().map(|d| PCWSTR::from_raw(d.as_ptr())) inside the closure? This way 1) the Option is moved in; 2) .as_ref() makes sure it's not dropped prematurely until the end of the closure; 3) cheaper than cloning.

diff --git a/src/webview2/mod.rs b/src/webview2/mod.rs
index 32dd2e2..e0954ac 100644
--- a/src/webview2/mod.rs
+++ b/src/webview2/mod.rs
@@ -248,7 +248,7 @@ impl InnerWebView {
       .as_deref()
       .and_then(|context| context.data_directory())
       .and_then(|path| path.to_str())
-      .map(String::from);
+      .map(HSTRING::from);

     // additional browser args
     let additional_browser_args = pl_attrs.additional_browser_args.unwrap_or_else(|| {
@@ -283,9 +283,6 @@ impl InnerWebView {
     let additional_browser_args = HSTRING::from(additional_browser_args);
     let additional_browser_args = PCWSTR::from_raw(additional_browser_args.as_ptr());

-    let data_directory = data_directory.map(HSTRING::from);
-    let data_directory = data_directory.map(|d| PCWSTR::from_raw(d.as_ptr()));
-
     let (tx, rx) = mpsc::channel();
     CreateCoreWebView2EnvironmentCompletedHandler::wait_for_async_operation(
       Box::new(move |environmentcreatedhandler| unsafe {
@@ -304,9 +301,11 @@ impl InnerWebView {
         );
         options.SetLanguage(PCWSTR::from_raw(lang.as_ptr()))?;

+        let data_directory_param = data_directory.as_ref().map(|d| PCWSTR::from_raw(d.as_ptr()));
+
         CreateCoreWebView2EnvironmentWithOptions(
           PCWSTR::null(),
-          data_directory.unwrap_or_else(PCWSTR::null),
+          data_directory_param.unwrap_or_else(PCWSTR::null),
           &options,
           &environmentcreatedhandler,
         )

[amrbashir]

thanks, that is better, pushed the change