fix modal exchange (#3620)

- Fix opening GoToLine from Command
- Extend test to cover go_to_line behavior too

Release Notes:

- N/A

crates/workspace2/src/modal_layer.rs

@@ -1,23 +1,23 @@
 use gpui::{
-    div, prelude::*, px, AnyView, Div, FocusHandle, ManagedView, Render, Subscription, Task, View,
-    ViewContext, WindowContext,
+    div, prelude::*, px, AnyView, DismissEvent, Div, FocusHandle, ManagedView, Render,
+    Subscription, View, ViewContext, WindowContext,
 };
 use ui::{h_stack, v_stack};
 
 pub trait ModalView: ManagedView {
-    fn dismiss(&mut self, cx: &mut ViewContext<Self>) -> Task<bool> {
-        Task::ready(true)
+    fn on_before_dismiss(&mut self, cx: &mut ViewContext<Self>) -> bool {
+        true
     }
 }
 
 trait ModalViewHandle {
-    fn should_dismiss(&mut self, cx: &mut WindowContext) -> Task<bool>;
+    fn on_before_dismiss(&mut self, cx: &mut WindowContext) -> bool;
     fn view(&self) -> AnyView;
 }
 
 impl<V: ModalView> ModalViewHandle for View<V> {
-    fn should_dismiss(&mut self, cx: &mut WindowContext) -> Task<bool> {
-        self.update(cx, |this, cx| this.dismiss(cx))
+    fn on_before_dismiss(&mut self, cx: &mut WindowContext) -> bool {
+        self.update(cx, |this, cx| this.on_before_dismiss(cx))
     }
 
     fn view(&self) -> AnyView {
@@ -48,8 +48,8 @@ impl ModalLayer {
     {
         if let Some(active_modal) = &self.active_modal {
             let is_close = active_modal.modal.view().downcast::<V>().is_ok();
-            self.hide_modal(cx);
-            if is_close {
+            let did_close = self.hide_modal(cx);
+            if is_close || !did_close {
                 return;
             }
         }
@@ -57,13 +57,15 @@ impl ModalLayer {
         self.show_modal(new_modal, cx);
     }
 
-    pub fn show_modal<V>(&mut self, new_modal: View<V>, cx: &mut ViewContext<Self>)
+    fn show_modal<V>(&mut self, new_modal: View<V>, cx: &mut ViewContext<Self>)
     where
         V: ModalView,
     {
         self.active_modal = Some(ActiveModal {
             modal: Box::new(new_modal.clone()),
-            subscription: cx.subscribe(&new_modal, |this, modal, e, cx| this.hide_modal(cx)),
+            subscription: cx.subscribe(&new_modal, |this, modal, _: &DismissEvent, cx| {
+                this.hide_modal(cx);
+            }),
             previous_focus_handle: cx.focused(),
             focus_handle: cx.focus_handle(),
         });
@@ -71,29 +73,25 @@ impl ModalLayer {
         cx.notify();
     }
 
-    pub fn hide_modal(&mut self, cx: &mut ViewContext<Self>) {
+    fn hide_modal(&mut self, cx: &mut ViewContext<Self>) -> bool {
         let Some(active_modal) = self.active_modal.as_mut() else {
-            return;
+            return false;
         };
 
-        let dismiss = active_modal.modal.should_dismiss(cx);
+        let dismiss = active_modal.modal.on_before_dismiss(cx);
+        if !dismiss {
+            return false;
+        }
 
-        cx.spawn(|this, mut cx| async move {
-            if dismiss.await {
-                this.update(&mut cx, |this, cx| {
-                    if let Some(active_modal) = this.active_modal.take() {
-                        if let Some(previous_focus) = active_modal.previous_focus_handle {
-                            if active_modal.focus_handle.contains_focused(cx) {
-                                previous_focus.focus(cx);
-                            }
-                        }
-                        cx.notify();
-                    }
-                })
-                .ok();
+        if let Some(active_modal) = self.active_modal.take() {
+            if let Some(previous_focus) = active_modal.previous_focus_handle {
+                if active_modal.focus_handle.contains_focused(cx) {
+                    previous_focus.focus(cx);
+                }
             }
-        })
-        .detach();
+            cx.notify();
+        }
+        true
     }
 
     pub fn active_modal<V>(&self) -> Option<View<V>>