debugger: Allow users to include PickProcessId in debug tasks and resolve Pid (#42913)

Closes #33286

This PR adds support for Zed's `$ZED_PICK_PID` command in debug
configurations, which allows users to select a process to attach to at
debug time. When this variable is present in a debug configuration, Zed
automatically opens a process picker modal.

Follow up for this will be integrating this variable in the task system
instead of just the debug configuration system.

Release Notes:

- Added `$ZED_PICK_PID` variable for debug configurations, allowing
users to select which process to attach the debugger to at runtime

---------

Co-authored-by: Remco Smits <djsmits12@gmail.com>

crates/debugger_ui/src/session/running.rs

@@ -5,16 +5,23 @@ pub(crate) mod memory_view;
 pub(crate) mod module_list;
 pub mod stack_frame_list;
 pub mod variable_list;
-use std::{any::Any, ops::ControlFlow, path::PathBuf, sync::Arc, time::Duration};
+use std::{
+    any::Any,
+    ops::ControlFlow,
+    path::PathBuf,
+    sync::{Arc, LazyLock},
+    time::Duration,
+};
 
 use crate::{
     ToggleExpandItem,
+    attach_modal::{AttachModal, ModalIntent},
     new_process_modal::resolve_path,
     persistence::{self, DebuggerPaneItem, SerializedLayout},
     session::running::memory_view::MemoryView,
 };
 
-use anyhow::{Context as _, Result, anyhow};
+use anyhow::{Context as _, Result, anyhow, bail};
 use breakpoint_list::BreakpointList;
 use collections::{HashMap, IndexMap};
 use console::Console;
@@ -56,6 +63,9 @@ use workspace::{
     Workspace, item::TabContentParams, move_item, pane::Event,
 };
 
+static PROCESS_ID_PLACEHOLDER: LazyLock<String> =
+    LazyLock::new(|| task::VariableName::PickProcessId.template_value());
+
 pub struct RunningState {
     session: Entity<Session>,
     thread_id: Option<ThreadId>,
@@ -653,6 +663,40 @@ impl RunningState {
         }
     }
 
+    pub(crate) fn contains_substring(config: &serde_json::Value, substring: &str) -> bool {
+        match config {
+            serde_json::Value::Object(obj) => obj
+                .values()
+                .any(|value| Self::contains_substring(value, substring)),
+            serde_json::Value::Array(array) => array
+                .iter()
+                .any(|value| Self::contains_substring(value, substring)),
+            serde_json::Value::String(s) => s.contains(substring),
+            _ => false,
+        }
+    }
+
+    pub(crate) fn substitute_process_id_in_config(config: &mut serde_json::Value, process_id: i32) {
+        match config {
+            serde_json::Value::Object(obj) => {
+                obj.values_mut().for_each(|value| {
+                    Self::substitute_process_id_in_config(value, process_id);
+                });
+            }
+            serde_json::Value::Array(array) => {
+                array.iter_mut().for_each(|value| {
+                    Self::substitute_process_id_in_config(value, process_id);
+                });
+            }
+            serde_json::Value::String(s) => {
+                if s.contains(PROCESS_ID_PLACEHOLDER.as_str()) {
+                    *s = s.replace(PROCESS_ID_PLACEHOLDER.as_str(), &process_id.to_string());
+                }
+            }
+            _ => {}
+        }
+    }
+
     pub(crate) fn relativize_paths(
         key: Option<&str>,
         config: &mut serde_json::Value,
@@ -955,6 +999,31 @@ impl RunningState {
             Self::relativize_paths(None, &mut config, &task_context);
             Self::substitute_variables_in_config(&mut config, &task_context);
 
+            if Self::contains_substring(&config, PROCESS_ID_PLACEHOLDER.as_str()) || label.as_ref().contains(PROCESS_ID_PLACEHOLDER.as_str()) {
+                let (tx, rx) = futures::channel::oneshot::channel::<Option<i32>>();
+
+                let weak_workspace_clone = weak_workspace.clone();
+                weak_workspace.update_in(cx, |workspace, window, cx| {
+                    let project = workspace.project().clone();
+                    workspace.toggle_modal(window, cx, |window, cx| {
+                        AttachModal::new(
+                            ModalIntent::ResolveProcessId(Some(tx)),
+                            weak_workspace_clone,
+                            project,
+                            true,
+                            window,
+                            cx,
+                        )
+                    });
+                }).ok();
+
+                let Some(process_id) = rx.await.ok().flatten() else {
+                    bail!("No process selected with config that contains {}", PROCESS_ID_PLACEHOLDER.as_str())
+                };
+
+                Self::substitute_process_id_in_config(&mut config, process_id);
+            }
+
             let request_type = match dap_registry
                 .adapter(&adapter)
                 .with_context(|| format!("{}: is not a valid adapter name", &adapter)) {