Debugger template: allow missing or empty completion list (#10332)

It can be convenient to define project specific debugger templates, some of
which might not necessitate prompting the user to define completion.

This commit makes completion optional for debugger templates and starts the
dap immediately if undefined or empty.

helix-core/src/syntax.rs

@@ -510,6 +510,7 @@ pub enum DebugArgumentValue {
 pub struct DebugTemplate {
     pub name: String,
     pub request: String,
+    #[serde(default)]
     pub completion: Vec<DebugConfigCompletion>,
     pub args: HashMap<String, DebugArgumentValue>,
 }

helix-term/src/commands/dap.rs

@@ -172,9 +172,9 @@ pub fn dap_start_impl(
 
     let mut args: HashMap<&str, Value> = HashMap::new();
 
-    if let Some(params) = params {
     for (k, t) in &template.args {
         let mut value = t.clone();
+        if let Some(ref params) = params {
             for (i, x) in params.iter().enumerate() {
                 let mut param = x.to_string();
                 if let Some(DebugConfigCompletion::Advanced(cfg)) = template.completion.get(i) {
@@ -198,6 +198,7 @@ pub fn dap_start_impl(
                     DebugArgumentValue::Boolean(_) => value,
                 };
             }
+        }
 
         match value {
             DebugArgumentValue::String(string) => {
@@ -215,7 +216,6 @@ pub fn dap_start_impl(
             }
         }
     }
-    }
 
     args.insert("cwd", to_value(helix_stdx::env::current_working_dir())?);
 
@@ -272,6 +272,11 @@ pub fn dap_launch(cx: &mut Context) {
         templates,
         (),
         |cx, template, _action| {
+            if template.completion.is_empty() {
+                if let Err(err) = dap_start_impl(cx, Some(&template.name), None, None) {
+                    cx.editor.set_error(err.to_string());
+                }
+            } else {
                 let completions = template.completion.clone();
                 let name = template.name.clone();
                 let callback = Box::pin(async move {
@@ -283,6 +288,7 @@ pub fn dap_launch(cx: &mut Context) {
                     Ok(call)
                 });
                 cx.jobs.callback(callback);
+            }
         },
     ))));
 }