Allow services with no name

src/main.rs

@@ -45,7 +45,7 @@ struct PortRegistration {
     job: String,
     group: String,
     task: String,
-    service: String,
+    service: Option<String>,
 }
 
 impl Ctx {
@@ -139,7 +139,11 @@ fn main() -> Result<ExitCode> {
             println!("Conflict in site {}, port {:?}:", &datacenter, port);
             for reg in &regs {
                 println!("- in {}, job \"{}\", group \"{}\", task \"{}\", service \"{}\"",
-                         reg.file.display(), reg.job, reg.group, reg.task, reg.service)
+                         reg.file.display(), reg.job, reg.group, reg.task,
+                         match &reg.service {
+                             None => "<noname>",
+                             Some(s) => s
+                         })
             }
             println!()
         }

src/parsing.rs

@@ -28,7 +28,7 @@ pub struct Task {
 
 #[derive(Deserialize, Debug)]
 pub struct Service {
-    pub name: String,
+    pub name: Option<String>,
     pub tags: Vec<String>,
 }
 
@@ -66,7 +66,9 @@ impl Task {
 
 impl Service {
     fn from_body(b: &Body) -> Result<Self, String> {
-        let name = string_from_expr(&attribute_from_body(b, "name")?)?;
+        let name =
+            attribute_from_body(b, "name").ok()
+            .map(|e| string_from_expr(&e)).transpose()?;
         let tags = match attribute_from_body(b, "tags") {
             Err(_) => Vec::new(),
             Ok(tags) => tags_from_expr(&tags)?,