clidispatch: punch "@prog@" variables in abort messages

Summary: This way you can use "prog@" more conviently when bailing out with an error that gives advice on what command to run.

Reviewed By: sggutier

Differential Revision: D50570658

fbshipit-source-id: 87b2bfe4e01a0a219df89d8bc29fbc0ddad49af6

eden/scm/lib/clidispatch/src/errors.rs

@@ -45,10 +45,17 @@ pub struct RepoRequired(pub String);
 #[error("malformed --config option: '{0}' (use --config section.name=value)")]
 pub struct MalformedConfigOption(pub String);
 
-#[derive(Debug, Error)]
-#[error("{0}")]
+#[derive(Debug)]
 pub struct Abort(pub Cow<'static, str>);
 
+impl std::error::Error for Abort {}
+
+impl std::fmt::Display for Abort {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "{}", identity::default().punch(&self.0))
+    }
+}
+
 /// Print an error suitable for end-user consumption.
 ///
 /// This function adds `hg:` or `abort:` to error messages.

eden/scm/lib/hgcommands/src/commands/goto.rs

@@ -7,6 +7,7 @@
 
 use anyhow::bail;
 use anyhow::Result;
+use clidispatch::abort;
 use clidispatch::fallback;
 use clidispatch::ReqCtx;
 use cliparser::define_flags;
@@ -85,9 +86,7 @@ pub fn run(ctx: ReqCtx<GotoOpts>, repo: &mut Repo, wc: &mut WorkingCopy) -> Resu
     }
 
     if dest.is_empty() {
-        bail!(identity::default().punch(
-            r#"You must specify a destination to update to, for example "@prog@ goto main"."#,
-        ));
+        abort!(r#"You must specify a destination to update to, for example "@prog@ goto main"."#);
     }
     if dest.len() > 1 {
         bail!(