Make route collisions a hard error.

This is a breaking change. Previously, route collisions were warnings.

examples/errors/src/main.rs

@@ -21,6 +21,7 @@ fn not_found(req: &rocket::Request) -> content::HTML<String> {
 
 fn main() {
     let e = rocket::ignite()
+        // .mount("/", routes![hello, hello]) // uncoment this to get an error
         .mount("/", routes![hello])
         .catch(errors![not_found])
         .launch();

lib/src/error.rs

@@ -23,11 +23,14 @@ pub enum Error {
 /// The kind of launch error that occured.
 ///
 /// In almost every instance, a launch error occurs because of an I/O error;
-/// this represented by the `Io` variant. The `Unknown` variant captures all
-/// other kinds of launch errors.
+/// this is represented by the `Io` variant. A launch error may also occur
+/// because of ill-defined routes that lead to collisions; this is represented
+/// by the `Collision` variant. The `Unknown` variant captures all other kinds
+/// of launch errors.
 #[derive(Debug)]
 pub enum LaunchErrorKind {
     Io(io::Error),
+    Collision,
     Unknown(Box<::std::error::Error + Send + Sync>)
 }
 
@@ -110,6 +113,13 @@ impl LaunchError {
     }
 }
 
+impl From<LaunchErrorKind> for LaunchError {
+    #[inline]
+    fn from(kind: LaunchErrorKind) -> LaunchError {
+        LaunchError::new(kind)
+    }
+}
+
 impl From<hyper::Error> for LaunchError {
     #[inline]
     fn from(error: hyper::Error) -> LaunchError {
@@ -125,6 +135,7 @@ impl fmt::Display for LaunchErrorKind {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         match *self {
             LaunchErrorKind::Io(ref e) => write!(f, "I/O error: {}", e),
+            LaunchErrorKind::Collision => write!(f, "route collisions detected"),
             LaunchErrorKind::Unknown(ref e) => write!(f, "unknown error: {}", e)
         }
     }
@@ -152,6 +163,7 @@ impl ::std::error::Error for LaunchError {
         self.mark_handled();
         match *self.kind() {
             LaunchErrorKind::Io(_) => "an I/O error occured during launch",
+            LaunchErrorKind::Collision => "route collisions were detected",
             LaunchErrorKind::Unknown(_) => "an unknown error occured during launch"
         }
     }
@@ -168,6 +180,10 @@ impl Drop for LaunchError {
                 error!("Rocket failed to launch due to an I/O error.");
                 panic!("{}", e);
             }
+            LaunchErrorKind::Collision => {
+                error!("Rocket failed to launch due to routing collisions.");
+                panic!("route collisions detected");
+            }
             LaunchErrorKind::Unknown(ref e) => {
                 error!("Rocket failed to launch due to an unknown error.");
                 panic!("{}", e);

lib/src/rocket.rs

@@ -18,7 +18,7 @@ use response::{Body, Response};
 use router::{Router, Route};
 use catcher::{self, Catcher};
 use outcome::Outcome;
-use error::{Error, LaunchError};
+use error::{Error, LaunchError, LaunchErrorKind};
 
 use http::{Method, Status, Header, Session};
 use http::hyper::{self, header};
@@ -596,7 +596,7 @@ impl Rocket {
     /// ```
     pub fn launch(self) -> LaunchError {
         if self.router.has_collisions() {
-            warn!("Route collisions detected!");
+            return LaunchError::from(LaunchErrorKind::Collision);
         }
 
         let full_addr = format!("{}:{}", self.config.address, self.config.port);

lib/src/router/mod.rs

@@ -51,7 +51,7 @@ impl Router {
                 for b_route in routes.iter().skip(i + 1) {
                     if a_route.collides_with(b_route) {
                         result = true;
-                        warn!("{} and {} collide!", a_route, b_route);
+                        error!("{} and {} collide!", a_route, b_route);
                     }
                 }
             }