Disallow use of data parameter with non-payload methods.

codegen/src/parser/route.rs

@@ -104,6 +104,16 @@ impl RouteParams {
             }
         }
 
+        // Sanity check: `data` should only be used with payload methods.
+        if let Some(ref data_param) = data {
+            if !method.node.supports_payload() {
+                ecx.struct_span_err(data_param.span, "`data` route parameters \
+                        can only be used with payload supporting methods")
+                    .note(&format!("'{}' does not support payloads", method.node))
+                    .emit();
+            }
+        }
+
         RouteParams {
             method: method,
             path: path,

codegen/tests/compile-fail/data-without-post.rs

@@ -0,0 +1,12 @@
+#![feature(plugin)]
+#![plugin(rocket_codegen)]
+
+extern crate rocket;
+
+use rocket::Data;
+
+#[get("/", data = "<something>")]
+//~^ ERROR payload supporting methods
+fn get(something: Data) -> &'static str { "hi" }
+
+fn main() {  }

codegen/tests/compile-fail/ignored_params.rs

@@ -7,7 +7,7 @@ fn get(other: &str) -> &'static str { "hi" } //~ ERROR isn't in the function
 #[get("/a?<r>")] //~ ERROR 'r' is declared
 fn get1() -> &'static str { "hi" } //~ ERROR isn't in the function
 
-#[get("/a", data = "<test>")] //~ ERROR 'test' is declared
-fn get2() -> &'static str { "hi" } //~ ERROR isn't in the function
+#[post("/a", data = "<test>")] //~ ERROR 'test' is declared
+fn post() -> &'static str { "hi" } //~ ERROR isn't in the function
 
 fn main() {  }

lib/src/response/responder.rs

@@ -7,9 +7,9 @@ use http::hyper::{header, FreshHyperResponse, StatusCode};
 use outcome::{self, IntoOutcome};
 use outcome::Outcome::*;
 
+/// Type alias for the `Outcome` of a `Responder`.
 pub type Outcome<'a> = outcome::Outcome<(), (), (StatusCode, FreshHyperResponse<'a>)>;
 
-
 impl<'a, T, E> IntoOutcome<(), (), (StatusCode, FreshHyperResponse<'a>)> for Result<T, E> {
     fn into_outcome(self) -> Outcome<'a> {
         match self {