Allow named parameters to be ignored.

codegen/src/decorators/route.rs

@@ -74,6 +74,7 @@ impl RouteGenerateExt for RouteParams {
         let name = arg.ident().expect("form param identifier").prepend(PARAM_PREFIX);
         let ty = strip_ty_lifetimes(arg.ty.clone());
         Some(quote_stmt!(ecx,
+            #[allow(non_snake_case)]
             let $name: $ty = {
                 let mut items = ::rocket::request::FormItems::from($form_string);
                 let form = ::rocket::request::FromForm::from_form(items.by_ref(), true);
@@ -107,6 +108,7 @@ impl RouteGenerateExt for RouteParams {
         let name = arg.ident().expect("form param identifier").prepend(PARAM_PREFIX);
         let ty = strip_ty_lifetimes(arg.ty.clone());
         Some(quote_stmt!(ecx,
+            #[allow(non_snake_case, unreachable_patterns)]
             let $name: $ty =
                 match ::rocket::data::FromData::from_data(__req, __data) {
                     ::rocket::Outcome::Success(d) => d,
@@ -163,7 +165,7 @@ impl RouteGenerateExt for RouteParams {
 
             let original_ident = param.ident();
             fn_param_statements.push(quote_stmt!(ecx,
-                #[allow(unreachable_patterns)]
+                #[allow(non_snake_case, unreachable_patterns)]
                 let $ident: $ty = match $expr {
                     Ok(v) => v,
                     Err(e) => {
@@ -196,7 +198,7 @@ impl RouteGenerateExt for RouteParams {
             let ident = arg.ident().unwrap().prepend(PARAM_PREFIX);
             let ty = strip_ty_lifetimes(arg.ty.clone());
             fn_param_statements.push(quote_stmt!(ecx,
-                #[allow(non_snake_case)]
+                #[allow(non_snake_case, unreachable_patterns)]
                 let $ident: $ty = match
                         ::rocket::request::FromRequest::from_request(__req) {
                     ::rocket::Outcome::Success(v) => v,

codegen/src/parser/uri.rs

@@ -60,9 +60,9 @@ fn valid_segments(ecx: &ExtCtxt, uri: &URI, sp: Span) -> bool {
                 ecx.struct_span_err(span, "parameter names must be valid identifiers")
                     .note(&format!("{:?} is not a valid identifier", param))
                     .emit();
-            } else if param.starts_with('_') {
+            } else if param == "_" {
-                ecx.struct_span_err(span, "parameters cannot be ignored")
+                ecx.struct_span_err(span, "parameters must be named")
-                    .note(&format!("{:?} is being ignored", param))
+                    .help("use a name such as `_guard` or `_param`")
                     .emit();
             } else {
                 continue

codegen/tests/compile-fail/ignored_params.rs

@@ -10,4 +10,7 @@ fn get1() -> &'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
 
+#[get("/<_r>")] //~ ERROR '_r' is declared
+fn get2(r: usize) -> &'static str { "hi" } //~ ERROR isn't in the function
+
 fn main() {  }

codegen/tests/compile-fail/malformed-param-list.rs

@@ -13,7 +13,7 @@ fn get2(id: usize) -> &'static str { "hi" }
 #[get("/<!>")] //~ ERROR identifiers
 fn get3() -> &'static str { "hi" }
 
-#[get("/<_>")] //~ ERROR ignored
+#[get("/<_>")] //~ ERROR named
 fn get4() -> &'static str { "hi" }
 
 #[get("/<1>")] //~ ERROR identifiers

codegen/tests/run-pass/complete-decorator.rs

@@ -12,9 +12,9 @@ struct User<'a> {
     nickname: String,
 }
 
-#[post("/<name>?<query>", format = "application/json", data = "<user>", rank = 2)]
+#[post("/<name>?<_query>", format = "application/json", data = "<user>", rank = 2)]
 fn get<'r>(name: &RawStr,
-           query: User<'r>,
+           _query: User<'r>,
            user: Form<'r, User<'r>>,
            cookies: Cookies)
            -> &'static str {

codegen/tests/run-pass/dynamic-paths.rs

@@ -6,6 +6,9 @@ extern crate rocket;
 #[get("/test/<one>/<two>/<three>")]
 fn get(one: String, two: usize, three: isize) -> &'static str { "hi" }
 
+#[get("/test/<_one>/<_two>/<__three>")]
+fn ignored(_one: String, _two: usize, __three: isize) -> &'static str { "hi" }
+
 fn main() {
-    let _ = routes![get];
+    let _ = routes![get, ignored];
 }