Allow 'non_snake_case' for generated query params.

Also adds '#[deny(non_snake_case)]' to the complete route generation
test for regressions.

Fixes #1003.

core/codegen/src/attribute/route.rs

@@ -220,9 +220,11 @@ fn query_exprs(route: &Route) -> Option<TokenStream2> {
 
         let decl = match segment.kind {
             Kind::Single => quote_spanned! { span =>
+                #[allow(non_snake_case)]
                 let mut #ident: Option<#ty> = None;
             },
             Kind::Multi => quote_spanned! { span =>
+                #[allow(non_snake_case)]
                 let mut #trail = #SmallVec::<[#request::FormItem; 8]>::new();
             },
             Kind::Static => quote!()
@@ -253,6 +255,7 @@ fn query_exprs(route: &Route) -> Option<TokenStream2> {
 
         let builder = match segment.kind {
             Kind::Single => quote_spanned! { span =>
+                #[allow(non_snake_case)]
                 let #ident = match #ident.or_else(<#ty as #request::FromFormValue>::default) {
                     Some(__v) => __v,
                     None => {
@@ -262,6 +265,7 @@ fn query_exprs(route: &Route) -> Option<TokenStream2> {
                 };
             },
             Kind::Multi => quote_spanned! { span =>
+                #[allow(non_snake_case)]
                 let #ident = match <#ty as #request::FromQuery>::from_query(#Query(&#trail)) {
                     Ok(__v) => __v,
                     Err(__e) => {

core/codegen/tests/route.rs

@@ -1,5 +1,10 @@
 #![feature(proc_macro_hygiene, decl_macro)]
 
+// Rocket sometimes generates mangled identifiers that activate the
+// non_snake_case lint. We deny the lint in this test to ensure that
+// code generation uses #[allow(non_snake_case)] in the appropriate places.
+#![deny(non_snake_case)]
+
 #[macro_use] extern crate rocket;
 
 use std::path::PathBuf;
@@ -65,6 +70,10 @@ fn post2(
     format!("({}) ({})", string, uri.to_string())
 }
 
+#[post("/<_unused_param>?<_unused_query>", data="<_unused_data>")]
+fn test_unused_params(_unused_param: String, _unused_query: String, _unused_data: Data) {
+}
+
 #[test]
 fn test_full_route() {
     let rocket = rocket::ignite()