feat: Raw identifier support in object macro

This commit implements raw identifier (`r#name`) support
for field names (methods) and arguments in the `object` proc macro.

Eg:

```rust
impl T {
  fn r#type(r#trait: String) -> bool {}
}
```

integration_tests/juniper_tests/src/codegen/derive_object_with_raw_idents.rs

@@ -0,0 +1,105 @@
+#[cfg(test)]
+use fnv::FnvHashMap;
+#[cfg(test)]
+use juniper::Object;
+
+#[cfg(test)]
+use juniper::{
+    self, execute, graphql_value, DefaultScalarValue, EmptyMutation, GraphQLInputObject,
+    GraphQLType, RootNode, Value, Variables,
+};
+
+pub struct Query;
+
+#[juniper::object]
+impl Query {
+    fn r#type(r#fn: MyInputType) -> Vec<String> {
+        unimplemented!()
+    }
+}
+
+#[derive(GraphQLInputObject, Debug, PartialEq)]
+struct MyInputType {
+    r#trait: String,
+}
+
+#[test]
+fn supports_raw_idents_in_types_and_args() {
+    let doc = r#"
+    {
+        __type(name: "Query") {
+            fields {
+                name
+                args {
+                    name
+                }
+            }
+        }
+    }
+    "#;
+
+    let value = run_type_info_query(&doc);
+
+    assert_eq!(
+        value,
+        graphql_value!(
+            {
+                "__type": {
+                    "fields": [
+                        {
+                            "name": "type",
+                            "args": [
+                                {
+                                    "name": "fn"
+                                }
+                            ]
+                        }
+                    ]
+                }
+            }
+        ),
+    );
+}
+
+#[test]
+fn supports_raw_idents_in_fields_of_input_types() {
+    let doc = r#"
+    {
+        __type(name: "MyInputType") {
+            inputFields {
+              name
+            }
+        }
+    }
+    "#;
+
+    let value = run_type_info_query(&doc);
+
+    assert_eq!(
+        value,
+        graphql_value!(
+            {
+                "__type": {
+                    "inputFields": [
+                        {
+                            "name": "trait",
+                        }
+                    ]
+                }
+            }
+        ),
+    );
+}
+
+#[cfg(test)]
+fn run_type_info_query(doc: &str) -> Value {
+    let schema = RootNode::new(Query, EmptyMutation::<()>::new());
+
+    let (result, errs) =
+        execute(doc, None, &schema, &Variables::new(), &()).expect("Execution failed");
+
+    assert_eq!(errs, []);
+
+    println!("Result: {:#?}", result);
+    result
+}

integration_tests/juniper_tests/src/codegen/mod.rs

@@ -3,4 +3,5 @@ mod util;
 mod derive_enum;
 mod derive_input_object;
 mod derive_object;
+mod derive_object_with_raw_idents;
 mod scalar_value_transparent;

juniper/CHANGELOG.md

@@ -1,6 +1,6 @@
 # master
 
-- No changes yet
+- Correctly handle raw identifiers in field and argument names.
 
 # [[0.14.1] 2019-10-24](https://github.com/graphql-rust/juniper/releases/tag/juniper-0.14.1)
 

juniper_codegen/src/derive_input_object.rs

@@ -170,7 +170,7 @@ pub fn impl_input_object(ast: &syn::DeriveInput, is_internal: bool) -> TokenStre
             }
             None => {
                 // Note: auto camel casing when no custom name specified.
-                crate::util::to_camel_case(&field_ident.to_string())
+                crate::util::to_camel_case(&unraw(&field_ident.to_string()))
             }
         };
         let field_description = match field_attrs.description {

juniper_codegen/src/lib.rs

@@ -352,6 +352,24 @@ impl Query {
 }
 ```
 
+## Raw identifiers
+
+You can use [raw identifiers](https://doc.rust-lang.org/stable/edition-guide/rust-2018/module-system/raw-identifiers.html)
+if you want a GrahpQL field that happens to be a Rust keyword:
+
+```
+struct User {
+    r#type: String,
+}
+
+#[juniper::object]
+impl User {
+    fn r#type(&self) -> &str {
+        &self.r#type
+    }
+}
+```
+
 */
 #[proc_macro_attribute]
 pub fn object(args: TokenStream, input: TokenStream) -> TokenStream {

juniper_codegen/src/util.rs

@@ -593,6 +593,11 @@ pub struct GraphQLTypeDefinitionField {
     pub resolver_code: proc_macro2::TokenStream,
 }
 
+pub fn unraw(s: &str) -> String {
+    use syn::ext::IdentExt;
+    quote::format_ident!("{}", s).unraw().to_string()
+}
+
 /// Definition of a graphql type based on information extracted
 /// by various macros.
 /// The definition can be rendered to Rust code.
@@ -635,7 +640,7 @@ impl GraphQLTypeDefiniton {
         let field_definitions = self.fields.iter().map(|field| {
             let args = field.args.iter().map(|arg| {
                 let arg_type = &arg._type;
-                let arg_name = &arg.name;
+                let arg_name = unraw(&arg.name);
 
                 let description = match arg.description.as_ref() {
                     Some(value) => quote!( .description( #value ) ),
@@ -675,7 +680,7 @@ impl GraphQLTypeDefiniton {
                 None => quote!(),
             };
 
-            let field_name = &field.name;
+            let field_name = unraw(&field.name);
 
             let _type = &field._type;
             quote! {