From 4c01fee5c5018b41689a163166c8a8f1500420e8 Mon Sep 17 00:00:00 2001
From: Devin Ragotzy <devin.ragotzy@gmail.com>
Date: Tue, 28 Jul 2020 17:12:32 -0400
Subject: [PATCH] Move new type body init field (last field initialized)

---
 ruma-api-macros/src/api/request.rs  | 17 +++++++++++++++--
 ruma-api-macros/src/api/response.rs | 20 ++++++++++++++------
 2 files changed, 29 insertions(+), 8 deletions(-)

diff --git a/ruma-api-macros/src/api/request.rs b/ruma-api-macros/src/api/request.rs
index 95e3ef0c..0918849d 100644
--- a/ruma-api-macros/src/api/request.rs
+++ b/ruma-api-macros/src/api/request.rs
@@ -163,7 +163,7 @@ impl Request {
         request_field_kind: RequestFieldKind,
         src: TokenStream,
     ) -> TokenStream {
-        let fields = self.fields.iter().filter_map(|f| {
+        let process_field = |f: &RequestField| {
             f.field_of_kind(request_field_kind).map(|field| {
                 let field_name =
                     field.ident.as_ref().expect("expected field to have an identifier");
@@ -176,7 +176,20 @@ impl Request {
                     #field_name: #src.#field_name
                 }
             })
-        });
+        };
+
+        let mut fields = vec![];
+        let mut new_type_body = None;
+        for field in &self.fields {
+            if let RequestField::NewtypeRawBody(_) = field {
+                new_type_body = process_field(field);
+            } else {
+                fields.extend(process_field(field));
+            }
+        }
+
+        // Move field that consumes `request` to the end of the init list.
+        fields.extend(new_type_body);
 
         quote! { #(#fields,)* }
     }
diff --git a/ruma-api-macros/src/api/response.rs b/ruma-api-macros/src/api/response.rs
index 0d8d8283..3ff77f61 100644
--- a/ruma-api-macros/src/api/response.rs
+++ b/ruma-api-macros/src/api/response.rs
@@ -38,14 +38,16 @@ impl Response {
 
     /// Produces code for a response struct initializer.
     pub fn init_fields(&self) -> TokenStream {
-        let fields = self.fields.iter().map(|response_field| {
+        let mut fields = vec![];
+        let mut new_type_raw_body = None;
+        for response_field in &self.fields {
             let field = response_field.field();
             let field_name = field.ident.as_ref().expect("expected field to have an identifier");
             let span = field.span();
             let cfg_attrs =
                 field.attrs.iter().filter(|a| a.path.is_ident("cfg")).collect::<Vec<_>>();
 
-            match response_field {
+            fields.push(match response_field {
                 ResponseField::Body(_) => {
                     quote_spanned! {span=>
                         #( #cfg_attrs )*
@@ -66,13 +68,19 @@ impl Response {
                         #field_name: response_body.0
                     }
                 }
+                // This field must be instantiated last to avoid `use of move value` error.
+                // We are guaranteed only one new body field because of a check in `try_from`.
                 ResponseField::NewtypeRawBody(_) => {
-                    quote_spanned! {span=>
+                    new_type_raw_body = Some(quote_spanned! {span=>
                         #field_name: response.into_body()
-                    }
+                    });
+                    // skip adding to the vec
+                    continue;
                 }
-            }
-        });
+            });
+        }
+
+        fields.extend(new_type_raw_body);
 
         quote! {
             #(#fields,)*