Port over doc comments in route macros. (#2022)

Co-authored-by: Jonas Platte <jplatte@users.noreply.github.com>
Co-authored-by: Rob Ede <robjtede@icloud.com>

actix-web-codegen/CHANGES.md

@@ -1,6 +1,9 @@
 # Changes
 
 ## Unreleased - 2021-xx-xx
+* Preserve doc comments when using route macros. [#2022]
+
+[#2022]: https://github.com/actix/actix-web/pull/2022
 
 
 ## 0.5.0-beta.1 - 2021-02-10

actix-web-codegen/src/route.rs

@@ -176,6 +176,9 @@ pub struct Route {
     args: Args,
     ast: syn::ItemFn,
     resource_type: ResourceType,
+
+    /// The doc comment attributes to copy to generated struct, if any.
+    doc_attributes: Vec<syn::Attribute>,
 }
 
 fn guess_resource_type(typ: &syn::Type) -> ResourceType {
@@ -221,6 +224,18 @@ impl Route {
         let ast: syn::ItemFn = syn::parse(input)?;
         let name = ast.sig.ident.clone();
 
+        // Try and pull out the doc comments so that we can reapply them to the
+        // generated struct.
+        //
+        // Note that multi line doc comments are converted to multiple doc
+        // attributes.
+        let doc_attributes = ast
+            .attrs
+            .iter()
+            .filter(|attr| attr.path.is_ident("doc"))
+            .cloned()
+            .collect();
+
         let args = Args::new(args, method)?;
         if args.methods.is_empty() {
             return Err(syn::Error::new(
@@ -248,6 +263,7 @@ impl Route {
             args,
             ast,
             resource_type,
+            doc_attributes,
         })
     }
 }
@@ -265,6 +281,7 @@ impl ToTokens for Route {
                     methods,
                 },
             resource_type,
+            doc_attributes,
         } = self;
         let resource_name = name.to_string();
         let method_guards = {
@@ -287,6 +304,7 @@ impl ToTokens for Route {
         };
 
         let stream = quote! {
+            #(#doc_attributes)*
             #[allow(non_camel_case_types, missing_docs)]
             pub struct #name;
 

actix-web-codegen/tests/trybuild.rs

@@ -9,6 +9,8 @@ fn compile_macros() {
     t.compile_fail("tests/trybuild/route-missing-method-fail.rs");
     t.compile_fail("tests/trybuild/route-duplicate-method-fail.rs");
     t.compile_fail("tests/trybuild/route-unexpected-method-fail.rs");
+
+    t.pass("tests/trybuild/docstring-ok.rs");
 }
 
 // #[rustversion::not(nightly)]

actix-web-codegen/tests/trybuild/docstring-ok.rs

@@ -0,0 +1,17 @@
+use actix_web::{Responder, HttpResponse, App, test};
+use actix_web_codegen::*;
+
+/// Docstrings shouldn't break anything.
+#[get("/")]
+async fn index() -> impl Responder {
+    HttpResponse::Ok()
+}
+
+#[actix_web::main]
+async fn main() {
+    let srv = test::start(|| App::new().service(index));
+
+    let request = srv.get("/");
+    let response = request.send().await.unwrap();
+    assert!(response.status().is_success());
+}