Make axum-debug handle more cases (#518)

* Make `axum-debug` handle more cases

* Only just trybuild tests on stable

* revert changes to hello-world example

* Remove a bit of duplication

* return error on generics

* address review feedback

* Support associated functions with receiver or returns `Self`

* fix indentation

axum-debug/tests/fail/argument_not_extractor.stderr

@@ -4,8 +4,4 @@ error[E0277]: the trait bound `bool: FromRequest` is not satisfied
 4 | async fn handler(foo: bool) {}
   |                       ^^^^ the trait `FromRequest` is not implemented for `bool`
   |
-note: required by a bound in `handler::{closure#0}::debug_handler`
- --> tests/fail/argument_not_extractor.rs:4:23
-  |
-4 | async fn handler(foo: bool) {}
-  |                       ^^^^ required by this bound in `handler::{closure#0}::debug_handler`
+  = help: see issue #48214

axum-debug/tests/fail/attrs.rs

@@ -0,0 +1,6 @@
+use axum_debug::debug_handler;
+
+#[debug_handler(foo)]
+async fn handler() {}
+
+fn main() {}

axum-debug/tests/fail/attrs.stderr

@@ -0,0 +1,5 @@
+error: unexpected token
+ --> tests/fail/attrs.rs:3:17
+  |
+3 | #[debug_handler(foo)]
+  |                 ^^^

axum-debug/tests/fail/extract_self_mut.rs

@@ -0,0 +1,23 @@
+use axum::{
+    async_trait,
+    extract::{FromRequest, RequestParts},
+};
+use axum_debug::debug_handler;
+
+struct A;
+
+#[async_trait]
+impl FromRequest for A {
+    type Rejection = ();
+
+    async fn from_request(_req: &mut RequestParts) -> Result<Self, Self::Rejection> {
+        unimplemented!()
+    }
+}
+
+impl A {
+    #[debug_handler]
+    async fn handler(&mut self) {}
+}
+
+fn main() {}

axum-debug/tests/fail/extract_self_mut.stderr

@@ -0,0 +1,5 @@
+error: Handlers must only take owned values
+  --> tests/fail/extract_self_mut.rs:20:22
+   |
+20 |     async fn handler(&mut self) {}
+   |                      ^^^^^^^^^

axum-debug/tests/fail/extract_self_ref.rs

@@ -0,0 +1,23 @@
+use axum::{
+    async_trait,
+    extract::{FromRequest, RequestParts},
+};
+use axum_debug::debug_handler;
+
+struct A;
+
+#[async_trait]
+impl FromRequest for A {
+    type Rejection = ();
+
+    async fn from_request(_req: &mut RequestParts) -> Result<Self, Self::Rejection> {
+        unimplemented!()
+    }
+}
+
+impl A {
+    #[debug_handler]
+    async fn handler(&self) {}
+}
+
+fn main() {}

axum-debug/tests/fail/extract_self_ref.stderr

@@ -0,0 +1,5 @@
+error: Handlers must only take owned values
+  --> tests/fail/extract_self_ref.rs:20:22
+   |
+20 |     async fn handler(&self) {}
+   |                      ^^^^^

axum-debug/tests/fail/generics.rs

@@ -0,0 +1,6 @@
+use axum_debug::debug_handler;
+
+#[debug_handler]
+async fn handler<T>() {}
+
+fn main() {}

axum-debug/tests/fail/generics.stderr

@@ -0,0 +1,13 @@
+error: `#[axum_debug::debug_handler]` doesn't support generic functions
+ --> tests/fail/generics.rs:4:17
+  |
+4 | async fn handler<T>() {}
+  |                 ^^^
+
+error[E0282]: type annotations needed
+ --> tests/fail/generics.rs:4:10
+  |
+4 | async fn handler<T>() {}
+  | -----    ^^^^^^^ cannot infer type for type parameter `T` declared on the function `handler`
+  | |
+  | consider giving `future` a type

axum-debug/tests/fail/not_async.stderr

@@ -1,4 +1,4 @@
-error: handlers must be async functions
+error: Handlers must be `async fn`s
  --> tests/fail/not_async.rs:4:1
   |
 4 | fn handler() {}

axum-debug/tests/fail/not_send.stderr

@@ -1,8 +1,8 @@
 error: future cannot be sent between threads safely
- --> tests/fail/not_send.rs:4:10
+ --> tests/fail/not_send.rs:4:1
   |
 4 | async fn handler() {
-  |          ^^^^^^^ future returned by `handler` is not `Send`
+  | ^^^^^ future returned by `handler` is not `Send`
   |
   = help: within `impl Future`, the trait `Send` is not implemented for `Rc<()>`
 note: future is not `Send` as this value is used across an await
@@ -14,8 +14,8 @@ note: future is not `Send` as this value is used across an await
   |     ^^^^^^^^^^^^^^ await occurs here, with `rc` maybe used later
 7 | }
   | - `rc` is later dropped here
-note: required by a bound in `handler::{closure#0}::debug_handler`
- --> tests/fail/not_send.rs:4:10
+note: required by a bound in `check`
+ --> tests/fail/not_send.rs:4:1
   |
 4 | async fn handler() {
-  |          ^^^^^^^ required by this bound in `handler::{closure#0}::debug_handler`
+  | ^^^^^ required by this bound in `check`

axum-debug/tests/fail/self_receiver.stderr

@@ -1,5 +0,0 @@
-error: `#[debug_handler]` is not supported on methods
-  --> tests/fail/self_receiver.rs:17:22
-   |
-17 |     async fn handler(self) {}
-   |                      ^^^^

axum-debug/tests/fail/too_many_extractors.stderr

@@ -1,5 +1,4 @@
-error: too many extractors. 16 extractors are allowed
-note: you can nest extractors like "a: (Extractor, Extractor), b: (Extractor, Extractor)"
+error: Handlers cannot take more than 16 arguments. Use `(a, b): (ExtractorA, ExtractorA)` to further nest extractors
   --> tests/fail/too_many_extractors.rs:5:5
    |
 5  | /     e1: String,

axum-debug/tests/fail/wrong_return_type.stderr

@@ -4,8 +4,8 @@ error[E0277]: the trait bound `bool: IntoResponse` is not satisfied
 4 | async fn handler() -> bool {
   |                       ^^^^ the trait `IntoResponse` is not implemented for `bool`
   |
-note: required by a bound in `handler::{closure#0}::debug_handler`
+note: required by a bound in `__axum_debug_check_handler_into_response::{closure#0}::check`
  --> tests/fail/wrong_return_type.rs:4:23
   |
 4 | async fn handler() -> bool {
-  |                       ^^^^ required by this bound in `handler::{closure#0}::debug_handler`
+  |                       ^^^^ required by this bound in `__axum_debug_check_handler_into_response::{closure#0}::check`

axum-debug/tests/pass/associated_fn_without_self.rs

@@ -0,0 +1,10 @@
+use axum_debug::debug_handler;
+
+struct A;
+
+impl A {
+    #[debug_handler]
+    async fn handler() {}
+}
+
+fn main() {}

axum-debug/tests/pass/impl_future.rs

@@ -0,0 +1,9 @@
+use axum_debug::debug_handler;
+use std::future::Future;
+
+#[debug_handler]
+fn handler() -> impl Future<Output = ()> {
+    async {}
+}
+
+fn main() {}

axum-debug/tests/pass/impl_into_response.rs

@@ -0,0 +1,9 @@
+use axum_debug::debug_handler;
+use axum::response::IntoResponse;
+
+#[debug_handler]
+async fn handler() -> impl IntoResponse {
+    "hi!"
+}
+
+fn main() {}

axum-debug/tests/pass/mut_extractor.rs

@@ -0,0 +1,9 @@
+use axum_debug::debug_handler;
+
+#[debug_handler]
+async fn handler(mut foo: String) -> String {
+    foo += "bar";
+    foo
+}
+
+fn main() {}

axum-debug/tests/pass/ready.rs

@@ -0,0 +1,9 @@
+use axum_debug::debug_handler;
+use std::future::{Ready, ready};
+
+#[debug_handler]
+fn handler() -> Ready<()> {
+    ready(())
+}
+
+fn main() {}

axum-debug/tests/pass/returns_self.rs

@@ -0,0 +1,27 @@
+use axum::{
+    body::{Bytes, Full},
+    http::Response,
+    response::IntoResponse,
+};
+use axum_debug::debug_handler;
+use std::convert::Infallible;
+
+struct A;
+
+impl A {
+    #[debug_handler]
+    async fn handler() -> Self {
+        A
+    }
+}
+
+impl IntoResponse for A {
+    type Body = Full<Bytes>;
+    type BodyError = Infallible;
+
+    fn into_response(self) -> Response<Self::Body> {
+        todo!()
+    }
+}
+
+fn main() {}

axum-debug/tests/pass/self_receiver.rs

@@ -1,5 +1,8 @@
+use axum::{
+    async_trait,
+    extract::{FromRequest, RequestParts},
+};
 use axum_debug::debug_handler;
-use axum::{async_trait, extract::{FromRequest, RequestParts}};
 
 struct A;