Generate correct bound for non-last extractor in #[debug_handler] (#1299)

* Support running a single UI test

* Generate correct `FromRequestParts` bound

* don't depend on itertools

axum-macros/src/debug_handler.rs

@@ -1,3 +1,4 @@
+use crate::with_position::{Position, WithPosition};
 use proc_macro2::TokenStream;
 use quote::{format_ident, quote, quote_spanned};
 use std::collections::HashSet;
@@ -173,12 +174,16 @@ fn check_inputs_impls_from_request(
         FnArg::Typed(typed) => is_self_pat_type(typed),
     });
 
-    item_fn
+    WithPosition::new(item_fn.sig.inputs.iter())
-        .sig
-        .inputs
-        .iter()
         .enumerate()
         .map(|(idx, arg)| {
+            let must_impl_from_request_parts = match &arg {
+                Position::First(_) | Position::Middle(_) => true,
+                Position::Last(_) | Position::Only(_) => false,
+            };
+
+            let arg = arg.into_inner();
+
             let (span, ty) = match arg {
                 FnArg::Receiver(receiver) => {
                     if receiver.reference.is_some() {
@@ -228,11 +233,27 @@ fn check_inputs_impls_from_request(
                 }
             };
 
+            let check_fn_generics = if must_impl_from_request_parts {
+                quote! {}
+            } else {
+                quote! { <M> }
+            };
+
+            let from_request_bound = if must_impl_from_request_parts {
+                quote! {
+                    #ty: ::axum::extract::FromRequestParts<#state_ty> + Send
+                }
+            } else {
+                quote! {
+                    #ty: ::axum::extract::FromRequest<#state_ty, #body_ty, M> + Send
+                }
+            };
+
             quote_spanned! {span=>
                 #[allow(warnings)]
-                fn #check_fn<M>()
+                fn #check_fn #check_fn_generics()
                 where
-                    #ty: ::axum::extract::FromRequest<#state_ty, #body_ty, M> + Send,
+                    #from_request_bound,
                 {}
 
                 // we have to call the function to actually trigger a compile error
@@ -472,15 +493,5 @@ fn state_type_from_args(item_fn: &ItemFn) -> Option<Type> {
 
 #[test]
 fn ui() {
-    #[rustversion::stable]
+    crate::run_ui_tests("debug_handler");
-    fn go() {
-        let t = trybuild::TestCases::new();
-        t.compile_fail("tests/debug_handler/fail/*.rs");
-        t.pass("tests/debug_handler/pass/*.rs");
-    }
-
-    #[rustversion::not(stable)]
-    fn go() {}
-
-    go();
 }

axum-macros/src/from_request.rs

@@ -564,17 +564,7 @@ fn impl_enum_by_extracting_all_at_once(
 
 #[test]
 fn ui() {
-    #[rustversion::stable]
+    crate::run_ui_tests("from_request");
-    fn go() {
-        let t = trybuild::TestCases::new();
-        t.compile_fail("tests/from_request/fail/*.rs");
-        t.pass("tests/from_request/pass/*.rs");
-    }
-
-    #[rustversion::not(stable)]
-    fn go() {}
-
-    go();
 }
 
 /// For some reason the compiler error for this is different locally and on CI. No idea why... So

axum-macros/src/lib.rs

@@ -50,6 +50,7 @@ use syn::parse::Parse;
 mod debug_handler;
 mod from_request;
 mod typed_path;
+mod with_position;
 
 /// Derive an implementation of [`FromRequest`].
 ///
@@ -561,3 +562,37 @@ where
         Err(err) => err.into_compile_error().into(),
     }
 }
+
+#[cfg(test)]
+fn run_ui_tests(directory: &str) {
+    #[rustversion::stable]
+    fn go(directory: &str) {
+        let t = trybuild::TestCases::new();
+
+        if let Ok(mut path) = std::env::var("AXUM_TEST_ONLY") {
+            if let Some(path_without_prefix) = path.strip_prefix("axum-macros/") {
+                path = path_without_prefix.to_owned();
+            }
+
+            if !path.contains(&format!("/{}/", directory)) {
+                return;
+            }
+
+            if path.contains("/fail/") {
+                t.compile_fail(path);
+            } else if path.contains("/pass/") {
+                t.pass(path);
+            } else {
+                panic!()
+            }
+        } else {
+            t.compile_fail(format!("tests/{}/fail/*.rs", directory));
+            t.pass(format!("tests/{}/pass/*.rs", directory));
+        }
+    }
+
+    #[rustversion::not(stable)]
+    fn go(directory: &str) {}
+
+    go(directory);
+}

axum-macros/src/typed_path.rs

@@ -423,15 +423,5 @@ fn map_err_rejection(rejection: &Option<syn::Path>) -> TokenStream {
 
 #[test]
 fn ui() {
-    #[rustversion::stable]
+    crate::run_ui_tests("typed_path");
-    fn go() {
-        let t = trybuild::TestCases::new();
-        t.compile_fail("tests/typed_path/fail/*.rs");
-        t.pass("tests/typed_path/pass/*.rs");
-    }
-
-    #[rustversion::not(stable)]
-    fn go() {}
-
-    go();
 }

axum-macros/src/with_position.rs

@@ -0,0 +1,116 @@
+// this is copied from itertools under the following license
+//
+// Copyright (c) 2015
+//
+// Permission is hereby granted, free of charge, to any
+// person obtaining a copy of this software and associated
+// documentation files (the "Software"), to deal in the
+// Software without restriction, including without
+// limitation the rights to use, copy, modify, merge,
+// publish, distribute, sublicense, and/or sell copies of
+// the Software, and to permit persons to whom the Software
+// is furnished to do so, subject to the following
+// conditions:
+//
+// The above copyright notice and this permission notice
+// shall be included in all copies or substantial portions
+// of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF
+// ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
+// TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
+// PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT
+// SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+// CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR
+// IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+// DEALINGS IN THE SOFTWARE.
+
+use std::iter::{Fuse, FusedIterator, Peekable};
+
+pub(crate) struct WithPosition<I>
+where
+    I: Iterator,
+{
+    handled_first: bool,
+    peekable: Peekable<Fuse<I>>,
+}
+
+impl<I> WithPosition<I>
+where
+    I: Iterator,
+{
+    pub(crate) fn new(iter: I) -> WithPosition<I> {
+        WithPosition {
+            handled_first: false,
+            peekable: iter.fuse().peekable(),
+        }
+    }
+}
+
+impl<I> Clone for WithPosition<I>
+where
+    I: Clone + Iterator,
+    I::Item: Clone,
+{
+    fn clone(&self) -> Self {
+        Self {
+            handled_first: self.handled_first,
+            peekable: self.peekable.clone(),
+        }
+    }
+}
+
+#[derive(Copy, Clone, Debug, PartialEq)]
+pub(crate) enum Position<T> {
+    First(T),
+    Middle(T),
+    Last(T),
+    Only(T),
+}
+
+impl<T> Position<T> {
+    pub(crate) fn into_inner(self) -> T {
+        match self {
+            Position::First(x) | Position::Middle(x) | Position::Last(x) | Position::Only(x) => x,
+        }
+    }
+}
+
+impl<I: Iterator> Iterator for WithPosition<I> {
+    type Item = Position<I::Item>;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        match self.peekable.next() {
+            Some(item) => {
+                if !self.handled_first {
+                    // Haven't seen the first item yet, and there is one to give.
+                    self.handled_first = true;
+                    // Peek to see if this is also the last item,
+                    // in which case tag it as `Only`.
+                    match self.peekable.peek() {
+                        Some(_) => Some(Position::First(item)),
+                        None => Some(Position::Only(item)),
+                    }
+                } else {
+                    // Have seen the first item, and there's something left.
+                    // Peek to see if this is the last item.
+                    match self.peekable.peek() {
+                        Some(_) => Some(Position::Middle(item)),
+                        None => Some(Position::Last(item)),
+                    }
+                }
+            }
+            // Iterator is finished.
+            None => None,
+        }
+    }
+
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        self.peekable.size_hint()
+    }
+}
+
+impl<I> ExactSizeIterator for WithPosition<I> where I: ExactSizeIterator {}
+
+impl<I: Iterator> FusedIterator for WithPosition<I> {}

axum-macros/tests/debug_handler/fail/argument_not_extractor.stderr

@@ -16,7 +16,10 @@ error[E0277]: the trait bound `bool: FromRequestParts<()>` is not satisfied
           and 26 others
   = note: required because of the requirements on the impl of `FromRequest<(), Body, axum_core::extract::private::ViaParts>` for `bool`
 note: required by a bound in `__axum_macros_check_handler_0_from_request_check`
- --> tests/debug_handler/fail/argument_not_extractor.rs:4:23
+ --> tests/debug_handler/fail/argument_not_extractor.rs:3:1
   |
+3 | #[debug_handler]
+  | ^^^^^^^^^^^^^^^^ required by this bound in `__axum_macros_check_handler_0_from_request_check`
 4 | async fn handler(foo: bool) {}
-  |                       ^^^^ required by this bound in `__axum_macros_check_handler_0_from_request_check`
+  |                       ---- required by a bound in this
+  = note: this error originates in the attribute macro `debug_handler` (in Nightly builds, run with -Z macro-backtrace for more info)

axum-macros/tests/debug_handler/fail/doesnt_implement_from_request_parts.rs

@@ -0,0 +1,7 @@
+use axum_macros::debug_handler;
+use axum::http::Method;
+
+#[debug_handler]
+async fn handler(_: String, _: Method) {}
+
+fn main() {}

axum-macros/tests/debug_handler/fail/doesnt_implement_from_request_parts.stderr

@@ -0,0 +1,18 @@
+error[E0277]: the trait bound `String: FromRequestParts<()>` is not satisfied
+ --> tests/debug_handler/fail/doesnt_implement_from_request_parts.rs:4:1
+  |
+4 | #[debug_handler]
+  | ^^^^^^^^^^^^^^^^ the trait `FromRequestParts<()>` is not implemented for `String`
+  |
+  = help: the following other types implement trait `FromRequestParts<S>`:
+            <() as FromRequestParts<S>>
+            <(T1, T2) as FromRequestParts<S>>
+            <(T1, T2, T3) as FromRequestParts<S>>
+            <(T1, T2, T3, T4) as FromRequestParts<S>>
+            <(T1, T2, T3, T4, T5) as FromRequestParts<S>>
+            <(T1, T2, T3, T4, T5, T6) as FromRequestParts<S>>
+            <(T1, T2, T3, T4, T5, T6, T7) as FromRequestParts<S>>
+            <(T1, T2, T3, T4, T5, T6, T7, T8) as FromRequestParts<S>>
+          and 26 others
+  = help: see issue #48214
+  = note: this error originates in the attribute macro `debug_handler` (in Nightly builds, run with -Z macro-backtrace for more info)

axum-macros/tests/debug_handler/pass/result_impl_into_response.rs

@@ -1,4 +1,4 @@
-use axum::{async_trait, extract::FromRequest, http::Request, response::IntoResponse};
+use axum::{async_trait, extract::FromRequestParts, http::request::Parts, response::IntoResponse};
 use axum_macros::debug_handler;
 
 fn main() {}
@@ -116,14 +116,13 @@ impl A {
 }
 
 #[async_trait]
-impl<S, B> FromRequest<S, B> for A
+impl<S> FromRequestParts<S> for A
 where
-    B: Send + 'static,
     S: Send + Sync,
 {
     type Rejection = ();
 
-    async fn from_request(_req: Request<B>, _state: &S) -> Result<Self, Self::Rejection> {
+    async fn from_request_parts(_parts: &mut Parts, _state: &S) -> Result<Self, Self::Rejection> {
         unimplemented!()
     }
 }