Add utoipa_axum bindings

This PR adds a new crate `utiopa-axum` which provides bindings between
`axum` and `utoipa`. It aims to blend as much as possible to the
existing philosophy of axum way of registering handlers.

This commit introduces new OpenApiRouter what wraps OpenApi and axum
Router which provides passthrough implementation for most of the axum
Router methods and collects and combines the OpenApi from registered
routes. Routes registred only via `routes!()` macro will get added to
the OpenApi.

Also this commit introduces `routes!()` macro which collects axum
handlers annotated with `#[utoipa::path()]` attribute macro to single
paths intance which is then provided to the OpenApiRouter.

Fixes #991

scripts/doc.sh

@@ -3,5 +3,5 @@
 # Generate utoipa workspace docs
 
 cargo +nightly doc -Z unstable-options --workspace --no-deps \
-    --features actix_extras,openapi_extensions,yaml,uuid,ulid,url,non_strict_integers,actix-web,axum,rocket,axum_handler \
+    --features actix_extras,openapi_extensions,yaml,uuid,ulid,url,non_strict_integers,actix-web,axum,rocket \
     --config 'build.rustdocflags = ["--cfg", "doc_cfg"]'

scripts/test.sh

@@ -22,7 +22,6 @@ for crate in $crates; do
         $CARGO test -p utoipa-gen --test path_derive_rocket --features rocket_extras
 
         $CARGO test -p utoipa-gen --test path_derive_axum_test --features axum_extras
-        $CARGO test -p utoipa-gen --test path_derive_axum_test --features axum_extras,axum_handler
         $CARGO test -p utoipa-gen --test path_derive_auto_into_responses_axum --features axum_extras,utoipa/auto_into_responses
     elif [[ "$crate" == "utoipa-swagger-ui" ]]; then
         $CARGO test -p utoipa-swagger-ui --features actix-web,rocket,axum
@@ -33,6 +32,6 @@ for crate in $crates; do
     elif [[ "$crate" == "utoipa-scalar" ]]; then
         $CARGO test -p utoipa-scalar --features actix-web,rocket,axum
     elif [[ "$crate" == "utoipa-axum" ]]; then
-        $CARGO test -p utoipa-axum 
+        $CARGO test -p utoipa-axum --features debug,utoipa/debug
     fi
 done

utoipa-axum/Cargo.toml

@@ -11,14 +11,20 @@ categories = ["web-programming"]
 authors = ["Juha Kukkonen <juha7kukkonen@gmail.com>"]
 rust-version.workspace = true
 
+[features]
+debug = []
+
 [dependencies]
 axum = { version = "0.7", default-features = false }
-once_cell = "1"
-utoipa = { version = "5.0.0-alpha.1", path = "../utoipa", default-features = false }
+utoipa = { version = "5.0.0-alpha", path = "../utoipa", default-features = false }
 async-trait = "0.1"
 tower-service = "0.3"
 tower-layer = "0.3.2"
+paste = "1.0"
 
 [package.metadata.docs.rs]
 features = []
 rustdoc-args = ["--cfg", "doc_cfg"]
+
+[lints.rust]
+unexpected_cfgs = { level = "warn", check-cfg = ['cfg(doc_cfg)'] }