Enable diagnostic attributes for Rust 1.78+ (#2693)

axum-core/Cargo.toml

@@ -26,6 +26,7 @@ http-body = "1.0.0"
 http-body-util = "0.1.0"
 mime = "0.3.16"
 pin-project-lite = "0.2.7"
+rustversion = "1.0.9"
 sync_wrapper = "1.0.0"
 tower-layer = "0.3"
 tower-service = "0.3"
@@ -34,9 +35,6 @@ tower-service = "0.3"
 tower-http = { version = "0.5.0", optional = true, features = ["limit"] }
 tracing = { version = "0.1.37", default-features = false, optional = true }
 
-[build-dependencies]
-rustversion = "1.0.9"
-
 [dev-dependencies]
 axum = { path = "../axum", version = "0.7.2" }
 axum-extra = { path = "../axum-extra", features = ["typed-header"] }

axum-core/build.rs

@@ -1,7 +0,0 @@
-#[rustversion::nightly]
-fn main() {
-    println!("cargo:rustc-cfg=nightly_error_messages");
-}
-
-#[rustversion::not(nightly)]
-fn main() {}

axum-core/src/extract/mod.rs

@@ -43,8 +43,8 @@ mod private {
 ///
 /// [`axum::extract`]: https://docs.rs/axum/0.7/axum/extract/index.html
 #[async_trait]
-#[cfg_attr(
-    nightly_error_messages,
+#[rustversion::attr(
+    since(1.78),
     diagnostic::on_unimplemented(
         note = "Function argument is not a valid axum extractor. \nSee `https://docs.rs/axum/0.7/axum/extract/index.html` for details",
     )
@@ -70,8 +70,8 @@ pub trait FromRequestParts<S>: Sized {
 ///
 /// [`axum::extract`]: https://docs.rs/axum/0.7/axum/extract/index.html
 #[async_trait]
-#[cfg_attr(
-    nightly_error_messages,
+#[rustversion::attr(
+    since(1.78),
     diagnostic::on_unimplemented(
         note = "Function argument is not a valid axum extractor. \nSee `https://docs.rs/axum/0.7/axum/extract/index.html` for details",
     )