fix: implement cfg-aliases manually and remove build dep

Author: joshka

Cargo.toml

@@ -240,6 +240,3 @@ required-features = ["full"]
 name = "server"
 path = "tests/server.rs"
 required-features = ["full"]
-
-[build-dependencies]
-cfg_aliases = "0.2.1"

build.rs

@@ -1,25 +1,77 @@
-use cfg_aliases::cfg_aliases;
-
 fn main() {
-    cfg_aliases! {
-        http1: { feature = "http1" },
-        http2: { feature = "http2" },
-
-        client : { feature = "client" },
-        server : { feature = "server" },
-
-        ffi: { feature = "ffi" },
-        full: { feature = "full" },
-        nightly: { feature = "nightly" },
-        runtime: { feature = "runtime" },
-        tracing: { feature = "tracing" },
-
-        http_client: { all(any(http1, http2), client) },
-        http1_client: { all(http1, client) },
-        http2_client: { all(http2, client) },
-
-        http_server: { all(any(http1, http2), server) },
-        http1_server: { all(http1, server) },
-        http2_server: { all(http2, server) },
-    }
+    // Add to the list of expected config names and values that is used when checking the reachable
+    // cfg expressions with the unexpected_cfgs lint.
+    //
+    // See https://doc.rust-lang.org/cargo/reference/build-scripts.html#rustc-check-cfg
+    println!("cargo:rustc-check-cfg=cfg(http1)");
+    println!("cargo:rustc-check-cfg=cfg(http2)");
+    println!("cargo:rustc-check-cfg=cfg(client)");
+    println!("cargo:rustc-check-cfg=cfg(server)");
+    println!("cargo:rustc-check-cfg=cfg(ffi)");
+    println!("cargo:rustc-check-cfg=cfg(full)");
+    println!("cargo:rustc-check-cfg=cfg(nightly)");
+    println!("cargo:rustc-check-cfg=cfg(runtime)"); // TODO evaluate if this is needed (see below)
+    println!("cargo:rustc-check-cfg=cfg(tracing)");
+    println!("cargo:rustc-check-cfg=cfg(http_client)");
+    println!("cargo:rustc-check-cfg=cfg(http1_client)");
+    println!("cargo:rustc-check-cfg=cfg(http2_client)");
+    println!("cargo:rustc-check-cfg=cfg(http_server)");
+    println!("cargo:rustc-check-cfg=cfg(http1_server)");
+    println!("cargo:rustc-check-cfg=cfg(http2_server)");
+
+    // Add cfg flags that simplify using cfg expressions in the code. e.g. instead of
+    // `#[cfg(all(any(feature = "http1", feature = "http2"), feature = "server")]` you can use
+    // `#[cfg(http_server)]`
+    //
+    // See https://doc.rust-lang.org/cargo/reference/build-scripts.html#rustc-cfg
+    #[cfg(feature = "http1")]
+    println!("cargo:rustc-cfg=http1");
+
+    #[cfg(feature = "http2")]
+    println!("cargo:rustc-cfg=http2");
+
+    #[cfg(any(feature = "http1", feature = "http2"))]
+    println!("cargo:rustc-cfg=http");
+
+    #[cfg(feature = "client")]
+    println!("cargo:rustc-cfg=client");
+
+    #[cfg(feature = "server")]
+    println!("cargo:rustc-cfg=server");
+
+    #[cfg(feature = "ffi")]
+    println!("cargo:rustc-cfg=ffi");
+
+    #[cfg(feature = "full")]
+    println!("cargo:rustc-cfg=full");
+
+    #[cfg(feature = "nightly")]
+    println!("cargo:rustc-cfg=nightly");
+
+    // TODO: this feature doesn't actually exist in the cargo.toml
+    // this condition was added to simplify the conditions in src/mock.rs, but I'm not sure if those
+    // conditions were actually working as intended
+    // #[cfg(feature = "runtime")]
+    // println!("cargo:rustc-cfg=runtime");
+
+    #[cfg(feature = "tracing")]
+    println!("cargo:rustc-cfg=tracing");
+
+    #[cfg(all(any(feature = "http1", feature = "http2"), feature = "client"))]
+    println!("cargo:rustc-cfg=http_client");
+
+    #[cfg(all(feature = "http1", feature = "client"))]
+    println!("cargo:rustc-cfg=http1_client");
+
+    #[cfg(all(feature = "http2", feature = "client"))]
+    println!("cargo:rustc-cfg=http2_client");
+
+    #[cfg(all(any(feature = "http1", feature = "http2"), feature = "server"))]
+    println!("cargo:rustc-cfg=http_server");
+
+    #[cfg(all(feature = "http1", feature = "server"))]
+    println!("cargo:rustc-cfg=http1_server");
+
+    #[cfg(all(feature = "http2", feature = "server"))]
+    println!("cargo:rustc-cfg=http2_server");
 }