feat: forwards-compatibility for handler visibility inheritance fix

relates to #2714

Author: robjtede

actix-web-codegen/Cargo.toml

@@ -15,6 +15,10 @@ rust-version.workspace = true
 [lib]
 proc-macro = true
 
+[features]
+default = ["force-pub"]
+force-pub = []
+
 [dependencies]
 actix-router = { version = "0.5", default-features = false }
 proc-macro2 = "1"

actix-web-codegen/src/route.rs

@@ -413,6 +413,13 @@ impl ToTokens for Route {
             doc_attributes,
         } = self;
 
+        #[allow(unused_variables)] // used when force-pub feature is disabled
+        let vis = &ast.vis;
+
+        // TODO(v5.0): remove the force-pub backwards-compatibility feature
+        #[cfg(feature = "force-pub")]
+        let vis = syn::Visibility::Public(<Token![pub]>::default());
+
         let registrations: TokenStream2 = args
             .iter()
             .map(|args| {
@@ -460,7 +467,7 @@ impl ToTokens for Route {
         let stream = quote! {
             #(#doc_attributes)*
             #[allow(non_camel_case_types, missing_docs)]
-            pub struct #name;
+            #vis struct #name;
 
             impl ::actix_web::dev::HttpServiceFactory for #name {
                 fn register(self, __config: &mut actix_web::dev::AppService) {

actix-web-codegen/tests/scopes.rs

@@ -49,7 +49,7 @@ mod scope_module {
     #[connect("/test2")]
     #[options("/test3")]
     #[trace("/test4")]
-    async fn multiple_separate_paths() -> impl Responder {
+    pub async fn multiple_separate_paths() -> impl Responder {
         HttpResponse::Ok().finish()
     }
 

actix-web/Cargo.toml

@@ -40,7 +40,16 @@ name = "actix_web"
 path = "src/lib.rs"
 
 [features]
-default = ["macros", "compress-brotli", "compress-gzip", "compress-zstd", "cookies", "http2", "unicode"]
+default = [
+    "macros",
+    "compress-brotli",
+    "compress-gzip",
+    "compress-zstd",
+    "cookies",
+    "http2",
+    "unicode",
+    "compat-routing-macros-force-pub",
+]
 
 # Brotli algorithm content-encoding support
 compress-brotli = ["actix-http/compress-brotli", "__compress"]
@@ -50,14 +59,15 @@ compress-gzip = ["actix-http/compress-gzip", "__compress"]
 compress-zstd = ["actix-http/compress-zstd", "__compress"]
 
 # Routing and runtime proc macros
-macros = ["actix-macros", "actix-web-codegen"]
+macros = ["dep:actix-macros", "dep:actix-web-codegen"]
 
 # Cookies support
-cookies = ["cookie"]
+cookies = ["dep:cookie"]
 
 # Secure & signed cookies
 secure-cookies = ["cookies", "cookie/secure"]
 
+# HTTP/2 support (including h2c).
 http2 = ["actix-http/http2"]
 
 # TLS via OpenSSL
@@ -84,6 +94,9 @@ __compress = []
 # io-uring feature only available for Linux OSes.
 experimental-io-uring = ["actix-server/io-uring"]
 
+# Opt-out forwards-compatibility for handler visibility inheritance fix.
+compat-routing-macros-force-pub = ["actix-web-codegen?/force-pub"]
+
 [dependencies]
 actix-codec = "0.5"
 actix-macros = { version = "0.2.3", optional = true }
@@ -95,7 +108,7 @@ actix-tls = { version = "3.4", default-features = false, optional = true }
 
 actix-http = { version = "3.7", features = ["ws"] }
 actix-router = { version = "0.5.3", default-features = false, features = ["http"] }
-actix-web-codegen = { version = "4.2", optional = true }
+actix-web-codegen = { version = "4.2", optional = true, default-features = false }
 
 ahash = "0.8"
 bytes = "1"