codegen: skip rustfmt for generated mod.rs

.gitignore

@@ -6,7 +6,7 @@ Cargo.lock
 .idea
 *.o
 example/protocols/**/*.rs
-!example/protocols/**/mod.rs
+!example/protocols/mod.rs
 example-prost/protocols/**/*.rs
 !example-prost/protocols/**/mod.rs
 src/ttrpc.rs

compiler/src/codegen.rs

@@ -743,7 +743,8 @@ pub fn gen(
 /// Generates ttrpc service files and writes them to `out_dir`.
 ///
 /// When [`Customize::gen_mod`](crate::Customize::gen_mod) is enabled, this function also creates
-/// or updates `mod.rs` without discarding existing module declarations.
+/// or updates `mod.rs` without discarding existing module declarations. Generated indexes opt out
+/// of rustfmt, and existing comments and attributes retain their order.
 ///
 /// # Errors
 ///
@@ -762,13 +763,18 @@ pub fn gen_and_write(
 
     if customize.gen_mod {
         let file_path = out_dir.join("mod.rs");
-        let mut set = HashSet::new();
-        let mut lines = Vec::new();
+        let generated = "// @generated";
+        let rustfmt_skip = "#![cfg_attr(rustfmt, rustfmt::skip)]";
+        let mut lines = vec![generated.to_owned(), rustfmt_skip.to_owned()];
+        let mut set: HashSet<_> = lines.iter().cloned().collect();
         // Preserve existing order so comments and attributes stay with their modules.
         if let Ok(file) = File::open(&file_path) {
             let reader = io::BufReader::new(file);
             for line in reader.lines() {
                 let line = line?;
+                if line == generated || line == rustfmt_skip {
+                    continue;
+                }
                 set.insert(line.clone());
                 lines.push(line);
             }
@@ -842,7 +848,7 @@ mod tests {
     use super::*;
 
     #[test]
-    fn generated_mod_rs_is_stable_and_preserves_existing_lines() {
+    fn generated_mod_rs_skips_rustfmt_and_preserves_existing_lines() {
         let descriptors: Vec<_> = ["zeta.proto", "alpha.proto"]
             .iter()
             .map(|&name| FileDescriptorProto {
@@ -858,9 +864,26 @@ mod tests {
             gen_mod: true,
             ..Default::default()
         };
-        let existing = "// @generated\n\n// Keep this module gated.\n#[cfg(unix)]\npub mod custom;\n\n#[cfg(unix)]\npub mod another;\npub mod alpha_ttrpc;\n";
-
-        for initial in [None, Some(existing)] {
+        let existing = "\n// Keep this module gated.\n#[cfg(unix)]\npub mod custom;\n\n#[cfg(unix)]\npub mod another;\npub mod alpha_ttrpc;\n";
+        let protobuf_modules = "\npub mod alpha;\npub mod zeta;\n";
+        let header = "// @generated\n#![cfg_attr(rustfmt, rustfmt::skip)]\n";
+        let existing_index = format!("// @generated\n{existing}");
+        let protobuf_index = format!("// @generated\n{protobuf_modules}");
+
+        for (initial, expected) in [
+            (
+                None,
+                format!("{header}pub mod alpha_ttrpc;\npub mod zeta_ttrpc;\n"),
+            ),
+            (
+                Some(existing_index.as_str()),
+                format!("{header}{existing}pub mod zeta_ttrpc;\n"),
+            ),
+            (
+                Some(protobuf_index.as_str()),
+                format!("{header}{protobuf_modules}pub mod alpha_ttrpc;\npub mod zeta_ttrpc;\n"),
+            ),
+        ] {
             let dir = tempfile::tempdir().unwrap();
             let path = dir.path().join("mod.rs");
             if let Some(contents) = initial {
@@ -872,10 +895,6 @@ mod tests {
                 "alpha.proto".to_owned(),
             ];
             gen_and_write(&descriptors, &inputs, dir.path(), &customize).unwrap();
-            let expected = match initial {
-                Some(contents) => format!("{contents}pub mod zeta_ttrpc;\n"),
-                None => "pub mod alpha_ttrpc;\npub mod zeta_ttrpc;\n".to_owned(),
-            };
             assert_eq!(fs::read_to_string(&path).unwrap(), expected);
 
             inputs.reverse();

ttrpc-codegen/tests/well_known.rs

@@ -3,7 +3,7 @@ use std::fs;
 use std::path::{Path, PathBuf};
 
 use tempfile::TempDir;
-use ttrpc_codegen::{parse_and_typecheck, Codegen, Customize};
+use ttrpc_codegen::{parse_and_typecheck, Codegen, Customize, ProtobufCustomize};
 
 fn proto_dir() -> PathBuf {
     Path::new(env!("CARGO_MANIFEST_DIR")).join("tests/protos")
@@ -46,11 +46,15 @@ fn generates_runtime_paths_for_embedded_types() {
             .rust_protobuf()
             .customize(Customize {
                 async_all,
+                gen_mod: true,
                 ..Default::default()
             })
+            .rust_protobuf_customize(ProtobufCustomize::default().gen_mod_rs(true))
             .run()
             .unwrap();
 
+        let modules = fs::read_to_string(output.path().join("mod.rs")).unwrap();
+        assert!(modules.starts_with("// @generated\n#![cfg_attr(rustfmt, rustfmt::skip)]\n"));
         let messages = fs::read_to_string(output.path().join("well_known.rs")).unwrap();
         let services = fs::read_to_string(output.path().join("well_known_ttrpc.rs")).unwrap();
         let timestamp = "::protobuf::well_known_types::timestamp::Timestamp";