Fix prost proto packages not sanitizing to valid module names (#2044)

* Fix prost proto packages not sanitizing to lowercase

* Add support for snake casing to match prost-build

proto/prost/private/3rdparty/BUILD.heck.bazel

@@ -0,0 +1,20 @@
+load("@rules_rust//rust:defs.bzl", "rust_library")
+
+package(default_visibility = ["//visibility:public"])
+
+rust_library(
+    name = "heck",
+    srcs = glob(["**/*.rs"]),
+    crate_features = [
+        "default",
+    ],
+    crate_root = "src/lib.rs",
+    edition = "2018",
+    rustc_flags = ["--cap-lints=allow"],
+    tags = [
+        "manual",
+        "noclippy",
+        "norustfmt",
+    ],
+    version = "0.4.1",
+)

proto/prost/private/BUILD.bazel

@@ -13,7 +13,10 @@ rust_binary(
     srcs = ["protoc_wrapper.rs"],
     edition = RUST_EDITION,
     visibility = ["//visibility:public"],
-    deps = [":current_prost_runtime"],
+    deps = [
+        ":current_prost_runtime",
+        "@rules_rust_prost__heck//:heck",
+    ],
 )
 
 rust_test(

proto/prost/private/protoc_wrapper.rs

@@ -9,6 +9,7 @@ use std::path::PathBuf;
 use std::process;
 use std::{env, fmt};
 
+use heck::ToSnakeCase;
 use prost::Message;
 use prost_types::{
     DescriptorProto, EnumDescriptorProto, FileDescriptorProto, FileDescriptorSet,
@@ -44,6 +45,18 @@ fn find_generated_rust_files(out_dir: &Path) -> BTreeSet<PathBuf> {
     all_rs_files
 }
 
+fn snake_cased_package_name(package: &str) -> String {
+    if package == "_" {
+        return package.to_owned();
+    }
+
+    package
+        .split('.')
+        .map(|s| s.to_snake_case())
+        .collect::<Vec<_>>()
+        .join(".")
+}
+
 /// Rust module definition.
 #[derive(Debug, Default)]
 struct Module {
@@ -121,20 +134,25 @@ fn generate_lib_rs(prost_outputs: &BTreeSet<PathBuf>, is_tonic: bool) -> String
                 .to_string()
         };
 
-        let module_name = package.to_lowercase().to_string();
-
-        if module_name.is_empty() {
+        if package.is_empty() {
             continue;
         }
 
-        let mut name = module_name.clone();
-        if module_name.contains('.') {
-            name = module_name
+        let name = if package == "_" {
+            package.clone()
+        } else if package.contains('.') {
+            package
                 .rsplit_once('.')
                 .expect("Failed to split on '.'")
                 .1
-                .to_string();
-        }
+                .to_snake_case()
+                .to_string()
+        } else {
+            package.to_snake_case()
+        };
+
+        // Avoid a stack overflow by skipping a known bad package name
+        let module_name = snake_cased_package_name(&package);
 
         module_info.insert(
             module_name.clone(),
@@ -145,7 +163,7 @@ fn generate_lib_rs(prost_outputs: &BTreeSet<PathBuf>, is_tonic: bool) -> String
             },
         );
 
-        let module_parts = module_name.split('.').collect::<Vec<&str>>();
+        let module_parts = module_name.split('.').collect::<Vec<_>>();
         for parent_module_index in 0..module_parts.len() {
             let child_module_index = parent_module_index + 1;
             if child_module_index >= module_parts.len() {
@@ -307,7 +325,7 @@ fn descriptor_set_file_to_extern_paths(
     file: &FileDescriptorProto,
 ) {
     let package = file.package.clone().unwrap_or_default();
-    let rust_path = rust_path.join(&package.replace('.', "::"));
+    let rust_path = rust_path.join(&snake_cased_package_name(&package).replace('.', "::"));
     let proto_path = ProtoPath(package);
 
     for message_type in file.message_type.iter() {
@@ -1043,6 +1061,11 @@ mod test {
             assert_eq!(proto_path.to_string(), "foo.bar");
             assert_eq!(proto_path.join("baz"), ProtoPath::from("foo.bar.baz"));
         }
+        {
+            let proto_path = ProtoPath::from("Foo.baR");
+            assert_eq!(proto_path.to_string(), "Foo.baR");
+            assert_eq!(proto_path.join("baz"), ProtoPath::from("Foo.baR.baz"));
+        }
     }
 
     #[test]

proto/prost/private/tests/sanitized_modules/BUILD.bazel

@@ -0,0 +1,33 @@
+load("@rules_proto//proto:defs.bzl", "proto_library")
+load("@rules_rust//rust:defs.bzl", "rust_test")
+load("//proto/prost:defs.bzl", "rust_prost_library")
+
+proto_library(
+    name = "foo_proto",
+    srcs = [
+        "foo.proto",
+    ],
+    strip_import_prefix = "/proto/prost/private/tests/sanitized_modules",
+)
+
+proto_library(
+    name = "bar_proto",
+    srcs = [
+        "bar.proto",
+    ],
+    deps = [
+        "foo_proto",
+    ],
+)
+
+rust_prost_library(
+    name = "bar_proto_rs",
+    proto = ":bar_proto",
+)
+
+rust_test(
+    name = "sanitized_modules_test",
+    srcs = ["sanitized_modules_test.rs"],
+    edition = "2021",
+    deps = [":bar_proto_rs"],
+)

proto/prost/private/tests/sanitized_modules/bar.proto

@@ -0,0 +1,17 @@
+syntax = "proto3";
+
+import "foo.proto";
+
+package bAR.bAz.QAZ.QuX;
+
+message Bar {
+  string name = 1;
+
+  Foo.QuuX.CoRgE.GRAULT.gaRply.Foo foo = 2;
+
+  Foo.QuuX.CoRgE.GRAULT.gaRply.Foo.NestedFoo nested_foo = 3;
+
+  message Baz {
+    string name = 4;
+  }
+}

proto/prost/private/tests/sanitized_modules/foo.proto

@@ -0,0 +1,11 @@
+syntax = "proto3";
+
+package Foo.QuuX.CoRgE.GRAULT.gaRply;
+
+message Foo {
+  string name = 1;
+
+  message NestedFoo {
+    string name = 2;
+  }
+}

proto/prost/private/tests/sanitized_modules/sanitized_modules_test.rs

@@ -0,0 +1,26 @@
+//! Tests protos with various capitalizations in their package names are
+//! consumable in an expected way.
+
+use bar_proto::b_ar::b_az::qaz::qu_x::bar::Baz as BazMessage;
+use bar_proto::b_ar::b_az::qaz::qu_x::Bar as BarMessage;
+use foo_proto::foo::quu_x::co_rg_e::grault::ga_rply::foo::NestedFoo as NestedFooMessage;
+use foo_proto::foo::quu_x::co_rg_e::grault::ga_rply::Foo as FooMessage;
+
+#[test]
+fn test_packages() {
+    let bar_message = BarMessage {
+        name: "bar".to_string(),
+        foo: Some(FooMessage {
+            name: "foo".to_string(),
+        }),
+        nested_foo: Some(NestedFooMessage {
+            name: "nested_foo".to_string(),
+        }),
+    };
+    let baz_message = BazMessage {
+        name: "baz".to_string(),
+    };
+
+    assert_eq!(bar_message.name, "bar");
+    assert_eq!(baz_message.name, "baz");
+}

proto/prost/repositories.bzl

@@ -22,3 +22,13 @@ def rust_prost_dependencies():
         strip_prefix = "protobuf-3.18.0",
         urls = ["https://github.com/protocolbuffers/protobuf/releases/download/v3.18.0/protobuf-all-3.18.0.tar.gz"],
     )
+
+    maybe(
+        http_archive,
+        name = "rules_rust_prost__heck",
+        sha256 = "95505c38b4572b2d910cecb0281560f54b440a19336cbbcb27bf6ce6adc6f5a8",
+        type = "tar.gz",
+        urls = ["https://crates.io/api/v1/crates/heck/0.4.1/download"],
+        strip_prefix = "heck-0.4.1",
+        build_file = Label("@rules_rust//proto/prost/private/3rdparty/crates:BUILD.heck-0.4.1.bazel"),
+    )