fix: move proto code generation output to OUT_DIR, out of tree

bin/remote-prover/Cargo.toml

@@ -46,7 +46,15 @@ miden-testing   = { workspace = true }
 miden-tx        = { features = ["testing"], workspace = true }
 
 [build-dependencies]
+fs-err                             = { workspace = true }
 miden-node-proto-build             = { features = ["internal"], workspace = true }
 miden-node-rocksdb-cxx-linkage-fix = { workspace = true }
 miette                             = { features = ["fancy"], version = "7.5" }
 tonic-prost-build                  = { workspace = true }
+
+[package.metadata.cargo-machete]
+ignored = [
+  "http",
+  "prost",
+  "tonic-prost", # used in generated OUT_DIR code
+]

bin/remote-prover/build.rs

@@ -1,28 +1,28 @@
+use std::path::{Path, PathBuf};
+
+use fs_err as fs;
 use miden_node_proto_build::remote_prover_api_descriptor;
-use miette::IntoDiagnostic;
+use miette::{IntoDiagnostic, WrapErr};
 use tonic_prost_build::FileDescriptorSet;
 
-/// Defines whether the build script should generate files in `/src`.
-///
-/// The docs.rs build pipeline has a read-only filesystem, so we have to avoid writing to `src`,
-/// otherwise the docs will fail to build there. Note that writing to `OUT_DIR` is fine.
-const BUILD_GENERATED_FILES_IN_SRC: bool = option_env!("BUILD_PROTO").is_some();
-
-const GENERATED_OUT_DIR: &str = "src/generated";
-
 /// Generates Rust protobuf bindings.
 fn main() -> miette::Result<()> {
     miden_node_rocksdb_cxx_linkage_fix::configure();
-    println!("cargo:rerun-if-env-changed=BUILD_PROTO");
-    if !BUILD_GENERATED_FILES_IN_SRC {
-        return Ok(());
-    }
+
+    let dst_dir =
+        PathBuf::from(std::env::var("OUT_DIR").expect("OUT_DIR should be set")).join("generated");
+
+    // Remove all existing files.
+    let _ = fs::remove_dir_all(&dst_dir);
+    fs::create_dir(&dst_dir)
+        .into_diagnostic()
+        .wrap_err("creating destination folder")?;
 
     // Get the file descriptor set
     let remote_prover_descriptor = remote_prover_api_descriptor();
 
     // Build tonic code
-    build_tonic_from_descriptor(remote_prover_descriptor)?;
+    build_tonic_from_descriptor(remote_prover_descriptor, &dst_dir)?;
 
     Ok(())
 }
@@ -31,9 +31,12 @@ fn main() -> miette::Result<()> {
 // ================================================================================================
 
 /// Builds tonic code from a `FileDescriptorSet`
-fn build_tonic_from_descriptor(descriptor: FileDescriptorSet) -> miette::Result<()> {
+fn build_tonic_from_descriptor(
+    descriptor: FileDescriptorSet,
+    dst_dir: &Path,
+) -> miette::Result<()> {
     tonic_prost_build::configure()
-        .out_dir(GENERATED_OUT_DIR)
+        .out_dir(dst_dir)
         .build_server(true)
         .build_transport(true)
         .compile_fds_with_config(descriptor, tonic_prost_build::Config::new())

bin/remote-prover/src/generated/mod.rs

@@ -2,5 +2,7 @@
 #![allow(clippy::allow_attributes, reason = "generated by build.rs and tonic")]
 
 #[rustfmt::skip]
-mod remote_prover;
+pub mod remote_prover {
+    include!(concat!(env!("OUT_DIR"), "/generated/remote_prover.rs"));
+}
 pub use remote_prover::*;