From e43b1c7f3ea011ee48ccfaff30820f36937c4ab4 Mon Sep 17 00:00:00 2001
From: Tiziano Santoro <tzn@google.com>
Date: Tue, 2 Jan 2024 19:52:14 +0000
Subject: [PATCH] Fix micro_rpc cross workspace dependency

Add a manual test to check regressions in the future.

Ref #4573
---
 Cargo.lock                                  |  7 +++++++
 Cargo.toml                                  |  2 +-
 micro_rpc/build.rs                          |  7 ++-----
 micro_rpc_workspace_test/.cargo/config.toml |  2 ++
 micro_rpc_workspace_test/Cargo.toml         |  7 +++++++
 micro_rpc_workspace_test/README.md          | 15 +++++++++++++++
 micro_rpc_workspace_test/src/main.rs        |  3 +++
 7 files changed, 37 insertions(+), 6 deletions(-)
 create mode 100644 micro_rpc_workspace_test/.cargo/config.toml
 create mode 100644 micro_rpc_workspace_test/Cargo.toml
 create mode 100644 micro_rpc_workspace_test/README.md
 create mode 100644 micro_rpc_workspace_test/src/main.rs

diff --git a/Cargo.lock b/Cargo.lock
index ca3f0bd1f48..0545f24eb1b 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1668,6 +1668,13 @@ dependencies = [
  "tokio",
 ]
 
+[[package]]
+name = "micro_rpc_workspace_test"
+version = "0.1.0"
+dependencies = [
+ "micro_rpc",
+]
+
 [[package]]
 name = "mime"
 version = "0.3.16"
diff --git a/Cargo.toml b/Cargo.toml
index 4a244ba78ae..2b91f3f31ac 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -4,7 +4,7 @@ members = [
   "linux_boot_params",
   "micro_rpc",
   "micro_rpc_build",
-  "micro_rpc_tests",
+  "micro_rpc_tests", "micro_rpc_workspace_test",
   "oak_attestation_verification",
   "oak_channel",
   "oak_client",
diff --git a/micro_rpc/build.rs b/micro_rpc/build.rs
index 794274b955d..5bbd3e02adc 100644
--- a/micro_rpc/build.rs
+++ b/micro_rpc/build.rs
@@ -16,11 +16,8 @@
 
 fn main() {
     micro_rpc_build::compile(
-        &[format!(
-            "{}proto/micro_rpc/messages.proto",
-            env!("WORKSPACE_ROOT")
-        )],
-        &[env!("WORKSPACE_ROOT")],
+        &["../proto/micro_rpc/messages.proto"],
+        &["../proto"],
         Default::default(),
     );
 }
diff --git a/micro_rpc_workspace_test/.cargo/config.toml b/micro_rpc_workspace_test/.cargo/config.toml
new file mode 100644
index 00000000000..1fbc5068780
--- /dev/null
+++ b/micro_rpc_workspace_test/.cargo/config.toml
@@ -0,0 +1,2 @@
+[env]
+WORKSPACE_ROOT = { value = "_invalid_workspace_root_" }
diff --git a/micro_rpc_workspace_test/Cargo.toml b/micro_rpc_workspace_test/Cargo.toml
new file mode 100644
index 00000000000..fa3a003e6ce
--- /dev/null
+++ b/micro_rpc_workspace_test/Cargo.toml
@@ -0,0 +1,7 @@
+[package]
+name = "micro_rpc_workspace_test"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+micro_rpc = { path = "../micro_rpc" }
diff --git a/micro_rpc_workspace_test/README.md b/micro_rpc_workspace_test/README.md
new file mode 100644
index 00000000000..9e375fd2572
--- /dev/null
+++ b/micro_rpc_workspace_test/README.md
@@ -0,0 +1,15 @@
+This directory contains a manual test to check whether the `micro_rpc` crate can
+be depended on from a crate in another workspace.
+
+See https://github.com/project-oak/oak/issues/4573 for context.
+
+This crate overwrites the `WORKSPACE_ROOT` env variable with an invalid value in
+the `.cargo/config.toml` file, which is necessary to shadow the corresponding
+one in the root of this repository, to simulate an external workspace that would
+not have that env variable set.
+
+To reproduce the issue, run the following command from the repository root:
+
+```bash
+env --chdir=./micro_rpc_workspace_test bash -c 'cargo clean && cargo build'
+```
diff --git a/micro_rpc_workspace_test/src/main.rs b/micro_rpc_workspace_test/src/main.rs
new file mode 100644
index 00000000000..e7a11a969c0
--- /dev/null
+++ b/micro_rpc_workspace_test/src/main.rs
@@ -0,0 +1,3 @@
+fn main() {
+    println!("Hello, world!");
+}