change to git submodule init + warnings for submodule status

methods/build.rs

@@ -21,22 +21,9 @@ use risc0_build_ethereum::generate_solidity_files;
 const SOLIDITY_IMAGE_ID_PATH: &str = "../contracts/ImageID.sol";
 const SOLIDITY_ELF_PATH: &str = "../tests/Elf.sol";
 
-fn run_git_submodule_update() {
-    let output = Command::new("git")
-        .args(["submodule", "update", "--init"])
-        .output()
-        .expect("failed to run git submodule update in methods/build.rs");
-
-    if !output.status.success() {
-        panic!(
-            "git submodule update failed (methods/build.rs): {}",
-            String::from_utf8_lossy(&output.stderr)
-        );
-    }
-}
-
 fn main() {
-    run_git_submodule_update();
+    git_submodule_init();
+    check_submodule_state();
     println!("cargo:rerun-if-changed=.gitmodules");
 
     // Builds can be made deterministic, and thereby reproducible, by using Docker to build the
@@ -62,3 +49,85 @@ fn main() {
 
     generate_solidity_files(guests.as_slice(), &solidity_opts).unwrap();
 }
+
+/// Initializes git submodules by adding their configurations to .git/config.
+/// This is a one-time setup step that only needs to run on first clone of the repository.
+/// Does not fetch or update submodule contents.
+///
+/// # Warnings
+/// Prints a warning to stderr if the initialization fails, but does not interrupt the build process.
+fn git_submodule_init() {
+    let output = Command::new("git")
+        .args(["submodule", "init"])
+        .output()
+        .expect("failed to run git submodule init in methods/build.rs");
+
+    if !output.status.success() {
+        eprintln!(
+            "WARNING: git submodule init failed (methods/build.rs): {}",
+            String::from_utf8_lossy(&output.stderr)
+        );
+    }
+}
+
+/// Checks and reports the status of all git submodules in the project.
+/// Runs on every build to inform developers about the state of their submodules.
+///
+/// # Status Indicators
+/// - `-`: submodule is not initialized
+/// - `+`: submodule has local changes
+/// - ` `: submodule is clean (no warning displayed)
+///
+/// # Warnings
+/// Prints warnings for any non-clean states, but does not modify submodules
+/// or interrupt the build process.
+fn check_submodule_state() {
+    let status = Command::new("git")
+        .args(["submodule", "status"])
+        .output()
+        .expect("failed to run git submodule status");
+
+    if !status.status.success() {
+        println!(
+            "cargo:warning=failed to check git submodule status: {}",
+            String::from_utf8_lossy(&status.stderr)
+        );
+        return;
+    }
+
+    let output = String::from_utf8_lossy(&status.stdout);
+    let mut has_uninitialized = false;
+    let mut has_local_changes = false;
+
+    for line in output.lines() {
+        let path = line
+            .split_whitespace()
+            .nth(1)
+            .unwrap_or("unknown path")
+            .replace("../", "");
+
+        if let Some(first_char) = line.chars().next() {
+            match first_char {
+                '-' => {
+                    println!("cargo:warning=git submodule not initialized: {}", path);
+                    has_uninitialized = true;
+                }
+                '+' => {
+                    println!("cargo:warning=git submodule has local changes, this may cause unexpected behaviour: {}", path);
+                    has_local_changes = true;
+                }
+                _ => (),
+            }
+        }
+    }
+
+    if has_uninitialized {
+        println!(
+            "cargo:warning=to initialize missing submodules, run: git submodule update --init"
+        );
+    }
+
+    if has_local_changes {
+        println!("cargo:warning=to reset submodules to their expected versions, run: git submodule update --recursive");
+    }
+}