[2/n] handle unparseable local files (e.g., conflict markers)

.github/workflows/ci.yml

@@ -57,6 +57,9 @@ jobs:
         with:
           key: partition-${{ matrix.partition }}
       - uses: taiki-e/install-action@nextest
+      - uses: taiki-e/install-action@v2
+        with:
+          tool: jj-cli
       - name: Build
         run: cargo build
       - name: Run tests

crates/dropshot-api-manager/src/cmd/debug.rs

@@ -113,10 +113,14 @@ fn dump_structure<T: AsRawFiles>(
         for (version, files) in info.versions() {
             println!("        version {}:", version);
             for api_spec in files.as_raw_files() {
+                let version_str = api_spec
+                    .version()
+                    .map(|v| v.to_string())
+                    .unwrap_or_else(|| "unparseable".to_string());
                 println!(
                     "            file {} (v{})",
                     api_spec.spec_file_name().path(),
-                    api_spec.version()
+                    version_str
                 );
             }
         }

crates/dropshot-api-manager/src/git.rs

@@ -90,13 +90,23 @@ pub enum CommitHashParseError {
     InvalidHex(hex::FromHexError),
 }
 
-/// Given a revision, return its merge base with HEAD
+/// Given a revision, return its merge base with the current working state.
+///
+/// If we're in the middle of a merge (MERGE_HEAD exists), we use MERGE_HEAD
+/// instead of HEAD for the merge base calculation. This is important because
+/// during a merge conflict, HEAD points to our branch while MERGE_HEAD points
+/// to the branch being merged in. Using MERGE_HEAD ensures we see blessed
+/// documents from the incoming branch.
 pub fn git_merge_base_head(
     repo_root: &Utf8Path,
     revision: &GitRevision,
 ) -> anyhow::Result<GitRevision> {
+    // Check if we're in a merge state. If so, use MERGE_HEAD instead of HEAD.
+    let base_ref =
+        if git_merge_head_exists(repo_root) { "MERGE_HEAD" } else { "HEAD" };
+
     let mut cmd = git_start(repo_root);
-    cmd.arg("merge-base").arg("--all").arg("HEAD").arg(revision.as_str());
+    cmd.arg("merge-base").arg("--all").arg(base_ref).arg(revision.as_str());
     let label = cmd_label(&cmd);
     let stdout = do_run(&mut cmd)?;
     let stdout = stdout.trim();
@@ -110,6 +120,14 @@ pub fn git_merge_base_head(
     Ok(GitRevision::from(stdout.to_owned()))
 }
 
+/// Returns true if MERGE_HEAD exists, indicating we're in the middle of a
+/// merge.
+fn git_merge_head_exists(repo_root: &Utf8Path) -> bool {
+    let mut cmd = git_start(repo_root);
+    cmd.args(["rev-parse", "--verify", "--quiet", "MERGE_HEAD"]);
+    matches!(cmd.status(), Ok(status) if status.success())
+}
+
 /// List files recursively under some path `path` in Git revision `revision`.
 pub fn git_ls_tree(
     repo_root: &Utf8Path,