Update search path prefix when getting source db (#2380)

Summary:
Pull Request resolved: #2380

This should fix the sourcedb bug Jia mentioned last week, where sometimes search path prefix entries aren't used correctly. This happens when there's already a sourcedb entry loaded, so we skip appending the config root to the search path as expected.

Reviewed By: kinto0

Differential Revision: D92848242

fbshipit-source-id: 414a93c166c4c418edae7788b98749a391ac01b8

Author: connernilsen

crates/pyrefly_build/src/lib.rs

@@ -150,6 +150,11 @@ impl BuildSystem {
             Err(e) => return Some(Err(e)),
             Ok(path) => path,
         };
+
+        for path in &mut self.search_path_prefix {
+            *path = config_root.join(&path);
+        }
+
         let mut cache = BUILD_SYSTEM_CACHE.lock();
         let key = (repo_root.clone(), self.args.clone());
         if let Some(maybe_result) = cache.get(&key)
@@ -164,10 +169,6 @@ impl BuildSystem {
             &self.args
         );
 
-        for path in &mut self.search_path_prefix {
-            *path = config_root.join(&path);
-        }
-
         let querier: Arc<dyn SourceDbQuerier> = match &self.args {
             BuildSystemArgs::Buck(args) => Arc::new(BxlQuerier::new(args.clone())),
             BuildSystemArgs::Custom(args) => Arc::new(CustomQuerier::new(args.clone())),
@@ -179,3 +180,81 @@ impl BuildSystem {
         Some(Ok(source_db))
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use vec1::vec1;
+
+    use super::*;
+
+    #[test]
+    fn test_get_source_db_always_configures_paths() {
+        let mut bs = BuildSystem {
+            args: BuildSystemArgs::Custom(CustomQueryArgs {
+                command: vec1!["python3".to_owned()],
+                repo_root: None,
+            }),
+            ignore_if_build_system_missing: false,
+            search_path_prefix: vec![
+                PathBuf::from("path/to/project"),
+                PathBuf::from("/absolute/path/to/project"),
+            ],
+        };
+        let mut bs2 = bs.clone();
+
+        let root = Path::new("/root");
+
+        bs.get_source_db(root.to_path_buf()).unwrap().unwrap();
+        assert_eq!(
+            &bs.search_path_prefix,
+            &[
+                root.join("path/to/project"),
+                PathBuf::from("/absolute/path/to/project")
+            ]
+        );
+        bs2.get_source_db(root.to_path_buf()).unwrap().unwrap();
+        assert_eq!(
+            &bs2.search_path_prefix,
+            &[
+                root.join("path/to/project"),
+                PathBuf::from("/absolute/path/to/project")
+            ]
+        );
+
+        // double check that configuring twice doesn't corrupt path, even though it should
+        // never be called twice
+        bs2.get_source_db(root.to_path_buf()).unwrap().unwrap();
+        assert_eq!(
+            &bs2.search_path_prefix,
+            &[
+                root.join("path/to/project"),
+                PathBuf::from("/absolute/path/to/project")
+            ]
+        );
+    }
+
+    #[test]
+    fn test_build_system_not_exist() {
+        let mut bs = BuildSystem {
+            args: BuildSystemArgs::Custom(CustomQueryArgs {
+                command: vec1!["this_command_should_not_exist_?/".to_owned()],
+                repo_root: None,
+            }),
+            ignore_if_build_system_missing: false,
+            search_path_prefix: vec![],
+        };
+        let root = Path::new("/root");
+
+        bs.get_source_db(root.to_path_buf()).unwrap().unwrap_err();
+
+        let mut bs = BuildSystem {
+            args: BuildSystemArgs::Custom(CustomQueryArgs {
+                command: vec1!["this_command_should_not_exist_?/".to_owned()],
+                repo_root: None,
+            }),
+            ignore_if_build_system_missing: true,
+            search_path_prefix: vec![],
+        };
+        assert!(bs.get_source_db(root.to_path_buf()).is_none());
+    }
+}

crates/pyrefly_build/src/query/custom.rs

@@ -37,7 +37,7 @@ pub struct CustomQueryArgs {
 
     /// The root of the repository. Repo roots here will be shared between configs.
     #[serde(default)]
-    repo_root: Option<PathBuf>,
+    pub repo_root: Option<PathBuf>,
 }
 
 impl CustomQueryArgs {