move root setting into config

Summary:
The config path and root of the config are tightly coupled. This change makes it
so that the config has an optional `root` field to set the root of the compiler.

By default, the directory of the config is the root, otherwise the relative path
to the root is used.

Reviewed By: josephsavona

Differential Revision: D22498223

fbshipit-source-id: b857dfa77c9f815802a4b96dc07a4111af717aff

compiler/crates/relay-compiler/src/config.rs

@@ -54,33 +54,27 @@ impl Config {
             .filter(|project_config| project_config.enabled)
     }
 
-    pub fn load(root_dir: PathBuf, config_path: PathBuf) -> Result<Self> {
+    pub fn load(config_path: PathBuf) -> Result<Self> {
         let config_string =
             std::fs::read_to_string(&config_path).map_err(|err| Error::ConfigFileRead {
                 config_path: config_path.clone(),
                 source: err,
             })?;
-        Self::from_string(root_dir, config_path, &config_string, true)
+        Self::from_string(config_path, &config_string, true)
     }
 
     /// Loads a config file without validation for use in tests.
     #[cfg(test)]
     pub fn from_string_for_test(config_string: &str) -> Result<Self> {
         Self::from_string(
-            "/virtual/root".into(),
             "/virtual/root/virtual_config.json".into(),
             config_string,
             false,
         )
     }
 
     /// `validate_fs` disables all filesystem checks for existence of files
-    fn from_string(
-        root_dir: PathBuf,
-        config_path: PathBuf,
-        config_string: &str,
-        validate_fs: bool,
-    ) -> Result<Self> {
+    fn from_string(config_path: PathBuf, config_string: &str, validate_fs: bool) -> Result<Self> {
         let config_file: ConfigFile =
             serde_json::from_str(&config_string).map_err(|err| Error::ConfigFileParse {
                 config_path: config_path.clone(),
@@ -136,6 +130,14 @@ impl Config {
                 Ok((project_name, project_config))
             })
             .collect::<Result<HashMap<_, _>>>()?;
+
+        let config_file_dir = config_path.parent().unwrap();
+        let root_dir = if let Some(config_root) = config_file.root {
+            config_file_dir.join(config_root).canonicalize().unwrap()
+        } else {
+            config_file_dir.to_owned()
+        };
+
         let config = Self {
             root_dir,
             sources: config_file.sources,
@@ -315,6 +317,11 @@ pub enum SchemaLocation {
 #[derive(Debug, Deserialize)]
 #[serde(deny_unknown_fields, rename_all = "camelCase")]
 struct ConfigFile {
+    /// Root directory relative to the config file. Defaults to the directory
+    /// where the config is located.
+    #[serde(default)]
+    root: Option<PathBuf>,
+
     #[serde(default)]
     header: Vec<String>,
     #[serde(default)]

compiler/crates/relay-compiler/src/main.rs

@@ -23,9 +23,6 @@ struct Opt {
 
     /// Path to the compiler config file
     config: PathBuf,
-
-    /// Root directory of the project
-    root: PathBuf,
 }
 
 #[tokio::main]
@@ -34,7 +31,7 @@ async fn main() {
 
     let opt = Opt::from_args();
 
-    let config = match Config::load(opt.root, opt.config) {
+    let config = match Config::load(opt.config) {
         Ok(config) => config,
         Err(err) => {
             error!("{}", err);

compiler/crates/relay-lsp/src/server.rs

@@ -151,8 +151,7 @@ fn load_config() -> Config {
         "{}/fbsource/fbcode/relay/config/config.test.json",
         home
     ));
-    let root_dir = PathBuf::from(format!("{}/fbsource", home));
-    let mut config = Config::load(root_dir, config_path).unwrap();
+    let mut config = Config::load(config_path).unwrap();
     // Don't write artifacts by default
     config.write_artifacts = false;
     config