Improve monorepo/workspace bsc

Author: chenglou

server/src/constants.ts

@@ -9,7 +9,6 @@ export let bscExePartialPath = path.join(
   process.platform,
   "bsc.exe"
 );
-export let bscNodePartialPath = path.join("node_modules", ".bin", "bsc");
 
 // can't use the native bsb since we might need the watcher -w flag, which is only in the js wrapper
 // export let bsbPartialPath = path.join('node_modules', 'bs-platform', process.platform, 'bsb.exe');

server/src/server.ts

@@ -431,30 +431,15 @@ process.on("message", (msg: m.Message) => {
           process.send!(fakeSuccessResponse);
           process.send!(response);
         } else {
-          let bscExePath = path.join(projectRootPath, c.bscExePartialPath);
-          let bscNodePath = path.join(projectRootPath, c.bscNodePartialPath);
-          // There are the native bsc.exe binaries the bs-platform package, and
-          // the javascript bsc wrapper within node_modules/.bin. The JS wrapper
-          // starts and finds the right platform-specific native binary to call.
-          // This has nontrivial overhead each formatting, so we try to directly
-          // invoke the platform-specific native binary (inside bs-platform).
-
-          // However, we won't always be able to find the bs-platform package;
-          // for example yarn workspace lifts up the dependencies packages to a
-          // directory higher (grumbles); that setup only leaves us to find
-          // node_modules/.bin (which it doesn't touch, thankfully). So for
-          // quirky npm setups, we need to have a graceful degradation and find
-          // the JS bsc wrapper. If we can't even find node_modules/.bin then we
-          // give up
-          let resolvedBscPath = fs.existsSync(bscExePath)
-            ? bscExePath
-            : fs.existsSync(bscNodePath)
-              ? bscNodePath
-              : null;
-          if (resolvedBscPath === null) {
+          // See comment on findBscExeDirUpwardFromProjectRoot for why we need
+          // to recursively search for bsc.exe upward
+          let bscExeDir = utils.findBscExeDirUpwardFromProjectRoot(
+            projectRootPath
+          );
+          if (bscExeDir === null) {
             let params: p.ShowMessageParams = {
               type: p.MessageType.Error,
-              message: `Cannot find a nearby ${c.bscExePartialPath} nor ${c.bscNodePartialPath}. It's needed for formatting.`,
+              message: `Cannot find a nearby ${c.bscExePartialPath}. It's needed for formatting.`,
             };
             let response: m.NotificationMessage = {
               jsonrpc: c.jsonrpcVersion,
@@ -464,6 +449,7 @@ process.on("message", (msg: m.Message) => {
             process.send!(fakeSuccessResponse);
             process.send!(response);
           } else {
+            let resolvedBscPath = path.join(bscExeDir, c.bscExePartialPath);
             // code will always be defined here, even though technically it can be undefined
             let code = getOpenedFileContent(params.textDocument.uri);
             let formattedResult = utils.formatUsingValidBscPath(

server/src/utils.ts

@@ -34,6 +34,33 @@ export let findProjectRootOfFile = (
 	}
 };
 
+// TODO: races here?
+// TODO: this doesn't handle file:/// scheme
+
+// We need to recursively search for bs-platform/{platform}/bsc.exe upward from
+// the project's root, because in some setups, such as yarn workspace/monorepo,
+// the node_modules/bs-platform package might be hoisted up instead of alongside
+// the project root.
+// Also, if someone's ever formatting a regular project setup's dependency
+// (which is weird but whatever), they'll at least find an upward bs-platform
+// from the dependent.
+export let findBscExeDirUpwardFromProjectRoot = (
+	dir: p.DocumentUri
+): null | p.DocumentUri => {
+	let bscPath = path.join(dir, c.bscExePartialPath);
+	if (fs.existsSync(bscPath)) {
+		return dir;
+	} else {
+		let parentDir = path.dirname(dir);
+		if (parentDir === dir) {
+			// reached the top
+			return null;
+		} else {
+			return findBscExeDirUpwardFromProjectRoot(parentDir);
+		}
+	}
+};
+
 type execResult =
 	| {
 		kind: "success";