check for parse errors and do not format if errors are found

Author: zth

analysis/src/Commands.ml

@@ -212,16 +212,20 @@ let rename ~path ~line ~col ~newName =
 
 let format ~path =
   if Filename.check_suffix path ".res" then
-    let {Res_driver.parsetree = structure; comments} =
+    let {Res_driver.parsetree = structure; comments; diagnostics} =
       Res_driver.parsingEngine.parseImplementation ~forPrinter:true
         ~filename:path
     in
-    Res_printer.printImplementation !Res_cli.ResClflags.width structure comments
+    if List.length diagnostics > 0 then ""
+    else
+      Res_printer.printImplementation !Res_cli.ResClflags.width structure
+        comments
   else if Filename.check_suffix path ".resi" then
-    let {Res_driver.parsetree = signature; comments} =
+    let {Res_driver.parsetree = signature; comments; diagnostics} =
       Res_driver.parsingEngine.parseInterface ~forPrinter:true ~filename:path
     in
-    Res_printer.printInterface !Res_cli.ResClflags.width signature comments
+    if List.length diagnostics > 0 then ""
+    else Res_printer.printInterface !Res_cli.ResClflags.width signature comments
   else ""
 
 let test ~path =

server/src/server.ts

@@ -466,7 +466,7 @@ function format(msg: p.RequestMessage): Array<m.Message> {
 
     // code will always be defined here, even though technically it can be undefined
     let code = getOpenedFileContent(params.textDocument.uri);
-    let formattedResult = utils.formatUsingValidBscNativePath(
+    let formattedResult = utils.formatCode(
       code,
       bscNativePath,
       extension === c.resiExt

server/src/utils.ts

@@ -93,7 +93,7 @@ type execResult =
       kind: "error";
       error: string;
     };
-export let formatUsingValidBscNativePath = (
+export let formatCode = (
   code: string,
   bscNativePath: p.DocumentUri | null,
   isInterface: boolean
@@ -124,6 +124,16 @@ export let formatUsingValidBscNativePath = (
         false
       );
 
+      // The formatter returning an empty string means it couldn't format the
+      // sources, probably because of errors. In that case, we bail from
+      // formatting by returning the unformatted content.
+      if (result === "") {
+        return {
+          kind: "success",
+          result: code,
+        };
+      }
+
       return {
         kind: "success",
         result,