add projectUsesOutFile field to protocol.CompileOnSaveAffectedFileListSingleProject (#13915)

src/server/protocol.ts

@@ -1239,6 +1239,11 @@ namespace ts.server.protocol {
          * List of files names that should be recompiled
          */
         fileNames: string[];
+
+        /**
+         * true if project uses outFile or out compiler option
+         */
+        projectUsesOutFile: boolean;
     }
 
     /**

src/server/session.ts

@@ -1040,7 +1040,8 @@ namespace ts.server {
                 if (project.compileOnSaveEnabled && project.languageServiceEnabled) {
                     result.push({
                         projectFileName: project.getProjectName(),
-                        fileNames: project.getCompileOnSaveAffectedFileList(info)
+                        fileNames: project.getCompileOnSaveAffectedFileList(info),
+                        projectUsesOutFile: !!project.getCompilerOptions().outFile || !!project.getCompilerOptions().out
                     });
                 }
             }