Add an option to set server command line arguments. Fixes haskell#462

Author: cdsmith

package.json

@@ -144,6 +144,12 @@
           "default": "",
           "markdownDescription": "Manually set a language server executable. Can be something on the $PATH or a path to an executable itself. Works with `~,` `${HOME}` and `${workspaceFolder}`. **Deprecated scope**: This option will be set to `machine` scope in a future release, so it can be changed only globally, not per workspace."
         },
+        "haskell.serverExtraArgs": {
+          "scope": "resource",
+          "type": "string",
+          "default": "",
+          "markdownDescription": "Pass additional arguments to the language server."
+        },
         "haskell.updateBehavior": {
           "scope": "machine",
           "type": "string",

src/extension.ts

@@ -196,6 +196,11 @@ async function activateServerForFolder(context: ExtensionContext, uri: Uri, fold
     args = args.concat(['-l', logFile]);
   }
 
+  let extraArgs: string = workspace.getConfiguration('haskell', uri).serverExtraArgs;
+  if (extraArgs !== null) {
+    args = args.concat(extraArgs.split(' '));
+  }
+
   // If we're operating on a standalone file (i.e. not in a folder) then we need
   // to launch the server in a reasonable current directory. Otherwise the cradle
   // guessing logic in hie-bios will be wrong!