Fix issue with invalid code when emitting typeof with a function.

Fixes #7641

Author: cristianoc

CHANGELOG.md

@@ -29,6 +29,11 @@
 
 - Add experimental command to `rescript-tools` for extracting all ReScript code blocks from markdown, either a md-file directly, or inside of docstrings in ReScript code. https://github.com/rescript-lang/rescript/pull/7623
 
+#### :bug: Bug fix
+
+- Fix `typeof` parens on functions. https://github.com/rescript-lang/rescript/pull/7643
+
+
 # 12.0.0-beta.1
 
 #### :rocket: New Feature

compiler/core/js_dump.ml

@@ -798,9 +798,14 @@ and expression_desc cxt ~(level : int) f x : cxt =
         P.string f " in ";
         expression ~level:0 cxt f obj)
   | Typeof e ->
+    let is_fun =
+      match e.expression_desc with
+      | Fun _ -> true
+      | _ -> false
+    in
     P.string f "typeof";
     P.space f;
-    expression ~level:13 cxt f e
+    P.cond_paren_group f is_fun (fun _ -> expression ~level:13 cxt f e)
   | Bin
       ( Minus,
         {

tests/tests/src/core/Test.mjs

@@ -45,9 +45,14 @@ function run(loc, left, comparator, right) {
   console.log(obj.stack.replace(/\n    /g, "\n  ").replace(/^Error\n/, "").replace(/^.+\n/, "").replace(/\n  at .+\(node:internal.+\n?/g, ""));
 }
 
+console.log(typeof (prim => require(prim)));
+
+let TypeofParensOnFun = {};
+
 export {
   dirname,
   print,
   run,
+  TypeofParensOnFun,
 }
 /* dirname Not a pure module */

tests/tests/src/core/Test.res

@@ -48,3 +48,9 @@ ${codeFrame}
     ->Console.log
   }
 }
+
+module TypeofParensOnFun = {
+  @val external require: string => {..} = "require"
+
+  Console.log(Type.typeof(require))
+}