Bring ad-hoc simplification of && generation up to speed.

Author: cristianoc

compiler/core/js_exp_make.ml

@@ -673,6 +673,14 @@ let rec filter_bool (e : t) ~j ~b =
     match (filter_bool e1 ~j ~b, filter_bool e2 ~j ~b) with
     | None, _ | _, None -> None
     | Some e1, Some e2 -> Some {e with expression_desc = Bin (Or, e1, e2)})
+  | Bin (EqEqEq, {expression_desc = Var i}, {expression_desc = Bool b1})
+  | Bin (EqEqEq, {expression_desc = Bool b1}, {expression_desc = Var i})
+    when Js_op_util.same_vident i j ->
+    if b1 = b then None else Some e
+  | Bin (NotEqEq, {expression_desc = Var i}, {expression_desc = Bool b1})
+  | Bin (NotEqEq, {expression_desc = Bool b1}, {expression_desc = Var i})
+    when Js_op_util.same_vident i j ->
+    if b1 <> b then None else Some e
   | Bin
       ( NotEqEq,
         {expression_desc = Typeof {expression_desc = Var i}},

tests/tests/src/UntaggedVariants.mjs

@@ -386,9 +386,9 @@ function check$1(s) {
       return;
     }
     let match = s[0];
-    if ((match === null || match === true || match === false || match === undefined) && match === true) {
+    if (match === true) {
       let match$1 = s[1];
-      if ((match$1 === null || match$1 === true || match$1 === false || match$1 === undefined) && match$1 === false) {
+      if (match$1 === false) {
         let match$2 = s[2];
         if (match$2 === null || match$2 === true || match$2 === false || match$2 === undefined) {
           console.log("Nope...");