From 633dd64701242c7734c287b3df95dd0504b1fbfe Mon Sep 17 00:00:00 2001
From: alexlamsl <alexlamsl@gmail.com>
Date: Fri, 19 Jul 2024 14:11:45 +0300
Subject: [PATCH] enhance `comparisons`

---
 lib/compress.js              |   7 +-
 test/compress/comparisons.js | 246 ++++++++++++++++-------------------
 2 files changed, 114 insertions(+), 139 deletions(-)

diff --git a/lib/compress.js b/lib/compress.js
index b85bd8bb021..3195084a86d 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -12079,7 +12079,7 @@ Compressor.prototype.compress = function(node) {
           case "&&":
           case "||":
             // void 0 !== x && null !== x ---> null != x
-            // void 0 === x || null === x ---> null == x
+            // void 0 === x.a || null === x.a ---> null == x.a
             var left = self.left;
             if (!(left instanceof AST_Binary)) break;
             if (left.operator != (self.operator == "&&" ? "!==" : "===")) break;
@@ -12087,9 +12087,8 @@ Compressor.prototype.compress = function(node) {
             if (left.operator != self.right.operator) break;
             if (is_undefined(left.left, compressor) && self.right.left instanceof AST_Null
                 || left.left instanceof AST_Null && is_undefined(self.right.left, compressor)) {
-                var expr = left.right;
-                if (expr instanceof AST_Assign && expr.operator == "=") expr = expr.left;
-                if (expr.has_side_effects(compressor)) break;
+                var expr = extract_lhs(left.right, compressor);
+                if (!repeatable(compressor, expr)) break;
                 if (!expr.equals(self.right.right)) break;
                 left.operator = left.operator.slice(0, -1);
                 left.left = make_node(AST_Null, self);
diff --git a/test/compress/comparisons.js b/test/compress/comparisons.js
index bc860ce9a0a..2b43cc4fba4 100644
--- a/test/compress/comparisons.js
+++ b/test/compress/comparisons.js
@@ -167,48 +167,24 @@ issue_2857_1: {
         comparisons: true,
     }
     input: {
-        function f1(a) {
-            a === undefined || a === null;
-            a === undefined || a !== null;
-            a !== undefined || a === null;
-            a !== undefined || a !== null;
-            a === undefined && a === null;
-            a === undefined && a !== null;
-            a !== undefined && a === null;
-            a !== undefined && a !== null;
-        }
-        function f2(a) {
-            a === null || a === undefined;
-            a === null || a !== undefined;
-            a !== null || a === undefined;
-            a !== null || a !== undefined;
-            a === null && a === undefined;
-            a === null && a !== undefined;
-            a !== null && a === undefined;
-            a !== null && a !== undefined;
-        }
+        a === undefined || a === null;
+        a === undefined || a !== null;
+        a !== undefined || a === null;
+        a !== undefined || a !== null;
+        a === undefined && a === null;
+        a === undefined && a !== null;
+        a !== undefined && a === null;
+        a !== undefined && a !== null;
     }
     expect: {
-        function f1(a) {
-            null == a;
-            void 0 === a || null !== a;
-            void 0 !== a || null === a;
-            void 0 !== a || null !== a;
-            void 0 === a && null === a;
-            void 0 === a && null !== a;
-            void 0 !== a && null === a;
-            null != a;
-        }
-        function f2(a) {
-            null == a;
-            null === a || void 0 !== a;
-            null !== a || void 0 === a;
-            null !== a || void 0 !== a;
-            null === a && void 0 === a;
-            null === a && void 0 !== a;
-            null !== a && void 0 === a;
-            null != a;
-        }
+        null == a;
+        void 0 === a || null !== a;
+        void 0 !== a || null === a;
+        void 0 !== a || null !== a;
+        void 0 === a && null === a;
+        void 0 === a && null !== a;
+        void 0 !== a && null === a;
+        null != a;
     }
 }
 
@@ -217,28 +193,24 @@ issue_2857_2: {
         comparisons: true,
     }
     input: {
-        function f(a, p) {
-            a === undefined || a === null || p;
-            a === undefined || a !== null || p;
-            a !== undefined || a === null || p;
-            a !== undefined || a !== null || p;
-            a === undefined && a === null || p;
-            a === undefined && a !== null || p;
-            a !== undefined && a === null || p;
-            a !== undefined && a !== null || p;
-        }
+        a === null || a === undefined;
+        a === null || a !== undefined;
+        a !== null || a === undefined;
+        a !== null || a !== undefined;
+        a === null && a === undefined;
+        a === null && a !== undefined;
+        a !== null && a === undefined;
+        a !== null && a !== undefined;
     }
     expect: {
-        function f(a, p) {
-            null == a || p;
-            void 0 === a || null !== a || p;
-            void 0 !== a || null === a || p;
-            void 0 !== a || null !== a || p;
-            void 0 === a && null === a || p;
-            void 0 === a && null !== a || p;
-            void 0 !== a && null === a || p;
-            null != a || p;
-        }
+        null == a;
+        null === a || void 0 !== a;
+        null !== a || void 0 === a;
+        null !== a || void 0 !== a;
+        null === a && void 0 === a;
+        null === a && void 0 !== a;
+        null !== a && void 0 === a;
+        null != a;
     }
 }
 
@@ -247,59 +219,50 @@ issue_2857_3: {
         comparisons: true,
     }
     input: {
-        function f(a, p) {
-            a === undefined || a === null && p;
-            a === undefined || a !== null && p;
-            a !== undefined || a === null && p;
-            a !== undefined || a !== null && p;
-            a === undefined && a === null && p;
-            a === undefined && a !== null && p;
-            a !== undefined && a === null && p;
-            a !== undefined && a !== null && p;
-        }
+        a === undefined || a === null || p;
+        a === undefined || a !== null || p;
+        a !== undefined || a === null || p;
+        a !== undefined || a !== null || p;
+        a === undefined && a === null || p;
+        a === undefined && a !== null || p;
+        a !== undefined && a === null || p;
+        a !== undefined && a !== null || p;
     }
     expect: {
-        function f(a, p) {
-            void 0 === a || null === a && p;
-            void 0 === a || null !== a && p;
-            void 0 !== a || null === a && p;
-            void 0 !== a || null !== a && p;
-            void 0 === a && null === a && p;
-            void 0 === a && null !== a && p;
-            void 0 !== a && null === a && p;
-            null != a && p;
-        }
+        null == a || p;
+        void 0 === a || null !== a || p;
+        void 0 !== a || null === a || p;
+        void 0 !== a || null !== a || p;
+        void 0 === a && null === a || p;
+        void 0 === a && null !== a || p;
+        void 0 !== a && null === a || p;
+        null != a || p;
     }
 }
 
 issue_2857_4: {
     options = {
         comparisons: true,
-        conditionals: true,
     }
     input: {
-        function f(a, p) {
-            p || a === undefined || a === null;
-            p || a === undefined || a !== null;
-            p || a !== undefined || a === null;
-            p || a !== undefined || a !== null;
-            p || a === undefined && a === null;
-            p || a === undefined && a !== null;
-            p || a !== undefined && a === null;
-            p || a !== undefined && a !== null;
-        }
+        a === undefined || a === null && p;
+        a === undefined || a !== null && p;
+        a !== undefined || a === null && p;
+        a !== undefined || a !== null && p;
+        a === undefined && a === null && p;
+        a === undefined && a !== null && p;
+        a !== undefined && a === null && p;
+        a !== undefined && a !== null && p;
     }
     expect: {
-        function f(a, p) {
-            p || null == a;
-            p || void 0 === a || null !== a;
-            p || void 0 !== a || null === a;
-            p || void 0 !== a || null !== a;
-            p || void 0 === a && null === a;
-            p || void 0 === a && null !== a;
-            p || void 0 !== a && null === a;
-            p || null != a;
-        }
+        void 0 === a || null === a && p;
+        void 0 === a || null !== a && p;
+        void 0 !== a || null === a && p;
+        void 0 !== a || null !== a && p;
+        void 0 === a && null === a && p;
+        void 0 === a && null !== a && p;
+        void 0 !== a && null === a && p;
+        null != a && p;
     }
 }
 
@@ -309,32 +272,55 @@ issue_2857_5: {
         conditionals: true,
     }
     input: {
-        function f(a, p) {
-            p && a === undefined || a === null;
-            p && a === undefined || a !== null;
-            p && a !== undefined || a === null;
-            p && a !== undefined || a !== null;
-            p && a === undefined && a === null;
-            p && a === undefined && a !== null;
-            p && a !== undefined && a === null;
-            p && a !== undefined && a !== null;
-        }
+        p || a === undefined || a === null;
+        p || a === undefined || a !== null;
+        p || a !== undefined || a === null;
+        p || a !== undefined || a !== null;
+        p || a === undefined && a === null;
+        p || a === undefined && a !== null;
+        p || a !== undefined && a === null;
+        p || a !== undefined && a !== null;
     }
     expect: {
-        function f(a, p) {
-            p && void 0 === a || null === a;
-            p && void 0 === a || null !== a;
-            p && void 0 !== a || null === a;
-            p && void 0 !== a || null !== a;
-            p && void 0 === a && null === a;
-            p && void 0 === a && null !== a;
-            p && void 0 !== a && null === a;
-            p && null != a;
-        }
+        p || null == a;
+        p || void 0 === a || null !== a;
+        p || void 0 !== a || null === a;
+        p || void 0 !== a || null !== a;
+        p || void 0 === a && null === a;
+        p || void 0 === a && null !== a;
+        p || void 0 !== a && null === a;
+        p || null != a;
     }
 }
 
 issue_2857_6: {
+    options = {
+        comparisons: true,
+        conditionals: true,
+    }
+    input: {
+        p && a === undefined || a === null;
+        p && a === undefined || a !== null;
+        p && a !== undefined || a === null;
+        p && a !== undefined || a !== null;
+        p && a === undefined && a === null;
+        p && a === undefined && a !== null;
+        p && a !== undefined && a === null;
+        p && a !== undefined && a !== null;
+    }
+    expect: {
+        p && void 0 === a || null === a;
+        p && void 0 === a || null !== a;
+        p && void 0 !== a || null === a;
+        p && void 0 !== a || null !== a;
+        p && void 0 === a && null === a;
+        p && void 0 === a && null !== a;
+        p && void 0 !== a && null === a;
+        p && null != a;
+    }
+}
+
+issue_2857_7: {
     options = {
         comparisons: true,
         pure_getters: "strict",
@@ -342,27 +328,17 @@ issue_2857_6: {
     }
     input: {
         function f(a) {
-            if (({}).b === undefined || {}.b === null)
+            if ({}.b === undefined || {}.b === null)
                 return a.b !== undefined && a.b !== null;
         }
-        console.log(f({
-            a: [ null ],
-            get b() {
-                return this.a.shift();
-            }
-        }));
+        console.log(f({ b: [] }));
     }
     expect: {
         function f(a) {
             if (null == {}.b)
-                return void 0 !== a.b && null !== a.b;
+                return null != a.b;
         }
-        console.log(f({
-            a: [ null ],
-            get b() {
-                return this.a.shift();
-            }
-        }));
+        console.log(f({ b: [] }));
     }
     expect_stdout: "true"
 }