fix corner case with NaN (#4437)

fixes #4436

lib/compress.js

@@ -9297,10 +9297,9 @@ merge(Compressor.prototype, {
     OPT(AST_Infinity, function(self, compressor) {
         var lhs = is_lhs(compressor.self(), compressor.parent());
         if (lhs && is_atomic(lhs, self)) return self;
-        if (compressor.option("keep_infinity")
+        if (compressor.option("keep_infinity") && !lhs && !find_scope(compressor).find_variable("Infinity")) {
-            && !(lhs && !is_atomic(lhs, self))
-            && !find_scope(compressor).find_variable("Infinity"))
             return self;
+        }
         return make_node(AST_Binary, self, {
             operator: "/",
             left: make_node(AST_Number, self, {
@@ -9314,18 +9313,17 @@ merge(Compressor.prototype, {
 
     OPT(AST_NaN, function(self, compressor) {
         var lhs = is_lhs(compressor.self(), compressor.parent());
-        if (lhs && !is_atomic(lhs, self) || find_scope(compressor).find_variable("NaN")) {
+        if (lhs && is_atomic(lhs, self)) return self;
-            return make_node(AST_Binary, self, {
+        if (!lhs && !find_scope(compressor).find_variable("NaN")) return self;
-                operator: "/",
+        return make_node(AST_Binary, self, {
-                left: make_node(AST_Number, self, {
+            operator: "/",
-                    value: 0
+            left: make_node(AST_Number, self, {
-                }),
+                value: 0
-                right: make_node(AST_Number, self, {
+            }),
-                    value: 0
+            right: make_node(AST_Number, self, {
-                })
+                value: 0
-            });
+            })
-        }
+        });
-        return self;
     });
 
     function is_reachable(self, defs) {

test/compress/destructured.js

@@ -2037,3 +2037,90 @@ issue_4425: {
     expect_stdout: "PASS"
     node_version: ">=8"
 }
+
+issue_4436_Infinity: {
+    options = {
+        unused: true,
+    }
+    input: {
+        console.log(function({
+            [delete Infinity]: a,
+        }) {
+            var Infinity;
+            return a;
+        }({
+            true: "FAIL",
+            false: "PASS",
+        }));
+    }
+    expect: {
+        console.log(function({
+            [delete Infinity]: a,
+        }) {
+            return a;
+        }({
+            true: "FAIL",
+            false: "PASS",
+        }));
+    }
+    expect_stdout: true
+    node_version: ">=6"
+}
+
+issue_4436_NaN: {
+    options = {
+        unused: true,
+    }
+    input: {
+        console.log(function({
+            [delete NaN]: a,
+        }) {
+            var NaN;
+            return a;
+        }({
+            true: "FAIL",
+            false: "PASS",
+        }));
+    }
+    expect: {
+        console.log(function({
+            [delete NaN]: a,
+        }) {
+            return a;
+        }({
+            true: "FAIL",
+            false: "PASS",
+        }));
+    }
+    expect_stdout: true
+    node_version: ">=6"
+}
+
+issue_4436_undefined: {
+    options = {
+        unused: true,
+    }
+    input: {
+        console.log(function({
+            [delete undefined]: a,
+        }) {
+            var undefined;
+            return a;
+        }({
+            true: "FAIL",
+            false: "PASS",
+        }));
+    }
+    expect: {
+        console.log(function({
+            [delete undefined]: a,
+        }) {
+            return a;
+        }({
+            true: "FAIL",
+            false: "PASS",
+        }));
+    }
+    expect_stdout: true
+    node_version: ">=6"
+}