parse destructuring under strict mode correctly (#4429)

lib/parse.js

@@ -1551,8 +1551,7 @@ function parse($TEXT, options) {
             next();
             return "" + tmp.value;
           case "punc":
-            if (tmp.value != "[") unexpected();
-            next();
+            expect("[");
             var key = maybe_assign();
             expect("]");
             return key;
@@ -1616,16 +1615,8 @@ function parse($TEXT, options) {
                 // allow trailing comma
                 if (!options.strict && is("punc", "}")) break;
                 var key_start = S.token;
+                if (is("punc", "[") || is_token(peek(), "punc", ":")) {
                     var key = as_property_key();
-                if (!is("punc", ":") && key_start.type == "name") {
-                    a.push(new AST_DestructuredKeyVal({
-                        start: key_start,
-                        key: key,
-                        value: _make_symbol(type, key_start),
-                        end: prev(),
-                    }));
-                    continue;
-                }
                     expect(":");
                     a.push(new AST_DestructuredKeyVal({
                         start: key_start,
@@ -1633,6 +1624,14 @@ function parse($TEXT, options) {
                         value: maybe_destructured(type),
                         end: prev(),
                     }));
+                    continue;
+                }
+                a.push(new AST_DestructuredKeyVal({
+                    start: key_start,
+                    key: key_start.value,
+                    value: as_symbol(type),
+                    end: prev(),
+                }));
             }
             next();
             return new AST_DestructuredObject({

test/input/invalid/destructured_var.js

@@ -0,0 +1,8 @@
+function f() {
+    var { eval } = null;
+}
+
+function g() {
+    "use strict";
+    var { eval } = 42;
+}

test/mocha/cli.js

@@ -573,6 +573,20 @@ describe("bin/uglifyjs", function() {
             done();
         });
     });
+    it("Should throw syntax error (var { eval })", function(done) {
+        var command = uglifyjscmd + " test/input/invalid/destructured_var.js";
+        exec(command, function(err, stdout, stderr) {
+            assert.ok(err);
+            assert.strictEqual(stdout, "");
+            assert.strictEqual(stderr.split(/\n/).slice(0, 4).join("\n"), [
+                "Parse error at test/input/invalid/destructured_var.js:7,10",
+                "    var { eval } = 42;",
+                "          ^",
+                "ERROR: Unexpected eval in strict mode"
+            ].join("\n"));
+            done();
+        });
+    });
     it("Should throw syntax error (else)", function(done) {
         var command = uglifyjscmd + " test/input/invalid/else.js";
         exec(command, function(err, stdout, stderr) {