fix corner cases in `parse` & `unused` (#5000)

5 files changed, 39 insertions, 40 deletions

diff --git a/bin/uglifyjs b/bin/uglifyjs
index 2d03d99a..197e42bf 100755
--- a/bin/uglifyjs
+++ b/bin/uglifyjs
@@ -344,9 +344,9 @@ function run() {
                     var list = annotations[node.start.file];
                     var pure = list[node.start.pos];
                     if (!pure) {
-                        var pos = node.start.parens;
-                        if (pos) for (var i = 0; !pure && i < pos.length; i++) {
-                            pure = list[pos[i]];
+                        var tokens = node.start.parens;
+                        if (tokens) for (var i = 0; !pure && i < tokens.length; i++) {
+                            pure = list[tokens[i].pos];
                         }
                     }
                     if (pure) node.pure = pure;
diff --git a/lib/ast.js b/lib/ast.js
index 590c09bf..28e437f7 100644
--- a/lib/ast.js
+++ b/lib/ast.js
@@ -56,35 +56,31 @@ function DEFNODE(type, props, methods, base) {
         code.push("this.", prop, "=props.", prop, ";");
     });
     code.push("}");
-    var proto = base && new base;
-    if (proto && proto.initialize || methods && methods.initialize) code.push("this.initialize();");
-    code.push("}");
+    var proto = Object.create(base && base.prototype);
+    if (methods.initialize || proto.initialize) code.push("this.initialize();");
+    code.push("};");
     var ctor = new Function(code.join(""))();
-    if (proto) {
-        ctor.prototype = proto;
+    ctor.prototype = proto;
+    ctor.prototype.CTOR = ctor;
+    ctor.prototype.TYPE = ctor.TYPE = type;
+    if (base) {
         ctor.BASE = base;
+        base.SUBCLASSES.push(ctor);
     }
-    if (base) base.SUBCLASSES.push(ctor);
-    ctor.prototype.CTOR = ctor;
-    ctor.PROPS = props || null;
+    ctor.DEFMETHOD = function(name, method) {
+        this.prototype[name] = method;
+    };
+    ctor.PROPS = props;
     ctor.SELF_PROPS = self_props;
     ctor.SUBCLASSES = [];
-    if (type) {
-        ctor.prototype.TYPE = ctor.TYPE = type;
-    }
-    if (methods) for (var name in methods) if (HOP(methods, name)) {
+    for (var name in methods) if (HOP(methods, name)) {
         if (/^\$/.test(name)) {
             ctor[name.substr(1)] = methods[name];
         } else {
-            ctor.prototype[name] = methods[name];
+            ctor.DEFMETHOD(name, methods[name]);
         }
     }
-    ctor.DEFMETHOD = function(name, method) {
-        this.prototype[name] = method;
-    };
-    if (typeof exports !== "undefined") {
-        exports["AST_" + type] = ctor;
-    }
+    if (typeof exports !== "undefined") exports["AST_" + type] = ctor;
     return ctor;
 }
 
diff --git a/lib/compress.js b/lib/compress.js
index a9671257..275d2980 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -1510,7 +1510,7 @@ merge(Compressor.prototype, {
     function is_lhs_read_only(lhs, compressor) {
         if (lhs instanceof AST_ObjectIdentity) return true;
         if (lhs instanceof AST_PropAccess) {
-            if (lhs.property == "__proto__") return true;
+            if (lhs.property === "__proto__") return true;
             lhs = lhs.expression;
             if (lhs instanceof AST_SymbolRef) {
                 if (lhs.is_immutable()) return false;
@@ -3842,7 +3842,7 @@ merge(Compressor.prototype, {
         def(AST_Object, function(compressor, force) {
             return is_strict(compressor, force) && !all(this.properties, function(prop) {
                 if (!(prop instanceof AST_ObjectKeyVal)) return false;
-                return !(prop.key == "__proto__" && prop.value._dot_throw(compressor, force));
+                return !(prop.key === "__proto__" && prop.value._dot_throw(compressor, force));
             });
         });
         def(AST_ObjectIdentity, function(compressor, force) {
@@ -6727,7 +6727,7 @@ merge(Compressor.prototype, {
                 return insert_statements(body, node, in_list);
             }
             if (node instanceof AST_Import) {
-                if (node.properties && node.properties == 0) node.properties = null;
+                if (node.properties && node.properties.length == 0) node.properties = null;
                 return node;
             }
             if (node instanceof AST_Sequence) {
@@ -11809,7 +11809,7 @@ merge(Compressor.prototype, {
             var props = expr.properties;
             for (var i = props.length; --i >= 0;) {
                 var prop = props[i];
-                if (prop.key != key) continue;
+                if (prop.key !== key) continue;
                 if (!all(props, can_hoist_property)) break;
                 if (!safe_to_flatten(prop.value, compressor)) break;
                 props = props.map(function(prop) {
diff --git a/lib/parse.js b/lib/parse.js
index 463b2103..eb2dc01a 100644
--- a/lib/parse.js
+++ b/lib/parse.js
@@ -1334,21 +1334,19 @@ function parse($TEXT, options) {
         if (is("punc", "{")) {
             body = block_();
             value = null;
-            if (S.input.has_directive("use strict")) {
-                argnames.forEach(strict_verify_symbol);
-            }
         } else {
             body = [];
             handle_regexp();
             value = maybe_assign();
         }
+        var is_strict = S.input.has_directive("use strict");
         S.input.pop_directives_stack();
         --S.in_function;
         S.in_loop = loop;
         S.labels = labels;
         S.in_generator = was_gen;
         S.in_async = was_async;
-        return new (async ? AST_AsyncArrow : AST_Arrow)({
+        var node = new (async ? AST_AsyncArrow : AST_Arrow)({
             start: start,
             argnames: argnames,
             rest: rest,
@@ -1356,6 +1354,8 @@ function parse($TEXT, options) {
             value: value,
             end: prev(),
         });
+        if (is_strict) node.each_argname(strict_verify_symbol);
+        return node;
     }
 
     var function_ = function(ctor) {
@@ -1388,23 +1388,24 @@ function parse($TEXT, options) {
         S.in_loop = 0;
         S.labels = [];
         var body = block_();
-        if (S.input.has_directive("use strict")) {
-            if (name) strict_verify_symbol(name);
-            argnames.forEach(strict_verify_symbol);
-            if (argnames.rest) strict_verify_symbol(argnames.rest);
-        }
+        var is_strict = S.input.has_directive("use strict");
         S.input.pop_directives_stack();
         --S.in_function;
         S.in_loop = loop;
         S.labels = labels;
         S.in_generator = was_gen;
         S.in_async = was_async;
-        return new ctor({
+        var node = new ctor({
             name: name,
             argnames: argnames,
             rest: argnames.rest || null,
             body: body
         });
+        if (is_strict) {
+            if (name) strict_verify_symbol(name);
+            node.each_argname(strict_verify_symbol);
+        }
+        return node;
     };
 
     function if_() {
diff --git a/test/compress/imports.js b/test/compress/imports.js
index d0e6af56..0accb3ec 100644
--- a/test/compress/imports.js
+++ b/test/compress/imports.js
@@ -94,13 +94,15 @@ drop_unused: {
     }
     input: {
         import a, * as b from "foo";
-        import { c, bar as d } from "baz";
-        console.log(c);
+        import { c } from "bar";
+        import { d, _ as e } from "baz";
+        console.log(d);
     }
     expect: {
         import "foo";
-        import { c as c } from "baz";
-        console.log(c);
+        import "bar";
+        import { d as d } from "baz";
+        console.log(d);
     }
 }