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fix corner cases with new.target (#4784)
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@alexlamsl
alexlamsl committed Mar 16, 2021
1 parent 77c9116 commit 352a944
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Showing 5 changed files with 126 additions and 30 deletions.
6 changes: 5 additions & 1 deletion lib/ast.js
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Expand Up @@ -55,9 +55,10 @@ function DEFNODE(type, props, methods, base) {
props.forEach(function(prop) {
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("}}");
code.push("}");
var ctor = new Function(code.join(""))();
if (proto) {
ctor.prototype = proto;
Expand Down Expand Up @@ -1818,6 +1819,9 @@ var AST_This = DEFNODE("This", null, {

var AST_NewTarget = DEFNODE("NewTarget", null, {
$documentation: "The `new.target` symbol",
initialize: function() {
this.name = "new.target";
},
_validate: function() {
if (this.name !== "new.target") throw new Error('name must be "new.target": ' + this.name);
},
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17 changes: 15 additions & 2 deletions lib/compress.js
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Expand Up @@ -916,7 +916,7 @@ merge(Compressor.prototype, {
tw.find_parent(AST_Scope).may_call_this();
var exp = this.expression;
if (exp instanceof AST_LambdaExpression) {
var iife = !exp.name;
var iife = is_iife_single(this);
this.args.forEach(function(arg) {
arg.walk(tw);
if (arg instanceof AST_Spread) iife = false;
Expand Down Expand Up @@ -1591,6 +1591,19 @@ merge(Compressor.prototype, {
return node instanceof AST_LambdaExpression ? !is_arrow(node) : is_iife_call(node);
}

function is_iife_single(call) {
var exp = call.expression;
if (exp.name) return false;
if (!(call instanceof AST_New)) return true;
var found = false;
exp.walk(new TreeWalker(function(node) {
if (found) return true;
if (node instanceof AST_NewTarget) return found = true;
if (node instanceof AST_Scope && node !== exp) return true;
}));
return !found;
}

function is_undeclared_ref(node) {
return node instanceof AST_SymbolRef && node.definition().undeclared;
}
Expand Down Expand Up @@ -2127,11 +2140,11 @@ merge(Compressor.prototype, {
var iife, fn = compressor.self();
if (fn instanceof AST_LambdaExpression
&& !is_generator(fn)
&& !fn.name
&& !fn.uses_arguments
&& !fn.pinned()
&& (iife = compressor.parent()) instanceof AST_Call
&& iife.expression === fn
&& is_iife_single(iife)
&& all(iife.args, function(arg) {
return !(arg instanceof AST_Spread);
})) {
Expand Down
29 changes: 12 additions & 17 deletions lib/parse.js
View file
Expand Up @@ -1737,28 +1737,23 @@ function parse($TEXT, options) {
var new_ = function(allow_calls) {
var start = S.token;
expect_token("operator", "new");
var call;
if (is("punc", ".") && is_token(peek(), "name", "target")) {
next();
next();
return new AST_NewTarget({
name: "new.target",
start: start,
end: prev(),
});
}
var newexp = expr_atom(false), args;
if (is("punc", "(")) {
next();
args = expr_list(")", !options.strict);
call = new AST_NewTarget();
} else {
args = [];
var exp = expr_atom(false), args;
if (is("punc", "(")) {
next();
args = expr_list(")", !options.strict);
} else {
args = [];
}
call = new AST_New({ expression: exp, args: args });
}
var call = new AST_New({
start : start,
expression : newexp,
args : args,
end : prev()
});
call.start = start;
call.end = prev();
return subscripts(call, allow_calls);
};

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96 changes: 88 additions & 8 deletions test/compress/functions.js
View file
Expand Up @@ -5753,22 +5753,102 @@ issue_4725_2: {
node_version: ">=4"
}

new_target: {
new_target_1: {
input: {
console.log(typeof new function() {
return new.target;
}, function() {
new function f() {
console.log(new.target === f);
}();
console.log(function() {
return new.target;
}());
}
expect: {
console.log(typeof new function() {
return new.target;
}(), function() {
new function f() {
console.log(new.target === f);
}();
console.log(function() {
return new.target;
}());
}
expect_stdout: "function undefined"
expect_stdout: [
"true",
"undefined",
]
node_version: ">=6"
}

new_target_2: {
input: {
new function(a) {
if (!new.target)
console.log("FAIL");
else if (a)
console.log("PASS");
else
new new.target(new.target.length);
}();
}
expect: {
new function(a) {
if (!new.target)
console.log("FAIL");
else if (a)
console.log("PASS");
else
new new.target(new.target.length);
}();
}
expect_stdout: "PASS"
node_version: ">=6"
}

new_target_collapse_vars: {
options = {
collapse_vars: true,
unused: true,
}
input: {
new function(a) {
if (a)
console.log("PASS");
else
new new.target(new.target.length);
}(0);
}
expect: {
new function(a) {
if (a)
console.log("PASS");
else
new new.target(new.target.length);
}(0);
}
expect_stdout: "PASS"
node_version: ">=6"
}

new_target_reduce_vars: {
options = {
evaluate: true,
reduce_vars: true,
}
input: {
new function(a) {
if (a)
console.log("PASS");
else
new new.target(new.target.length);
}(0);
}
expect: {
new function(a) {
if (a)
console.log("PASS");
else
new new.target(new.target.length);
}(0);
}
expect_stdout: "PASS"
node_version: ">=6"
}

Expand Down
8 changes: 6 additions & 2 deletions test/ufuzz/index.js
View file
Expand Up @@ -149,6 +149,7 @@ var SUPPORT = function(matrix) {
for_of: "for (var a of []);",
generator: "function* f(){}",
let: "let a;",
new_target: "function f() { new.target; }",
nullish: "0 ?? 0",
rest: "var [...a] = [];",
rest_object: "var {...a} = {};",
Expand Down Expand Up @@ -1401,13 +1402,16 @@ function _createExpression(recurmax, noComma, stmtDepth, canThrow) {
createBlockVariables(recurmax, stmtDepth, canThrow, function(defns) {
s.push(
instantiate + makeFunction(name) + "(" + createParams(save_async, save_generator) + "){",
strictMode(),
defns()
strictMode()
);
var add_new_target = SUPPORT.new_target && VALUES.indexOf("new.target") < 0;
if (add_new_target) VALUES.push("new.target");
s.push(defns());
if (instantiate) for (var i = rng(4); --i >= 0;) {
s.push((in_class ? "if (this) " : "") + createThisAssignment(recurmax, stmtDepth, canThrow));
}
s.push(_createStatements(rng(5) + 1, recurmax, canThrow, CANNOT_BREAK, CANNOT_CONTINUE, CAN_RETURN, stmtDepth));
if (add_new_target) VALUES.splice(VALUES.indexOf("new.target"), 1);
});
generator = save_generator;
async = save_async;
Expand Down

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