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enhance unused (#3584)
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@alexlamsl
alexlamsl committed Nov 13, 2019
1 parent ab15c40 commit 4bd36dc
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Showing 3 changed files with 78 additions and 51 deletions.
81 changes: 47 additions & 34 deletions lib/compress.js
View file
Expand Up @@ -3727,10 +3727,20 @@ merge(Compressor.prototype, {
});
}
if (value) {
props.push(value);
return maintain_this_binding(compressor, parent, node, make_sequence(node, props.map(function(prop) {
return prop.transform(tt);
})));
if (parent instanceof AST_Sequence && parent.tail_node() !== node) {
value = value.drop_side_effect_free(compressor);
}
if (value) props.push(value);
switch (props.length) {
case 0:
return MAP.skip;
case 1:
return maintain_this_binding(compressor, parent, node, props[0].transform(tt));
default:
return make_sequence(node, props.map(function(prop) {
return prop.transform(tt);
}));
}
}
}
}
Expand Down Expand Up @@ -3874,37 +3884,10 @@ merge(Compressor.prototype, {
});
}
}
// certain combination of unused name + side effect leads to:
// https://github.com/mishoo/UglifyJS2/issues/44
// https://github.com/mishoo/UglifyJS2/issues/1830
// https://github.com/mishoo/UglifyJS2/issues/1838
// https://github.com/mishoo/UglifyJS2/issues/3371
// that's an invalid AST.
// We fix it at this stage by moving the `var` outside the `for`.
if (node instanceof AST_For) {
descend(node, this);
var block;
if (node.init instanceof AST_BlockStatement) {
block = node.init;
node.init = block.body.pop();
block.body.push(node);
}
if (node.init instanceof AST_Defun) {
if (!block) {
block = make_node(AST_BlockStatement, node, {
body: [ node ]
});
}
block.body.splice(-1, 0, node.init);
node.init = null;
} else if (node.init instanceof AST_SimpleStatement) {
node.init = node.init.body;
} else if (is_empty(node.init)) {
node.init = null;
}
return !block ? node : in_list ? MAP.splice(block.body) : block;
}
if (node instanceof AST_LabeledStatement && node.body instanceof AST_For) {
// Certain combination of unused name + side effect leads to invalid AST:
// https://github.com/mishoo/UglifyJS2/issues/1830
// We fix it at this stage by moving the label inwards, back to the `for`.
descend(node, this);
if (node.body instanceof AST_BlockStatement) {
var block = node.body;
Expand Down Expand Up @@ -3934,6 +3917,36 @@ merge(Compressor.prototype, {
col : sym.start.col
};
}
}, function(node, in_list) {
if (node instanceof AST_For) {
// Certain combination of unused name + side effect leads to invalid AST:
// https://github.com/mishoo/UglifyJS2/issues/44
// https://github.com/mishoo/UglifyJS2/issues/1838
// https://github.com/mishoo/UglifyJS2/issues/3371
// We fix it at this stage by moving the `var` outside the `for`.
var block;
if (node.init instanceof AST_BlockStatement) {
block = node.init;
node.init = block.body.pop();
block.body.push(node);
}
if (node.init instanceof AST_Defun) {
if (!block) {
block = make_node(AST_BlockStatement, node, {
body: [ node ]
});
}
block.body.splice(-1, 0, node.init);
node.init = null;
} else if (node.init instanceof AST_SimpleStatement) {
node.init = node.init.body;
} else if (is_empty(node.init)) {
node.init = null;
}
return !block ? node : in_list ? MAP.splice(block.body) : block;
} else if (node instanceof AST_Sequence) {
if (node.expressions.length == 1) return node.expressions[0];
}
});
tt.push(compressor.parent());
self.transform(tt);
Expand Down
46 changes: 30 additions & 16 deletions test/compress/drop-unused.js
View file
Expand Up @@ -1019,14 +1019,21 @@ delete_assign_1: {
console.log(delete (a = 0 / 0));
}
expect: {
console.log((void 0, !0));
console.log((void 0, !0));
console.log((1 / 0, !0));
console.log((1 / 0, !0));
console.log((NaN, !0));
console.log((NaN, !0));
console.log(!0);
console.log(!0);
console.log(!0);
console.log(!0);
console.log(!0);
console.log(!0);
}
expect_stdout: true
expect_stdout: [
"true",
"true",
"true",
"true",
"true",
"true",
]
}

delete_assign_2: {
Expand All @@ -1047,14 +1054,21 @@ delete_assign_2: {
console.log(delete (a = 0 / 0));
}
expect: {
console.log((void 0, !0));
console.log((void 0, !0));
console.log((Infinity, !0));
console.log((1 / 0, !0));
console.log((NaN, !0));
console.log((NaN, !0));
console.log(!0);
console.log(!0);
console.log(!0);
console.log(!0);
console.log(!0);
console.log(!0);
}
expect_stdout: true
expect_stdout: [
"true",
"true",
"true",
"true",
"true",
"true",
]
}

drop_var: {
Expand Down Expand Up @@ -1635,7 +1649,7 @@ double_assign_2: {
}
expect: {
for (var i = 0; i < 2; i++)
void 0, a = {}, console.log(a);
a = {}, console.log(a);
var a;
}
}
Expand Down Expand Up @@ -1716,7 +1730,7 @@ issue_2768: {
}
expect: {
var a = "FAIL";
var c = (d = a, 0, void (d && (a = "PASS")));
var c = (d = a, void (d && (a = "PASS")));
var d;
console.log(a, typeof c);
}
Expand Down
2 changes: 1 addition & 1 deletion test/compress/functions.js
View file
Expand Up @@ -2346,7 +2346,7 @@ issue_3274: {
}
expect: {
(function() {
for (var c; void 0, (c = 1..p) != c;)
for (var c; (c = 1..p) != c;)
console.log("FAIL");
console.log("PASS");
})();
Expand Down

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