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Account for side effects in string + expr optimization

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This commit is contained in:
kzc
2016-09-01 09:24:56 -04:00
parent 0bd8053524
commit 25fc02743a
2 changed files with 51 additions and 2 deletions
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4
lib/compress.js
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@@ -2499,8 +2499,8 @@ merge(Compressor.prototype, {
case "+":
var ll = self.left.evaluate(compressor);
var rr = self.right.evaluate(compressor);
if ((ll.length > 1 && ll[0] instanceof AST_String && ll[1]) ||
(rr.length > 1 && rr[0] instanceof AST_String && rr[1])) {
if ((ll.length > 1 && ll[0] instanceof AST_String && ll[1] && !self.right.has_side_effects(compressor)) ||
(rr.length > 1 && rr[0] instanceof AST_String && rr[1] && !self.left.has_side_effects(compressor))) {
compressor.warn("+ in boolean context always true [{file}:{line},{col}]", self.start);
return make_node(AST_True, self);
}

49
test/compress/issue-1275.js Normal file
View File

@@ -0,0 +1,49 @@
string_plus_optimization: {
options = {
side_effects : true,
evaluate : true,
conditionals : true,
comparisons : true,
dead_code : true,
booleans : true,
unused : true,
if_return : true,
join_vars : true,
cascade : true,
hoist_funs : true,
};
input: {
function foo(anything) {
function throwing_function() {
throw "nope";
}
try {
console.log('0' + throwing_function() ? "yes" : "no");
} catch (ex) {
console.log(ex);
}
console.log('0' + anything ? "yes" : "no");
console.log(anything + '0' ? "Yes" : "No");
console.log('' + anything);
console.log(anything + '');
}
foo();
}
expect: {
function foo(anything) {
function throwing_function() {
throw "nope";
}
try {
console.log('0' + throwing_function() ? "yes" : "no");
} catch (ex) {
console.log(ex);
}
console.log("yes");
console.log("Yes");
console.log('' + anything);
console.log(anything + '');
}
foo();
}
}