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fix corner case in conditionals (#3809)

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fixes #3808
This commit is contained in:
Alex Lam S.L
2020-04-21 23:30:08 +01:00
committed by GitHub
parent 925a0ca1a0
commit 9577c8c1b7
2 changed files with 52 additions and 6 deletions
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24
lib/compress.js
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@@ -4933,9 +4933,21 @@ merge(Compressor.prototype, {
});
def(AST_Sequence, function(compressor, first_in_statement) {
var expressions = trim(this.expressions, compressor, first_in_statement);
if (expressions === this.expressions) return this;
if (!expressions) return null;
return make_sequence(this, expressions);
var end = expressions.length - 1;
var assign, cond, lhs;
if (compressor.option("conditionals")
&& end > 0
&& (assign = expressions[end - 1]) instanceof AST_Assign
&& assign.operator == "="
&& (lhs = assign.left) instanceof AST_SymbolRef
&& (cond = to_conditional_assignment(compressor, lhs.definition(), assign.right, expressions[end]))) {
assign = assign.clone();
assign.right = cond;
expressions = expressions.slice(0, -2);
expressions.push(assign);
}
return expressions === this.expressions ? this : make_sequence(this, expressions);
});
def(AST_Sub, function(compressor, first_in_statement) {
if (this.expression.may_throw_on_access(compressor)) return this;
@@ -6390,16 +6402,16 @@ merge(Compressor.prototype, {
function merge_conditional_assignments() {
if (!compressor.option("conditionals")) return;
for (var i = 0; i < end; i++) {
var assign = expressions[i];
for (var i = 1; i < end; i++) {
var assign = expressions[i - 1];
if (!(assign instanceof AST_Assign)) continue;
if (assign.operator != "=") continue;
if (!(assign.left instanceof AST_SymbolRef)) continue;
var def = assign.left.definition();
var cond = to_conditional_assignment(compressor, def, assign.right, expressions[i + 1]);
var cond = to_conditional_assignment(compressor, def, assign.right, expressions[i]);
if (!cond) continue;
assign.right = cond;
expressions.splice(i + 1, 1);
expressions.splice(i, 1);
end--;
}
}