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fix chained assignment with unused (#1540)

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When #1450 optimises `a=b=42`, it stops after the first variable even if both are unused.

fixes #1539
This commit is contained in:
Alex Lam S.L
2017-03-03 04:45:20 +08:00
committed by GitHub
parent 4d63d4f5b3
commit 17b81350d4
2 changed files with 31 additions and 7 deletions
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17
lib/compress.js
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@@ -1801,14 +1801,17 @@ merge(Compressor.prototype, {
}
return node;
}
if (drop_vars && assign_as_unused
&& node instanceof AST_Assign
&& node.operator == "="
&& node.left instanceof AST_SymbolRef) {
var def = node.left.definition();
if (!(def.id in in_use_ids) && self.variables.get(def.name) === def) {
return node.right;
if (drop_vars && assign_as_unused) {
var n = node;
while (n instanceof AST_Assign
&& n.operator == "="
&& n.left instanceof AST_SymbolRef) {
var def = n.left.definition();
if (def.id in in_use_ids
|| self.variables.get(def.name) !== def) break;
n = n.right;
}
if (n !== node) return n;
}
if (node instanceof AST_For) {
descend(node, this);