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fix corner case in collapse_vars (#3898)

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fixes #3897
This commit is contained in:
Alex Lam S.L
2020-05-14 18:09:54 +01:00
committed by GitHub
parent 938368ba21
commit 5ef7060098
2 changed files with 40 additions and 4 deletions
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10
lib/compress.js
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@@ -1855,7 +1855,12 @@ merge(Compressor.prototype, {
}
function foldable(expr) {
var lhs_ids = Object.create(null);
var marker = new TreeWalker(function(node) {
if (node instanceof AST_SymbolRef) lhs_ids[node.definition().id] = true;
});
while (expr instanceof AST_Assign && expr.operator == "=") {
expr.left.walk(marker);
expr = expr.right;
}
if (expr instanceof AST_SymbolRef) {
@@ -1871,12 +1876,9 @@ merge(Compressor.prototype, {
if (!(lhs instanceof AST_SymbolRef)) return false;
if (!invariant(expr)) return false;
var circular;
var def = lhs.definition();
expr.walk(new TreeWalker(function(node) {
if (circular) return true;
if (node instanceof AST_SymbolRef && node.definition() === def) {
circular = true;
}
if (node instanceof AST_SymbolRef && lhs_ids[node.definition().id]) circular = true;
}));
return !circular && rhs_exact_match;