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fix corner case in arguments (#3330)

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Track modifications to `arguments[i]` under Strict Mode.

fixes #3273
This commit is contained in:
Alex Lam S.L
2019-03-13 06:59:53 +08:00
committed by GitHub
parent c6fa39b482
commit e250396d7e
2 changed files with 188 additions and 3 deletions
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24
lib/compress.js
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@@ -497,6 +497,15 @@ merge(Compressor.prototype, {
d.direct_access = true;
}
function mark_assignment_to_arguments(node) {
if (!(node instanceof AST_Sub)) return;
var expr = node.expression;
var prop = node.property;
if (expr instanceof AST_SymbolRef && expr.name == "arguments" && prop instanceof AST_Number) {
expr.definition().reassigned = true;
}
}
var suppressor = new TreeWalker(function(node) {
if (!(node instanceof AST_Symbol)) return;
var d = node.definition();
@@ -515,7 +524,10 @@ merge(Compressor.prototype, {
def(AST_Assign, function(tw, descend, compressor) {
var node = this;
var sym = node.left;
if (!(sym instanceof AST_SymbolRef)) return;
if (!(sym instanceof AST_SymbolRef)) {
mark_assignment_to_arguments(sym);
return;
}
var d = sym.definition();
var safe = safe_to_assign(tw, d, sym.scope, node.right);
d.assignments++;
@@ -758,7 +770,10 @@ merge(Compressor.prototype, {
var node = this;
if (node.operator != "++" && node.operator != "--") return;
var exp = node.expression;
if (!(exp instanceof AST_SymbolRef)) return;
if (!(exp instanceof AST_SymbolRef)) {
mark_assignment_to_arguments(exp);
return;
}
var d = exp.definition();
var safe = safe_to_assign(tw, d, exp.scope, true);
d.assignments++;
@@ -6325,7 +6340,10 @@ merge(Compressor.prototype, {
var argname = fn.argnames[index];
if (argname && compressor.has_directive("use strict")) {
var def = argname.definition();
if (!compressor.option("reduce_vars") || def.assignments || def.orig.length > 1) {
if (!compressor.option("reduce_vars")
|| expr.definition().reassigned
|| def.assignments
|| def.orig.length > 1) {
argname = null;
}
} else if (!argname && !compressor.option("keep_fargs") && index < fn.argnames.length + 5) {