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Prevent arguments object creation if 'arguments' function argument is present #4849

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Merged
merged 1 commit into from
Dec 7, 2021
Merged

Prevent arguments object creation if 'arguments' function argument is present #4849

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10 changes: 10 additions & 0 deletions jerry-core/parser/js/js-scanner-util.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1246,6 +1246,7 @@ scanner_filter_arguments (parser_context_t *context_p, /**< context */

if (has_arguments)
{
/* Force the lexically stored arguments object creation */
literal_pool_p->status_flags |= (SCANNER_LITERAL_POOL_ARGUMENTS_IN_ARGS | SCANNER_LITERAL_POOL_NO_ARGUMENTS);
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I would put the argument checking as a for loop here since the while (true) loop might also exit. This case is rare, so an extra loop should not cost much.

}
}
Expand Down Expand Up @@ -1306,6 +1307,14 @@ scanner_filter_arguments (parser_context_t *context_p, /**< context */
literal_p->type = type;
}

if (has_arguments && scanner_literal_is_arguments (literal_p))
{
/* 'arguments' function argument existence should prevent the arguments object construction */
new_literal_pool_p->status_flags =
(uint16_t) (new_literal_pool_p->status_flags
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Incorrect style.

& ~(SCANNER_LITERAL_POOL_ARGUMENTS_IN_ARGS | SCANNER_LITERAL_POOL_NO_ARGUMENTS));
}

if (type & (SCANNER_LITERAL_IS_DESTRUCTURED_ARG | SCANNER_LITERAL_IS_ARROW_DESTRUCTURED_ARG))
{
has_destructured_arg = true;
Expand All @@ -1328,6 +1337,7 @@ scanner_filter_arguments (parser_context_t *context_p, /**< context */
}
else if (has_arguments && scanner_literal_is_arguments (literal_p))
{
/* Arguments object is directly referenced from the function arguments */
new_literal_pool_p->status_flags |= SCANNER_LITERAL_POOL_ARGUMENTS_IN_ARGS;

if (type & SCANNER_LITERAL_NO_REG)
Expand Down
18 changes: 18 additions & 0 deletions tests/jerry/es.next/arguments.js
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Expand Up @@ -199,3 +199,21 @@ function f19(e = (v) => eval(v))
assert(arguments === -12.5)
}
f19(undefined, "A");

function f20 (arguments, a = eval('arguments')) {
assert(a === 3.1);
assert(arguments === 3.1);
}
f20(3.1);

function f21 (arguments, a = arguments) {
assert(a === 3.1);
assert(arguments === 3.1);
}
f21(3.1);

function f22 (arguments, [a = arguments]) {
assert(a === 3.1);
assert(arguments === 3.1);
}
f22(3.1, []);