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Only start a destructuring pattern at the head of an AssignmentExpression #1652

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Only start a destructuring pattern at the head of an AssignmentExpression #1652

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7ff1901
Only start a destructuring pattern at the head of an AssignmentExpres…
claude Aug 6, 2026
30c7c45
Add a test for destructuring only at the head of an assignment
claude Aug 7, 2026
f1e14e1
Drop the private-field assignment target from the expected failures
claude Aug 7, 2026
cb47703
Cover more of the head/non-head boundary for destructuring
andreasrosdal Aug 7, 2026
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24 changes: 15 additions & 9 deletions quickjs.c
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Original file line number Diff line number Diff line change
Expand Up @@ -25365,6 +25365,9 @@ static __exception int js_parse_object_literal(JSParseState *s)
/* forbid the exponentiation operator in js_parse_unary() */
#define PF_POW_FORBIDDEN (1 << 3)
#define PF_AWAIT_USING (1 << 4)
/* an object/array literal may start a destructuring assignment: only set at
the leftmost position of an AssignmentExpression */
#define PF_PATTERN (1 << 5)

static __exception int js_parse_postfix_expr(JSParseState *s, int parse_flags);

Expand Down Expand Up @@ -27247,7 +27250,8 @@ static __exception int js_parse_postfix_expr(JSParseState *s, int parse_flags)
case '[':
{
int skip_bits;
if (js_parse_skip_parens_token(s, &skip_bits, false) == '=') {
if ((parse_flags & PF_PATTERN) &&
js_parse_skip_parens_token(s, &skip_bits, false) == '=') {
if (js_parse_destructuring_element(s, 0, false, false, skip_bits & SKIP_HAS_ELLIPSIS, true, false) < 0)
return -1;
} else {
Expand Down Expand Up @@ -27912,7 +27916,8 @@ static __exception int js_parse_unary(JSParseState *s, int parse_flags)
parse_flags = 0;
break;
default:
if (js_parse_postfix_expr(s, PF_POSTFIX_CALL))
if (js_parse_postfix_expr(s, PF_POSTFIX_CALL |
(parse_flags & PF_PATTERN)))
return -1;
if (!s->got_lf &&
(s->token.val == TOK_DEC || s->token.val == TOK_INC)) {
Expand Down Expand Up @@ -27955,7 +27960,7 @@ static __exception int js_parse_expr_binary(JSParseState *s, int level,
int op, opcode;

if (level == 0) {
return js_parse_unary(s, PF_POW_ALLOWED);
return js_parse_unary(s, PF_POW_ALLOWED | (parse_flags & PF_PATTERN));
} else if (s->token.val == TOK_PRIVATE_NAME &&
(parse_flags & PF_IN_ACCEPTED) && level == 4 &&
peek_token(s, false) == TOK_IN) {
Expand All @@ -27967,7 +27972,7 @@ static __exception int js_parse_expr_binary(JSParseState *s, int level,
goto fail_private_in;
if (next_token(s))
goto fail_private_in;
if (js_parse_expr_binary(s, level - 1, parse_flags)) {
if (js_parse_expr_binary(s, level - 1, parse_flags & ~PF_PATTERN)) {
fail_private_in:
JS_FreeAtom(s->ctx, atom);
return -1;
Expand Down Expand Up @@ -28105,7 +28110,7 @@ static __exception int js_parse_expr_binary(JSParseState *s, int level,
if (next_token(s))
return -1;
emit_source_loc(s);
if (js_parse_expr_binary(s, level - 1, parse_flags))
if (js_parse_expr_binary(s, level - 1, parse_flags & ~PF_PATTERN))
return -1;
emit_op(s, opcode);
}
Expand Down Expand Up @@ -28136,10 +28141,11 @@ static __exception int js_parse_logical_and_or(JSParseState *s, int op,
emit_op(s, OP_drop);

if (op == TOK_LAND) {
if (js_parse_expr_binary(s, 8, parse_flags))
if (js_parse_expr_binary(s, 8, parse_flags & ~PF_PATTERN))
return -1;
} else {
if (js_parse_logical_and_or(s, TOK_LAND, parse_flags))
if (js_parse_logical_and_or(s, TOK_LAND,
parse_flags & ~PF_PATTERN))
return -1;
}
if (s->token.val != op) {
Expand Down Expand Up @@ -28171,7 +28177,7 @@ static __exception int js_parse_coalesce_expr(JSParseState *s, int parse_flags)
emit_goto(s, OP_if_false, label1);
emit_op(s, OP_drop);

if (js_parse_expr_binary(s, 8, parse_flags))
if (js_parse_expr_binary(s, 8, parse_flags & ~PF_PATTERN))
return -1;
if (s->token.val != TOK_DOUBLE_QUESTION_MARK)
break;
Expand Down Expand Up @@ -28401,7 +28407,7 @@ static __exception int js_parse_assign_expr2(JSParseState *s, int parse_flags)
/* name0 is used to check for OP_set_name pattern, not duplicated */
name0 = s->token.u.ident.atom;
}
if (js_parse_cond_expr(s, parse_flags))
if (js_parse_cond_expr(s, parse_flags | PF_PATTERN))
return -1;

op = s->token.val;
Expand Down
2 changes: 0 additions & 2 deletions test262_errors.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -27,8 +27,6 @@ test262/test/language/expressions/assignment/target-member-computed-reference.js
test262/test/language/expressions/assignment/target-member-computed-reference.js:22: strict mode: Test262Error: Expected a DummyError but got a Test262Error
test262/test/language/expressions/assignment/target-super-computed-reference.js:20: Test262Error: Expected a DummyError but got a Test262Error
test262/test/language/expressions/assignment/target-super-computed-reference.js:20: strict mode: Test262Error: Expected a DummyError but got a Test262Error
test262/test/language/expressions/in/private-field-invalid-assignment-target.js:23: unexpected error type: Test262: This statement should not be evaluated.
test262/test/language/expressions/in/private-field-invalid-assignment-target.js:23: strict mode: unexpected error type: Test262: This statement should not be evaluated.
test262/test/language/expressions/object/computed-property-name-topropertykey-before-value-evaluation.js:31: Test262Error: Expected SameValue(«"bad"», «"ok"») to be true
test262/test/language/expressions/object/computed-property-name-topropertykey-before-value-evaluation.js:31: strict mode: Test262Error: Expected SameValue(«"bad"», «"ok"») to be true
test262/test/language/module-code/ambiguous-export-bindings/import-and-export-propagates-binding.js:75: SyntaxError: export 'foo' in module 'test262/test/language/module-code/ambiguous-export-bindings/imp' is ambiguous
Expand Down
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