delete on an optional chain returns true without deleting the property #5319

Applying delete to a non-short-circuited optional chain (such as delete o?.a) evaluates the property access and returns true, but leaves the property on the object.

JerryScript revision

v3.0.0 and master (b7069350)

Build platform

macOS 26.3 (Darwin 25.3.0 arm64)

Build steps

tools/build.py --profile=es.next

Test case

var o = { a: 1 };
print(delete o?.a, "a" in o);

var p = { b: { c: 2 } };
print(delete p?.b.c, "c" in p.b);

var q = { a: 1 };
print(delete q?.["a"], "a" in q);

Output

true true
true true
true true

Expected behavior

It should print true false on all three lines, as V8 and SpiderMonkey do and as ECMA-262 requires (delete on a non-short-circuited OptionalExpression receives a property Reference and must invoke [[Delete]] on the base object).

Credit: https://ucsbplse.github.io/