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Implementation of abstract properties doesn't care about readonly and/or writeonly properties #62527
Closed as not planned
Description
🔎 Search Terms
abstract readonly implementation
🕗 Version & Regression Information
Tried in the playground on Nightly (v6.0.0-dev.20251002) and on v3.3.3333, there's no difference
⏯ Playground Link
💻 Code
{
abstract class A {
abstract a: number; // Not readonly
}
// TypeScript doesn't care that this doesn't implement the setter
class B extends A {
get a() { return 1; } // Readonly
}
const l: A = new B();
l.a = 8; // No error (Reasonable)
}
{
abstract class A {
abstract readonly a: number; // Readonly
}
// TypeScript doesn't care that this doesn't implement the getter
class B extends A {
set a(v: number) { } // Writeonly
}
const l = new B();
l.a = 8; // No error (Good)
}🙁 Actual behavior
TypeScript only cares about the name of the implemented property and its type
🙂 Expected behavior
It should also care about whether it's readable and/or writable
Additional information about the issue
No response
Activity
MartinJohns commentedon Oct 2, 2025
Duplicate of #49345.
AFatNiBBa commentedon Oct 2, 2025
Just as a confirmation, is it true that:
MartinJohns commentedon Oct 2, 2025
There is no flag. But there's an open PR about introducing such a flag: #58296
typescript-bot commentedon Oct 5, 2025
This issue has been marked as "Duplicate" and has seen no recent activity. It has been automatically closed for house-keeping purposes.