Kotlin: why the compiler needs the `const` modifier?

Question

In Kotlin there are:

• val - readonly property
• const val - compile-time constants

From the documentation:

Compile-Time Constants

Properties the value of which is known at compile time can be marked as compile time constants using the const modifier. Such properties need to fulfill the following requirements:

• Top-level or member of an object
• Initialized with a value of type String or a primitive type
• No custom getter

Given that kotlin compiler does know to identify initialized values (such as there is no need defining the variable type in an initializer):

• Why does the compiler needs the programmer's assistance?
• Can't it identify "properties the value of which is known at compile time" and "add" the const modifier by itself?

Answer 1

The const modifier seriously changes the contract of a property.

For example, if you have a regular property, you may add a special getter to it without affecting the code which uses it.

On the other hand, you would have to recompile the user code in order to remove const and add getters. In other words, you loose the advantage of having a property over a field.