I'm curious about how to simplify the constraint (...

# compiler

[Icyrockton]

I'm curious about how to simplify the constraint (e.g. simplifyLowerConstraint, simplifyUpperConstraint).
if we have Foo <: T? , how can we introduce Foo & Any <: T ?
I have read kotlin specification Definitely Non-nullable Types part , it mention T & Any is non-nullable type , but it's only used for type parameter.
against Foo & Any is just a intersection type or it's an definitely non-nullable type?

[dmitriy.novozhilov]

DNN(T) and T & Any are the identical types
There is a special abstraction for definitely non null types only for historical and performance reasons

[Icyrockton]

can you step by step explain how Foo <: T? can introduce Foo & Any <: T ? thank you

[dmitriy.novozhilov]

• Foo <: T?
• Foo <: T & Nothing? expand T?
• Foo & Any <: T remove null from values of types in both sides