🚀 feature request

Relevant Package

This feature request is for @angular/core

Description

There is a long history of discussion about whether / how to have the compiler enforce that specific inputs are provided to components: #11904 #18156 #24879 #28403 #30974

However, all of those are now closed and locked. They contain some advice about how to mitigate the problem, or kick the can down the road ("One day I hope we'll be able to do this. That day is not today."), but thanks to the lock-bot none of them can be used to continue the conversation, so I guess we need yet another issue, because I believe the problem still exists.

Describe the solution you'd like

It should be possible to annotate inputs such that using a component in a template without providing a value for that input is a compile-time error. Template checking has come a long way, and it's already possible for the compiler to flag providing the wrong type as an argument. Combine with the strictPropertyInitializers flag, and such a check could rely on the existing ! assertion operator.

Describe alternatives you've considered

The best approach I've seen while reviewing the above issues is specifying the required attributes in the selector component metadata, but a) apparently that won't catch passing null or undefined to an Input that not defined with a type that includes those values, and b) that appears to break certain test harnesses? Also, I haven't started using strictTemplates / fullTemplateTypeCheck yet due to some problems in previous versions with narrowing on *ngIf that may or may not have been resolved -- those existing capabilities may address some or all of this need.