ProvidesContext.cs

class Foo {
  [ProvidesContext] IPredefinedType _predefinedTypes = ...;
  
  void DoSomething(ITreeNode node) {
    if (Check(node)) {
      var expressionType = node.GetExpressionType();
      if (expressionType.Equals(node.GetPredefinedType().Bool) {
                             // ^^^^^^^^^^^^^^^^^^^^^^^^
                             // Use aleady provided 'IPredefinedType' value from '_predefinedTypes' field 
      }
    }
  }
}

/*
Allow on fields/properties
Allow in parameters?
Check staticness of provided field/property
Allow on methods? var foo = Foo() can provide context for inner scope
Should it work recursively? We can check for [ProvidesContext] members of [ProvidesContext] type
What about subtyping? What about multiple equal types? Introduce context types traversing subtypes until common subtype?
*/