Consequence of not to be an "assignment-like context"

[Thomas Kruse]

In the LRM, it is stated that these example should not be considered as an assignment-like context: 

- a static cast
- a default correspondence between an expression in an assignment pattern and a field or element in a data object or data value

What is the consequence of this statement?

 

Especially, what is the difference between the default correspondence (as a non-assignment-like context) and

the nondefault correspondence (as an assignment-like context)?

 

Thanks a lot

   Thomas