Differentiate Reference and mut

[joe-conigliaro]

Let's say a variable named my_var is declared using mut keyword: mut my_var = 1 the type of my_var will be int, and currently type.nr_muls will be incremented making a regular reference and a mut reference indistinguishable using the type.is_ptr() / type.nr_muls() methods. It is still possible to achieve but a little bit convoluted and confusing.

On the next use of my_var a new identifier will be created which will point to the variable declaration, it will also set ident.is_mut if the identifier was preceded by the mut for example in cases such as:

• passed as a mutable function argument
• used in a mut match: match mut my_var {
• mutable loop var: for mut x in items

The implementation I'm suggesting will make it much cleaner and simpler to differentiate between regular reference and mutable variables.