Allow declarations with names that collide with primitive types when using @"" syntax

[Vexu]

Originally from here: #6060 (comment)
Alternative to #1802

const _ = 2; // error: `_` is not a declarable symbol
const @"_" = 2; // ok

const bool = 2; // error: variable shadows primitive type 'bool'
const @"bool" = 2; // ok

[tadeokondrak]

Would this work?

const @"bool" = 2;
const other: bool = false;

If not, shadowing a predefined type or identifier would make it impossible to use, since you couldn't even do

const my_bool = bool;
const @"bool" = 2;
const other: my_bool = false;

since top level decls are order-independent.

[Vexu]

It would make sense for them to be distinct since bool is a constant and allowing it to be modified by an alias would result in some really strange behavior.

[tadeokondrak]

It would make sense for them to be distinct

Wouldn't the only way to implement that be the same as #1802?

[Vexu]

No. This works because the identifiers using the @"" syntax are actually strings that need to be resolved first. The main difference between the two approaches is that this doesn't make them into keywords. This will be most noticeable in container fields where using bool will remain valid while the other proposal would require using @"bool".

[andrewrk]

cc @ehaas - I believe some things you were doing were blocking on this.