Const RangeInclusive<T> used within match case raises error E0308

[bvanseg]

I tried this code:

use std::ops::RangeInclusive;

const MEMORY_RANGE: RangeInclusive<u16> = 0x00FF..=0x3FFF;

fn main() {
    let address: u16 = 0x0FFF;

    match address {
        // This is valid.
        0x00FF..=0x3FFF => { /* ... */ },
        // This is not valid.
        MEMORY_RANGE => { /* ... */ }
    }
}

I expected to see this happen: MEMORY_RANGE to compile without error.

Instead, this happened: MEMORY_RANGE as a case within the match raises a compiler error error[E0308]: mismatched types.

Meta

rustc --version --verbose:

rustc 1.65.0 (897e37553 2022-11-02)
binary: rustc
commit-hash: 897e37553bba8b42751c67658967889d11ecd120
commit-date: 2022-11-02
host: x86_64-unknown-linux-gnu
release: 1.65.0
LLVM version: 15.0.0

Backtrace

error[E0308]: mismatched types
  --> src/main.rs:12:9
   |
3  | const MEMORY_RANGE: RangeInclusive<u16> = 0x00FF..=0x3FFF;
   | --------------------------------------- constant defined here
...
8  |     match address {
   |           ------- this expression has type `u16`
...
12 |         MEMORY_RANGE => { /* ... */ }
   |         ^^^^^^^^^^^^
   |         |
   |         expected `u16`, found struct `RangeInclusive`
   |         `MEMORY_RANGE` is interpreted as a constant, not a new binding
   |
   = note: expected type `u16`
            found struct `RangeInclusive<u16>`
help: you may want to move the range into the match block
   |
12 |         0x00FF..=0x3FFF => { /* ... */ }
   |         ~~~~~~~~~~~~~~~

For more information about this error, try `rustc --explain E0308`.

[Noratrieb]

This error is actually correct (but it could and should be improved to mention this). The constant being used is a "constant pattern", which has to be of the same type. The range is a "range pattern", which does what you expect.

For more info, see https://doc.rust-lang.org/reference/patterns.html