`redundant_guards` on match guard of an expression rebinding

Summary

When matching an expression with a guard that is true only if the expression's rebinding does not have a certain value, clippy will warn the guard as redundant_guards and its help message will change the code's original meaning.

Reproducer

I tried this code:

fn main() {
    match 1 + 1 {
        b if match b {
            1 => false,
            _ => true
        } => println!("branch 1"),
        _ => println!("branch 2")
    }
}

I expected to see this happen:

No warning of redundant guard

Instead, this happened:

warning: redundant guard
 --> src/main.rs:3:14
  |
3 |           b if match b {
  |  ______________^
4 | |             1 => false,
5 | |             _ => true
6 | |         } => println!("branch 1"),
  | |_________^
  |
  = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#redundant_guards
  = note: `#[warn(clippy::redundant_guards)]` on by default
help: try
  |
3 -         b if match b {
3 +         1 => println!("branch 1"),
  |

Version

rustc 1.76.0-nightly (283170175 2023-11-17)
binary: rustc
commit-hash: 2831701757eb7b3105eda26a306c2f3a97e2664b
commit-date: 2023-11-17
host: x86_64-unknown-linux-gnu
release: 1.76.0-nightly
LLVM version: 17.0.5

Additional Labels

No response

Start by reproducing the Rust snippet and inspect the implementation and existing tests for Clippy's redundant_guards lint. Verify that the lint does not warn on this expression-rebinding guard and that any suggested replacement preserves the program's original behavior.