manual_unwrap_or_default should not trigger in constant context (false positive)

[tspiteri]

Summary

Since unwrap_or_default is not a const method, it should not be suggested in constant context. As it is, the lint gives a suggestion that would fail to compile.

Lint Name

manual_unwrap_or_default

Reproducer

I tried this code:

pub const fn foo(a: Option<bool>) -> bool {
    match a {
        Some(s) => s,
        None => false,
    }
}

I saw this happen:

    Checking playground v0.1.0 (/tmp/playground)
warning: match can be simplified with `.unwrap_or_default()`
 --> src/lib.rs:2:5
  |
2 | /     match a {
3 | |         Some(s) => s,
4 | |         None => false,
5 | |     }
  | |_____^ help: replace it with: `a.unwrap_or_default()`
  |
  = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#manual_unwrap_or_default
  = note: `#[warn(clippy::manual_unwrap_or_default)]` on by default

warning: `playground` (lib) generated 1 warning (run `cargo clippy --fix --lib -p playground` to apply 1 suggestion)
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.03s

I expected to see this happen:

No warning.

Version

rustc 1.79.0-nightly (5f2c7d2bf 2024-03-25)
binary: rustc
commit-hash: 5f2c7d2bfd46cad00352ab7cd66242077e2e518c
commit-date: 2024-03-25
host: x86_64-unknown-linux-gnu
release: 1.79.0-nightly
LLVM version: 18.1.2

Additional Labels

@rustbot label +I-suggestion-causes-error

[J-ZhengLi]

@rustbot claim