unnecessary_wraps misses 'return'

[taiki-e]

I tried this code:

fn func(s: &str) -> Option<&'static [&'static str]> {
    Some(match s {
        "a" => &["A"],
        _ => return None,
    })
}

I expected to see this happen: no warning

Instead, this happened:
unnecessary_wraps misses return None and emit warning.

warning: this function's return value is unnecessarily wrapped by `Option`
 --> src/lib.rs:1:1
  |
1 | / fn func(s: &str) -> Option<&'static [&'static str]> {
2 | |     Some(match s {
3 | |         "a" => &["A"],
4 | |         _ => return None,
5 | |     })
6 | | }
  | |_^
  |
  = note: `#[warn(clippy::unnecessary_wraps)]` on by default
  = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#unnecessary_wraps
help: remove `Option` from the return type...
  |
1 | fn func(s: &str) -> &'static [&'static str] {
  |                     ^^^^^^^^^^^^^^^^^^^^^^^
help: ...and change the returning expressions
  |
2 |     match s {
3 |         "a" => &["A"],
4 |         _ => return None,
5 |     }
  |

Meta

• cargo clippy -V: clippy 0.0.212 (1c389ff 2020-11-24)
• rustc -Vv:

  rustc 1.50.0-nightly (1c389ffef 2020-11-24)
  binary: rustc
  commit-hash: 1c389ffeff814726dec325f0f2b0c99107df2673
  commit-date: 2020-11-24
  host: x86_64-apple-darwin
  release: 1.50.0-nightly
  

Mentioning @matsujika who implemented this lint in #6070.

[giraffate]

@rustbot modify labels: +L-suggestion-causes-error

[hkmatsumoto]

@taiki-e Thanks for filing the issue, it looks like the match needs an arm for hir::ExprKind::Call.
This wasn't the case. Created PR with an alternative solution.