Clippy 1.63 fails to detect vec-init-then-push

[junglie85]

Summary

Clippy 1.63 fails to detect vec-init-then-push but it is detected with 1.62. This seems to only happen when there is an if statement after the initial push that conditionally pushes a subsequent element to the vec.

Lint Name

vec-init-then-push

Reproducer

I tried this code:

fn main() {
    let vec = vec_init_then_push(false);
    dbg!(vec);
}

fn vec_init_then_push(some_condition: bool) -> Vec<usize> {
    let mut vec = Vec::new();
    vec.push(1);

    if some_condition {
        vec.push(2);
    }

    vec
}

I expected to see this happen:

cargo clippy -- -D warnings
    Checking bad-clippy v0.1.0 (/Users/junglie85/bad-clippy)
error: calls to `push` immediately after creation
 --> src/main.rs:7:5
  |
7 | /     let mut vec = Vec::new();
8 | |     vec.push(1);
  | |________________^ help: consider using the `vec![]` macro: `let mut vec = vec![..];`
  |
  = note: `-D clippy::vec-init-then-push` implied by `-D warnings`
  = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#vec_init_then_push

error: could not compile `bad-clippy` due to previous error

Instead, this happened:

cargo clippy -- -D warnings
    Finished dev [unoptimized + debuginfo] target(s) in 0.14s

Version

False negative:

rustc 1.63.0 (4b91a6ea7 2022-08-08)
binary: rustc
commit-hash: 4b91a6ea7258a947e59c6522cd5898e7c0a6a88f
commit-date: 2022-08-08
host: aarch64-apple-darwin
release: 1.63.0
LLVM version: 14.0.5

Detects:

rustc 1.62.1 (e092d0b6b 2022-07-16)
binary: rustc
commit-hash: e092d0b6b43f2de967af0887873151bb1c0b18d3
commit-date: 2022-07-16
host: aarch64-apple-darwin
release: 1.62.1
LLVM version: 14.0.5

[junglie85]

I swear #7071 didn't come up when I first searched. But it makes sense and I see the fix was merged a couple of months ago. The new behaviour is preferable and my false positive bug is only really a bug if the behavious is supposed to be unchanged. I'll close.