Open
Description
openedon Jun 7, 2024
Code
enum E {
A,
B,
C,
}
fn foo(e: E) {
let bar;
match e {
E::A => return,
E::B => {}
E::C => {
bar = 5;
}
}
let _baz = bar;
}Current output
error[E0381]: used binding `bar` is possibly-uninitialized
--> src/lib.rs:19:16
|
8 | let bar;
| --- binding declared here but left uninitialized
9 | match e {
10 | E::A => return,
| ---- if this pattern is matched, `bar` is not initialized
11 |
12 | E::B => {}
| ---- if this pattern is matched, `bar` is not initialized
...
19 | let _baz = bar;
| ^^^ `bar` used here but it is possibly-uninitialized
For more information about this error, try `rustc --explain E0381`.Desired output
error[E0381]: used binding `bar` is possibly-uninitialized
--> src/lib.rs:19:16
|
8 | let bar;
| --- binding declared here but left uninitialized
9 | match e {
10 | E::A => return,
11 |
12 | E::B => {}
| ---- if this pattern is matched, `bar` is not initialized
...
19 | let _baz = bar;
| ^^^ `bar` used here but it is possibly-uninitialized
For more information about this error, try `rustc --explain E0381`.Rationale and extra context
Yes bar is not initialized in the E::A arm, but the goal of the diagnostic should be to print the spans that the user needs to *fix*. The E::A arm diverges so the user only needs to fix the E::B arm. So the report for E::B is correct, but the one for E::A should not be emitted.
Other cases
My original code that triggered this was similar to wrapping the whole body of foo in a loop {} and using break instead of return. The rationale is the same.
Rust Version
rustc 1.80.0-nightly (a330e4959 2024-06-04)
binary: rustc
commit-hash: a330e49593ee890f9197727a3a558b6e6b37f843
commit-date: 2024-06-04
host: x86_64-unknown-linux-gnu
release: 1.80.0-nightly
LLVM version: 18.1.6Anything else?
No response
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