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Added comments providing justification for support of calling deref_* with wrong variant

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This commit is contained in:
Brad Gibson 2018-05-02 19:16:29 -07:00
parent c025fdebba
commit e1d5509bf3
1 changed files with 5 additions and 1 deletions
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6
src/libcore/tests/result.rs
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@ -290,7 +290,11 @@ fn test_result_deref() {
let expected_result = Result::Err::<&u32, &[i32]>(&[5, 4, 3, 2, 1][..]);
assert_eq!(ref_err.deref(), expected_result);
// *Odd corner cases (tested for completeness)*
// The following cases test calling deref_* with the wrong variant (i.e.
// `deref_ok()` with a `Result::Err()`, or `deref_err()` with a `Result::Ok()`.
// While unusual, these cases are supported to ensure that an `inner_deref`
// call can still be made even when one of the Result types does not implement
// `Deref` (for example, std::io::Error).
// &Result<T, E: Deref>::Ok(T).deref_err() ->
// Result<&T, &E::Deref::Target>::Ok(&T)