b873fa6d42
Stabilize some Result methods as const Stabilize the following methods of Result as const: - `is_ok` - `is_err` - `as_ref` A test is also included, analogous to the test for `const_option`. These methods are currently const under the unstable feature `const_result` (tracking issue: #67520). I believe these methods to be eligible for stabilization because of the stabilization of #49146 (Allow if and match in constants) and the trivial implementations, see also: [PR#75463](https://github.com/rust-lang/rust/pull/75463) and [PR#76135](https://github.com/rust-lang/rust/pull/76135). Note: these methods are the only methods currently under the `const_result` feature, thus this PR results in the removal of the feature. Related: #76225