Description
openedon Oct 1, 2020
We should rename LayoutErr to LayoutError in core::alloc. See prior discussion here: #57 (comment)
Since LayoutErr is stable, we can provide a type alias
pub type LayoutErr = LayoutErrorI've implemented this change here, rust-lang/rust@master...exrook:rename-layouterr. Some things that are still unclear to me are:
- Should
LayoutErrbe deprecated - Should
LayoutErrorbe behind a feature flag at first
If LayoutErr is deprecated or marked for deprecation in a later version, it can no longer be used in std because of #[deny(deprecated,deprecated_in_future)] being in effect. I don't think it makes sense to have LayoutError replace LayoutErr in std, but then be behind a feature flag, only usable on nightly. This is mainly a usability issue because crates can of course continue to use LayoutErr despite the stdlib rustdocs showing LayoutError.
Option 1
Is it possible to make LayoutError immediately stable, then deprecate LayoutErr in the same or a later release? The following would then be possible:
#[stable(feature = "alloc_layout", since = "1.28.0")]
#[rustc_deprecated(since = "1.48.0", reason = "use LayoutError instead", suggestion = "LayoutError")]
pub type LayoutErr = LayoutError;
#[stable(feature = "alloc_layout_error", since = "1.48.0")]
#[derive(Clone, PartialEq, Eq, Debug)]
pub struct LayoutError {
private: (),
}Option 2
I think this would make more sense than trying to do a staged approach of adding LayoutError as unstable, then marking it stable, then deprecating the LayoutErr type alias.
Stage 1 - release 1.N
#[stable(feature = "alloc_layout", since = "1.28.0")]
pub type LayoutErr = LayoutError;
#[unstable(feature = "alloc_layout_error", issue = "32838")]
#[derive(Clone, PartialEq, Eq, Debug)]
pub struct LayoutError {
private: (),
}Stage 2 - release 1.N+1
#[stable(feature = "alloc_layout", since = "1.28.0")]
pub type LayoutErr = LayoutError;
#[stable(feature = "alloc_layout_error", since = "1.49.0")]
#[derive(Clone, PartialEq, Eq, Debug)]
pub struct LayoutError {
private: (),
}Stage 3 - release 1.N+2
#[stable(feature = "alloc_layout", since = "1.28.0")]
#[rustc_deprecated(since = "1.51.0", reason = "use LayoutError instead", suggestion = "LayoutError")]
pub type LayoutErr = LayoutError;
#[stable(feature = "alloc_layout_error", since = "1.49.0")]
#[derive(Clone, PartialEq, Eq, Debug)]
pub struct LayoutError {
private: (),
}