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5936ecc24f
Stabilize `ops::ControlFlow` (just the type) Tracking issue: https://github.com/rust-lang/rust/issues/75744 (which also tracks items *not* closed by this PR). With the new `?` desugar implemented, [it's no longer possible to mix `Result` and `ControlFlow`](https://play.rust-lang.org/?version=nightly&mode=debug&edition=2018&gist=13feec97f5c96a9d791d97f7de2d49a6). (At the time of making this PR, godbolt was still on the 2021-05-01 nightly, where you can see that [the mixing example compiled](https://rust.godbolt.org/z/13Ke54j16).) That resolves the only blocker I know of, so I'd like to propose that `ControlFlow` be considered for stabilization. Its basic existence was part of https://github.com/rust-lang/rfcs/pull/3058, where it got a bunch of positive comments (examples [1](https://github.com/rust-lang/rfcs/pull/3058#issuecomment-758277325) [2](https://github.com/rust-lang/rfcs/pull/3058#pullrequestreview-592106494) [3](https://github.com/rust-lang/rfcs/pull/3058#issuecomment-784444155) [4](https://github.com/rust-lang/rfcs/pull/3058#issuecomment-797031584)). Its use in the compiler has been well received (https://github.com/rust-lang/rust/pull/78182#issuecomment-713695594), and there are ecosystem updates interested in using it (https://github.com/rust-itertools/itertools/issues/469#issuecomment-677729589, https://github.com/jonhoo/rust-imap/issues/194). As this will need an FCP, picking a libs member manually: r? `@m-ou-se` ## Stabilized APIs ```rust #[derive(Debug, Clone, Copy, PartialEq)] pub enum ControlFlow<B, C = ()> { /// Exit the operation without running subsequent phases. Break(B), /// Move on to the next phase of the operation as normal. Continue(C), } ``` As well as using `?` on a `ControlFlow<B, _>` in a function returning `ControlFlow<B, _>`. (Note, in particular, that there's no `From::from`-conversion on the `Break` value, the way there is for `Err`s.) ## Existing APIs *not* stabilized here All the associated methods and constants: `break_value`, `is_continue`, `map_break`, [`CONTINUE`](https://doc.rust-lang.org/nightly/std/ops/enum.ControlFlow.html#associatedconstant.CONTINUE), etc. Some of the existing methods in nightly seem reasonable, some seem like they should be removed, and some need more discussion to decide. But none of them are *essential*, so [as in the RFC](https://rust-lang.github.io/rfcs/3058-try-trait-v2.html#methods-on-controlflow), they're all omitted from this PR. They can be considered separately later, as further usage demonstrates which are important.
109 lines
2.4 KiB
Rust
109 lines
2.4 KiB
Rust
#![feature(alloc_layout_extra)]
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#![feature(array_chunks)]
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#![feature(array_methods)]
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#![feature(array_map)]
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#![feature(array_windows)]
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#![feature(bool_to_option)]
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#![feature(bound_cloned)]
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#![feature(box_syntax)]
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#![feature(cell_update)]
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#![feature(cfg_panic)]
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#![feature(cfg_target_has_atomic)]
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#![feature(const_assume)]
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#![feature(const_cell_into_inner)]
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#![feature(const_maybe_uninit_assume_init)]
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#![feature(const_ptr_read)]
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#![feature(const_ptr_write)]
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#![feature(const_ptr_offset)]
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#![feature(core_intrinsics)]
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#![feature(core_private_bignum)]
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#![feature(core_private_diy_float)]
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#![feature(dec2flt)]
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#![feature(div_duration)]
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#![feature(duration_consts_2)]
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#![feature(duration_constants)]
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#![feature(exact_size_is_empty)]
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#![feature(extern_types)]
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#![feature(flt2dec)]
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#![feature(fmt_internals)]
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#![feature(hashmap_internals)]
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#![feature(try_find)]
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#![feature(is_sorted)]
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#![feature(pattern)]
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#![feature(raw)]
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#![feature(sort_internals)]
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#![feature(slice_partition_at_index)]
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#![feature(maybe_uninit_uninit_array)]
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#![feature(maybe_uninit_array_assume_init)]
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#![feature(maybe_uninit_extra)]
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#![feature(maybe_uninit_write_slice)]
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#![feature(min_specialization)]
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#![feature(step_trait)]
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#![feature(str_internals)]
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#![feature(test)]
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#![feature(trusted_len)]
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#![feature(try_trait_v2)]
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#![feature(slice_internals)]
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#![feature(slice_partition_dedup)]
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#![feature(int_error_matching)]
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#![feature(iter_advance_by)]
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#![feature(iter_partition_in_place)]
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#![feature(iter_intersperse)]
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#![feature(iter_is_partitioned)]
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#![feature(iter_order_by)]
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#![feature(iter_map_while)]
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#![feature(const_mut_refs)]
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#![feature(const_pin)]
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#![feature(const_slice_from_raw_parts)]
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#![feature(const_raw_ptr_deref)]
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#![feature(never_type)]
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#![feature(unwrap_infallible)]
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#![feature(option_result_unwrap_unchecked)]
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#![feature(result_into_ok_or_err)]
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#![feature(ptr_metadata)]
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#![feature(once_cell)]
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#![feature(unsized_tuple_coercion)]
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#![feature(const_option)]
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#![feature(integer_atomics)]
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#![feature(slice_group_by)]
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#![feature(trusted_random_access)]
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#![feature(unsize)]
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#![deny(unsafe_op_in_unsafe_fn)]
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extern crate test;
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mod alloc;
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mod any;
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mod array;
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mod ascii;
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mod atomic;
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mod bool;
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mod cell;
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mod char;
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mod clone;
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mod cmp;
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mod const_ptr;
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mod fmt;
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mod hash;
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mod intrinsics;
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mod iter;
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mod lazy;
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mod macros;
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mod manually_drop;
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mod mem;
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mod nonzero;
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mod num;
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mod ops;
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mod option;
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mod pattern;
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mod pin;
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mod ptr;
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mod result;
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mod slice;
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mod str;
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mod str_lossy;
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mod task;
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mod time;
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mod tuple;
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mod unicode;
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