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Rollup merge of #76614 - NoraCodes:nora/control_flow_enum, r=scottmcm 

change the order of type arguments on ControlFlow

This allows ControlFlow<BreakType> which is much more ergonomic for common iterator combinator use cases.

Addresses one component of #75744
This commit is contained in:
Jonas Schievink 2020-10-24 22:39:41 +02:00 committed by GitHub
parent 01a38f0d9a bc2317915f
commit a547055184
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GPG Key ID: 4AEE18F83AFDEB23
6 changed files with 20 additions and 28 deletions
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5
compiler/rustc_data_structures/src/graph/iterate/mod.rs
View File

@ -1,6 +1,7 @@
use super::{DirectedGraph, WithNumNodes, WithStartNode, WithSuccessors};
use rustc_index::bit_set::BitSet;
use rustc_index::vec::IndexVec;
use std::ops::ControlFlow;
#[cfg(test)]
mod tests;
@ -86,10 +87,6 @@ where
}
}
/// Allows searches to terminate early with a value.
// FIXME (#75744): remove the alias once the generics are in a better order and `C=()`.
pub type ControlFlow<T> = std::ops::ControlFlow<(), T>;
/// The status of a node in the depth-first search.
///
/// See the documentation of `TriColorDepthFirstSearch` to see how a node's status is updated

3
compiler/rustc_mir_build/src/lints.rs
View File

@ -1,5 +1,5 @@
use rustc_data_structures::graph::iterate::{
ControlFlow, NodeStatus, TriColorDepthFirstSearch, TriColorVisitor,
NodeStatus, TriColorDepthFirstSearch, TriColorVisitor,
};
use rustc_hir::intravisit::FnKind;
use rustc_middle::hir::map::blocks::FnLikeNode;
@ -8,6 +8,7 @@ use rustc_middle::ty::subst::{GenericArg, InternalSubsts};
use rustc_middle::ty::{self, AssocItem, AssocItemContainer, Instance, TyCtxt};
use rustc_session::lint::builtin::UNCONDITIONAL_RECURSION;
use rustc_span::Span;
use std::ops::ControlFlow;
crate fn check<'tcx>(tcx: TyCtxt<'tcx>, body: &Body<'tcx>) {
let def_id = body.source.def_id().expect_local();

10
library/core/src/iter/adapters/mod.rs
View File

@ -1280,7 +1280,7 @@ where
#[inline]
fn find<T, B>(
f: &mut impl FnMut(T) -> Option<B>,
) -> impl FnMut((), T) -> ControlFlow<(), B> + '_ {
) -> impl FnMut((), T) -> ControlFlow<B> + '_ {
move |(), x| match f(x) {
Some(x) => ControlFlow::Break(x),
None => ControlFlow::CONTINUE,
@ -2059,7 +2059,7 @@ where
flag: &'a mut bool,
p: &'a mut impl FnMut(&T) -> bool,
mut fold: impl FnMut(Acc, T) -> R + 'a,
) -> impl FnMut(Acc, T) -> ControlFlow<Acc, R> + 'a {
) -> impl FnMut(Acc, T) -> ControlFlow<R, Acc> + 'a {
move |acc, x| {
if p(&x) {
ControlFlow::from_try(fold(acc, x))
@ -2372,7 +2372,7 @@ where
fn check<T, Acc, R: Try<Ok = Acc>>(
mut n: usize,
mut fold: impl FnMut(Acc, T) -> R,
) -> impl FnMut(Acc, T) -> ControlFlow<Acc, R> {
) -> impl FnMut(Acc, T) -> ControlFlow<R, Acc> {
move |acc, x| {
n -= 1;
let r = fold(acc, x);
@ -2496,7 +2496,7 @@ where
fn check<'a, T, Acc, R: Try<Ok = Acc>>(
n: &'a mut usize,
mut fold: impl FnMut(Acc, T) -> R + 'a,
) -> impl FnMut(Acc, T) -> ControlFlow<Acc, R> + 'a {
) -> impl FnMut(Acc, T) -> ControlFlow<R, Acc> + 'a {
move |acc, x| {
*n -= 1;
let r = fold(acc, x);
@ -2681,7 +2681,7 @@ where
state: &'a mut St,
f: &'a mut impl FnMut(&mut St, T) -> Option<B>,
mut fold: impl FnMut(Acc, B) -> R + 'a,
) -> impl FnMut(Acc, T) -> ControlFlow<Acc, R> + 'a {
) -> impl FnMut(Acc, T) -> ControlFlow<R, Acc> + 'a {
move |acc, x| match f(state, x) {
None => ControlFlow::Break(try { acc }),
Some(x) => ControlFlow::from_try(fold(acc, x)),

4
library/core/src/iter/traits/double_ended.rs
View File

@ -339,9 +339,7 @@ pub trait DoubleEndedIterator: Iterator {
P: FnMut(&Self::Item) -> bool,
{
#[inline]
fn check<T>(
mut predicate: impl FnMut(&T) -> bool,
) -> impl FnMut((), T) -> ControlFlow<(), T> {
fn check<T>(mut predicate: impl FnMut(&T) -> bool) -> impl FnMut((), T) -> ControlFlow<T> {
move |(), x| {
if predicate(&x) { ControlFlow::Break(x) } else { ControlFlow::CONTINUE }
}

14
library/core/src/iter/traits/iterator.rs
View File

@ -2109,7 +2109,7 @@ pub trait Iterator {
F: FnMut(Self::Item) -> bool,
{
#[inline]
fn check<T>(mut f: impl FnMut(T) -> bool) -> impl FnMut((), T) -> ControlFlow<(), ()> {
fn check<T>(mut f: impl FnMut(T) -> bool) -> impl FnMut((), T) -> ControlFlow<()> {
move |(), x| {
if f(x) { ControlFlow::CONTINUE } else { ControlFlow::BREAK }
}
@ -2162,7 +2162,7 @@ pub trait Iterator {
F: FnMut(Self::Item) -> bool,
{
#[inline]
fn check<T>(mut f: impl FnMut(T) -> bool) -> impl FnMut((), T) -> ControlFlow<(), ()> {
fn check<T>(mut f: impl FnMut(T) -> bool) -> impl FnMut((), T) -> ControlFlow<()> {
move |(), x| {
if f(x) { ControlFlow::BREAK } else { ControlFlow::CONTINUE }
}
@ -2222,9 +2222,7 @@ pub trait Iterator {
P: FnMut(&Self::Item) -> bool,
{
#[inline]
fn check<T>(
mut predicate: impl FnMut(&T) -> bool,
) -> impl FnMut((), T) -> ControlFlow<(), T> {
fn check<T>(mut predicate: impl FnMut(&T) -> bool) -> impl FnMut((), T) -> ControlFlow<T> {
move |(), x| {
if predicate(&x) { ControlFlow::Break(x) } else { ControlFlow::CONTINUE }
}
@ -2255,9 +2253,7 @@ pub trait Iterator {
F: FnMut(Self::Item) -> Option<B>,
{
#[inline]
fn check<T, B>(
mut f: impl FnMut(T) -> Option<B>,
) -> impl FnMut((), T) -> ControlFlow<(), B> {
fn check<T, B>(mut f: impl FnMut(T) -> Option<B>) -> impl FnMut((), T) -> ControlFlow<B> {
move |(), x| match f(x) {
Some(x) => ControlFlow::Break(x),
None => ControlFlow::CONTINUE,
@ -2296,7 +2292,7 @@ pub trait Iterator {
R: Try<Ok = bool>,
{
#[inline]
fn check<F, T, R>(mut f: F) -> impl FnMut((), T) -> ControlFlow<(), Result<T, R::Error>>
fn check<F, T, R>(mut f: F) -> impl FnMut((), T) -> ControlFlow<Result<T, R::Error>>
where
F: FnMut(&T) -> R,
R: Try<Ok = bool>,

12
library/core/src/ops/control_flow.rs
View File

@ -3,7 +3,7 @@ use crate::ops::Try;
/// Used to make try_fold closures more like normal loops
#[unstable(feature = "control_flow_enum", reason = "new API", issue = "75744")]
#[derive(Debug, Clone, Copy, PartialEq)]
pub enum ControlFlow<C, B> {
pub enum ControlFlow<B, C = ()> {
/// Continue in the loop, using the given value for the next iteration
Continue(C),
/// Exit the loop, yielding the given value
@ -11,7 +11,7 @@ pub enum ControlFlow<C, B> {
}
#[unstable(feature = "control_flow_enum", reason = "new API", issue = "75744")]
impl<C, B> Try for ControlFlow<C, B> {
impl<B, C> Try for ControlFlow<B, C> {
type Ok = C;
type Error = B;
#[inline]
@ -31,7 +31,7 @@ impl<C, B> Try for ControlFlow<C, B> {
}
}
impl<C, B> ControlFlow<C, B> {
impl<B, C> ControlFlow<B, C> {
/// Returns `true` if this is a `Break` variant.
#[inline]
#[unstable(feature = "control_flow_enum", reason = "new API", issue = "75744")]
@ -58,7 +58,7 @@ impl<C, B> ControlFlow<C, B> {
}
}
impl<R: Try> ControlFlow<R::Ok, R> {
impl<R: Try> ControlFlow<R, R::Ok> {
/// Create a `ControlFlow` from any type implementing `Try`.
#[unstable(feature = "control_flow_enum", reason = "new API", issue = "75744")]
#[inline]
@ -80,7 +80,7 @@ impl<R: Try> ControlFlow<R::Ok, R> {
}
}
impl<B> ControlFlow<(), B> {
impl<B> ControlFlow<B, ()> {
/// It's frequently the case that there's no value needed with `Continue`,
/// so this provides a way to avoid typing `(())`, if you prefer it.
///
@ -102,7 +102,7 @@ impl<B> ControlFlow<(), B> {
pub const CONTINUE: Self = ControlFlow::Continue(());
}
impl<C> ControlFlow<C, ()> {
impl<C> ControlFlow<(), C> {
/// APIs like `try_for_each` don't need values with `Break`,
/// so this provides a way to avoid typing `(())`, if you prefer it.
///