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Stabilize const BTree{Map,Set}::new #102197

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merged 2 commits into from
Sep 26, 2022
Merged

Stabilize const BTree{Map,Set}::new #102197

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aa35ab8
Stabilize const `BTree{Map,Set}::new`
Noratrieb Sep 23, 2022
66484c0
Fix clippy's const fn stability check for CURRENT_RUSTC_VERSION
Noratrieb Sep 23, 2022
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2 changes: 1 addition & 1 deletion compiler/rustc_hir/src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -4,7 +4,7 @@

#![feature(associated_type_defaults)]
#![feature(closure_track_caller)]
#![feature(const_btree_new)]
#![feature(const_btree_len)]
#![cfg_attr(bootstrap, feature(let_else))]
#![feature(once_cell)]
#![feature(min_specialization)]
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6 changes: 3 additions & 3 deletions library/alloc/src/collections/btree/map.rs
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Expand Up @@ -580,7 +580,7 @@ impl<K, V> BTreeMap<K, V> {
/// map.insert(1, "a");
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_const_unstable(feature = "const_btree_new", issue = "71835")]
#[rustc_const_stable(feature = "const_btree_new", since = "CURRENT_RUSTC_VERSION")]
#[must_use]
pub const fn new() -> BTreeMap<K, V> {
BTreeMap { root: None, length: 0, alloc: ManuallyDrop::new(Global), _marker: PhantomData }
Expand Down Expand Up @@ -2392,7 +2392,7 @@ impl<K, V, A: Allocator + Clone> BTreeMap<K, V, A> {
/// ```
#[must_use]
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_const_unstable(feature = "const_btree_new", issue = "71835")]
#[rustc_const_unstable(feature = "const_btree_len", issue = "71835")]
pub const fn len(&self) -> usize {
self.length
}
Expand All @@ -2413,7 +2413,7 @@ impl<K, V, A: Allocator + Clone> BTreeMap<K, V, A> {
/// ```
#[must_use]
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_const_unstable(feature = "const_btree_new", issue = "71835")]
#[rustc_const_unstable(feature = "const_btree_len", issue = "71835")]
pub const fn is_empty(&self) -> bool {
self.len() == 0
}
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6 changes: 3 additions & 3 deletions library/alloc/src/collections/btree/set.rs
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Expand Up @@ -343,7 +343,7 @@ impl<T> BTreeSet<T> {
/// let mut set: BTreeSet<i32> = BTreeSet::new();
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_const_unstable(feature = "const_btree_new", issue = "71835")]
#[rustc_const_stable(feature = "const_btree_new", since = "CURRENT_RUSTC_VERSION")]
#[must_use]
pub const fn new() -> BTreeSet<T> {
BTreeSet { map: BTreeMap::new() }
Expand Down Expand Up @@ -1174,7 +1174,7 @@ impl<T, A: Allocator + Clone> BTreeSet<T, A> {
/// ```
#[must_use]
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_const_unstable(feature = "const_btree_new", issue = "71835")]
#[rustc_const_unstable(feature = "const_btree_len", issue = "71835")]
pub const fn len(&self) -> usize {
self.map.len()
}
Expand All @@ -1193,7 +1193,7 @@ impl<T, A: Allocator + Clone> BTreeSet<T, A> {
/// ```
#[must_use]
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_const_unstable(feature = "const_btree_new", issue = "71835")]
#[rustc_const_unstable(feature = "const_btree_len", issue = "71835")]
pub const fn is_empty(&self) -> bool {
self.len() == 0
}
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2 changes: 1 addition & 1 deletion library/alloc/src/lib.rs
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Expand Up @@ -99,7 +99,7 @@
#![feature(coerce_unsized)]
#![cfg_attr(not(no_global_oom_handling), feature(const_alloc_error))]
#![feature(const_box)]
#![cfg_attr(not(no_global_oom_handling), feature(const_btree_new))]
#![cfg_attr(not(no_global_oom_handling), feature(const_btree_len))]
#![feature(const_cow_is_borrowed)]
#![feature(const_convert)]
#![feature(const_size_of_val)]
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2 changes: 1 addition & 1 deletion library/alloc/tests/lib.rs
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Expand Up @@ -32,7 +32,7 @@
#![feature(slice_group_by)]
#![feature(slice_partition_dedup)]
#![feature(string_remove_matches)]
#![feature(const_btree_new)]
#![feature(const_btree_len)]
#![feature(const_default_impls)]
#![feature(const_trait_impl)]
#![feature(const_str_from_utf8)]
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2 changes: 0 additions & 2 deletions src/test/ui/consts/issue-88071.rs
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Expand Up @@ -2,8 +2,6 @@
//
// regression test for #88071

#![feature(const_btree_new)]

use std::collections::BTreeMap;

pub struct CustomMap<K, V>(BTreeMap<K, V>);
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13 changes: 12 additions & 1 deletion src/tools/clippy/clippy_utils/src/qualify_min_const_fn.rs
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Expand Up @@ -367,10 +367,21 @@ fn is_const_fn(tcx: TyCtxt<'_>, def_id: DefId, msrv: Option<RustcVersion>) -> bo
// Checking MSRV is manually necessary because `rustc` has no such concept. This entire
// function could be removed if `rustc` provided a MSRV-aware version of `is_const_fn`.
// as a part of an unimplemented MSRV check https://github.com/rust-lang/rust/issues/65262.

// HACK(nilstrieb): CURRENT_RUSTC_VERSION can return versions like 1.66.0-dev. `rustc-semver` doesn't accept
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@est31 might be good to followup on this and figure out what's happening here -- we probably shouldn't be returning -dev in the version, since we don't include -nightly for example.

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Yeah the -dev is being returned because the CFG_VERSION env var contains it. That env var itself is set by the bootstrap tooling (and it also adds -nightly postfixes FTR). I originally went with the most simple code and didn't strip the postfix because that would have involved parsing the version number (like this code is doing). I'd thought it wouldn't be much of a problem, it seems that most of the tooling could handle the postfix.

I like the -nightly postfix because it gives it a notion of preliminarity: attention that compiler has not been released yet, the stabilization might be reverted (like never has been multiple times, or let chains very recently). Also, sometimes that number can lie: for example right now the cast_const function is shown to be stabilized on 1.66.0-nightly in the nightly docs:

Screenshot_20220926_083953

Even though it's actually been stabilized in 1.65.0, and beta already correctly shows this:

Screenshot_20220926_084224

Admittedly, this only occurs during a ~one week period during the release cycle, in this particular instance because #102051 hasn't been merged yet to master, which changes the placeholder to 1.65.0. But I think the -nightly postfix helps here in this instance, makes people more cautious that it might be wrong. Or idk.

So I'm not that unhappy with the current postfix, but I'm willing to remove it, if it's really not wanted. #101772 has introduced the rust_version_symbol function, so there is a centralized place to change it, to add code not dissimilar from this one.

// the `-dev` version number so we have to strip it off.
let short_version = since
.as_str()
.split('-')
.next()
.expect("rustc_attr::StabilityLevel::Stable::since` is empty");

let since = rustc_span::Symbol::intern(short_version);

crate::meets_msrv(
msrv,
RustcVersion::parse(since.as_str())
.expect("`rustc_attr::StabilityLevel::Stable::since` is ill-formatted"),
.unwrap_or_else(|err| panic!("`rustc_attr::StabilityLevel::Stable::since` is ill-formatted: `{since}`, {err:?}")),
)
} else {
// Unstable const fn with the feature enabled.
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6 changes: 3 additions & 3 deletions src/tools/clippy/tests/ui/crashes/ice-7126.rs
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@@ -1,13 +1,13 @@
// This test requires a feature gated const fn and will stop working in the future.

#![feature(const_btree_new)]
#![feature(const_btree_len)]

use std::collections::BTreeMap;

struct Foo(BTreeMap<i32, i32>);
struct Foo(usize);
impl Foo {
fn new() -> Self {
Self(BTreeMap::new())
Self(BTreeMap::len(&BTreeMap::<u8, u8>::new()))
}
}

Expand Down