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Stabilize const_option
This makes the following API stable in const contexts: impl<T> Option<T> { pub const fn as_mut(&mut self) -> Option<&mut T>; pub const fn expect(self, msg: &str) -> T; pub const fn unwrap(self) -> T; pub const unsafe fn unwrap_unchecked(self) -> T; pub const fn take(&mut self) -> Option<T>; pub const fn replace(&mut self, value: T) -> Option<T>; } impl<T> Option<&T> { pub const fn copied(self) -> Option<T> where T: Copy; } impl<T> Option<&mut T> { pub const fn copied(self) -> Option<T> where T: Copy; } impl<T, E> Option<Result<T, E>> { pub const fn transpose(self) -> Result<Option<T>, E> } impl<T> Option<Option<T>> { pub const fn flatten(self) -> Option<T>; } The following functions make use of the unstable `const_precise_live_drops` feature: - `expect` - `unwrap` - `unwrap_unchecked` - `transpose` - `flatten` Fixes: <#67441>
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14 files changed

+39
-29
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14 files changed

+39
-29
lines changed

‎compiler/rustc_middle/src/lib.rs

-1
Original file line numberDiff line numberDiff line change
@@ -37,7 +37,6 @@
3737
#![feature(box_as_ptr)]
3838
#![feature(box_patterns)]
3939
#![feature(closure_track_caller)]
40-
#![feature(const_option)]
4140
#![feature(const_type_name)]
4241
#![feature(core_intrinsics)]
4342
#![feature(coroutines)]

‎compiler/rustc_serialize/src/lib.rs

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@@ -10,7 +10,6 @@
1010
test(attr(allow(unused_variables), deny(warnings)))
1111
)]
1212
#![doc(rust_logo)]
13-
#![feature(const_option)]
1413
#![feature(core_intrinsics)]
1514
#![feature(min_specialization)]
1615
#![feature(never_type)]

‎library/alloc/src/lib.rs

-1
Original file line numberDiff line numberDiff line change
@@ -112,7 +112,6 @@
112112
#![feature(const_eval_select)]
113113
#![feature(const_heap)]
114114
#![feature(const_maybe_uninit_write)]
115-
#![feature(const_option)]
116115
#![feature(const_pin)]
117116
#![feature(const_size_of_val)]
118117
#![feature(core_intrinsics)]

‎library/core/src/array/ascii.rs

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@@ -9,7 +9,6 @@ impl<const N: usize> [u8; N] {
99
///
1010
/// ```
1111
/// #![feature(ascii_char)]
12-
/// #![feature(const_option)]
1312
///
1413
/// const HEX_DIGITS: [std::ascii::Char; 16] =
1514
/// *b"0123456789abcdef".as_ascii().unwrap();

‎library/core/src/lib.rs

-1
Original file line numberDiff line numberDiff line change
@@ -135,7 +135,6 @@
135135
#![feature(const_maybe_uninit_assume_init)]
136136
#![feature(const_nonnull_new)]
137137
#![feature(const_num_midpoint)]
138-
#![feature(const_option)]
139138
#![feature(const_option_ext)]
140139
#![feature(const_pin)]
141140
#![feature(const_pointer_is_aligned)]

‎library/core/src/option.rs

+21-11
Original file line numberDiff line numberDiff line change
@@ -723,7 +723,8 @@ impl<T> Option<T> {
723723
/// ```
724724
#[inline]
725725
#[stable(feature = "rust1", since = "1.0.0")]
726-
#[rustc_const_unstable(feature = "const_option", issue = "67441")]
726+
#[cfg_attr(bootstrap, rustc_allow_const_fn_unstable(const_mut_refs))]
727+
#[rustc_const_stable(feature = "const_option", since = "CURRENT_RUSTC_VERSION")]
727728
pub const fn as_mut(&mut self) -> Option<&mut T> {
728729
match *self {
729730
Some(ref mut x) => Some(x),
@@ -924,7 +925,8 @@ impl<T> Option<T> {
924925
#[track_caller]
925926
#[stable(feature = "rust1", since = "1.0.0")]
926927
#[cfg_attr(not(test), rustc_diagnostic_item = "option_expect")]
927-
#[rustc_const_unstable(feature = "const_option", issue = "67441")]
928+
#[rustc_allow_const_fn_unstable(const_precise_live_drops)]
929+
#[rustc_const_stable(feature = "const_option", since = "CURRENT_RUSTC_VERSION")]
928930
pub const fn expect(self, msg: &str) -> T {
929931
match self {
930932
Some(val) => val,
@@ -962,7 +964,8 @@ impl<T> Option<T> {
962964
#[track_caller]
963965
#[stable(feature = "rust1", since = "1.0.0")]
964966
#[cfg_attr(not(test), rustc_diagnostic_item = "option_unwrap")]
965-
#[rustc_const_unstable(feature = "const_option", issue = "67441")]
967+
#[rustc_allow_const_fn_unstable(const_precise_live_drops)]
968+
#[rustc_const_stable(feature = "const_option", since = "CURRENT_RUSTC_VERSION")]
966969
pub const fn unwrap(self) -> T {
967970
match self {
968971
Some(val) => val,
@@ -1069,7 +1072,8 @@ impl<T> Option<T> {
10691072
#[inline]
10701073
#[track_caller]
10711074
#[stable(feature = "option_result_unwrap_unchecked", since = "1.58.0")]
1072-
#[rustc_const_unstable(feature = "const_option", issue = "67441")]
1075+
#[rustc_allow_const_fn_unstable(const_precise_live_drops)]
1076+
#[rustc_const_stable(feature = "const_option", since = "CURRENT_RUSTC_VERSION")]
10731077
pub const unsafe fn unwrap_unchecked(self) -> T {
10741078
match self {
10751079
Some(val) => val,
@@ -1712,7 +1716,9 @@ impl<T> Option<T> {
17121716
/// ```
17131717
#[inline]
17141718
#[stable(feature = "rust1", since = "1.0.0")]
1715-
#[rustc_const_unstable(feature = "const_option", issue = "67441")]
1719+
#[cfg_attr(bootstrap, rustc_allow_const_fn_unstable(const_mut_refs))]
1720+
#[rustc_allow_const_fn_unstable(const_replace)] // todo: drop if we don't get stable const_replace
1721+
#[rustc_const_stable(feature = "const_option", since = "CURRENT_RUSTC_VERSION")]
17161722
pub const fn take(&mut self) -> Option<T> {
17171723
// FIXME(const-hack) replace `mem::replace` by `mem::take` when the latter is const ready
17181724
mem::replace(self, None)
@@ -1769,8 +1775,10 @@ impl<T> Option<T> {
17691775
/// assert_eq!(old, None);
17701776
/// ```
17711777
#[inline]
1772-
#[rustc_const_unstable(feature = "const_option", issue = "67441")]
17731778
#[stable(feature = "option_replace", since = "1.31.0")]
1779+
#[cfg_attr(bootstrap, rustc_allow_const_fn_unstable(const_mut_refs))]
1780+
#[rustc_allow_const_fn_unstable(const_replace)] // todo: drop if we don't get stable const_replace
1781+
#[rustc_const_stable(feature = "const_option", since = "CURRENT_RUSTC_VERSION")]
17741782
pub const fn replace(&mut self, value: T) -> Option<T> {
17751783
mem::replace(self, Some(value))
17761784
}
@@ -1878,7 +1886,7 @@ impl<T> Option<&T> {
18781886
/// ```
18791887
#[must_use = "`self` will be dropped if the result is not used"]
18801888
#[stable(feature = "copied", since = "1.35.0")]
1881-
#[rustc_const_unstable(feature = "const_option", issue = "67441")]
1889+
#[rustc_const_stable(feature = "const_option", since = "CURRENT_RUSTC_VERSION")]
18821890
pub const fn copied(self) -> Option<T>
18831891
where
18841892
T: Copy,
@@ -1931,7 +1939,8 @@ impl<T> Option<&mut T> {
19311939
/// ```
19321940
#[must_use = "`self` will be dropped if the result is not used"]
19331941
#[stable(feature = "copied", since = "1.35.0")]
1934-
#[rustc_const_unstable(feature = "const_option", issue = "67441")]
1942+
#[cfg_attr(bootstrap, rustc_allow_const_fn_unstable(const_mut_refs))]
1943+
#[rustc_const_stable(feature = "const_option", since = "CURRENT_RUSTC_VERSION")]
19351944
pub const fn copied(self) -> Option<T>
19361945
where
19371946
T: Copy,
@@ -1986,7 +1995,8 @@ impl<T, E> Option<Result<T, E>> {
19861995
/// ```
19871996
#[inline]
19881997
#[stable(feature = "transpose_result", since = "1.33.0")]
1989-
#[rustc_const_unstable(feature = "const_option", issue = "67441")]
1998+
#[rustc_allow_const_fn_unstable(const_precise_live_drops)]
1999+
#[rustc_const_stable(feature = "const_option", since = "CURRENT_RUSTC_VERSION")]
19902000
pub const fn transpose(self) -> Result<Option<T>, E> {
19912001
match self {
19922002
Some(Ok(x)) => Ok(Some(x)),
@@ -2009,7 +2019,6 @@ const fn unwrap_failed() -> ! {
20092019
#[cfg_attr(feature = "panic_immediate_abort", inline)]
20102020
#[cold]
20112021
#[track_caller]
2012-
#[rustc_const_unstable(feature = "const_option", issue = "67441")]
20132022
const fn expect_failed(msg: &str) -> ! {
20142023
panic_display(&msg)
20152024
}
@@ -2534,7 +2543,8 @@ impl<T> Option<Option<T>> {
25342543
/// ```
25352544
#[inline]
25362545
#[stable(feature = "option_flattening", since = "1.40.0")]
2537-
#[rustc_const_unstable(feature = "const_option", issue = "67441")]
2546+
#[rustc_allow_const_fn_unstable(const_precise_live_drops)]
2547+
#[rustc_const_stable(feature = "const_option", since = "CURRENT_RUSTC_VERSION")]
25382548
pub const fn flatten(self) -> Option<T> {
25392549
// FIXME(const-hack): could be written with `and_then`
25402550
match self {

‎library/core/src/ptr/non_null.rs

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Original file line numberDiff line numberDiff line change
@@ -1210,7 +1210,6 @@ impl<T: ?Sized> NonNull<T> {
12101210
///
12111211
/// ```
12121212
/// #![feature(const_nonnull_new)]
1213-
/// #![feature(const_option)]
12141213
/// #![feature(const_pointer_is_aligned)]
12151214
/// use std::ptr::NonNull;
12161215
///
@@ -1263,7 +1262,6 @@ impl<T: ?Sized> NonNull<T> {
12631262
///
12641263
/// ```
12651264
/// #![feature(const_pointer_is_aligned)]
1266-
/// #![feature(const_option)]
12671265
/// #![feature(const_nonnull_new)]
12681266
/// use std::ptr::NonNull;
12691267
///

‎library/core/src/time.rs

-1
Original file line numberDiff line numberDiff line change
@@ -626,7 +626,6 @@ impl Duration {
626626
/// ```
627627
#[stable(feature = "duration_abs_diff", since = "1.81.0")]
628628
#[rustc_const_stable(feature = "duration_abs_diff", since = "1.81.0")]
629-
#[rustc_allow_const_fn_unstable(const_option)]
630629
#[must_use = "this returns the result of the operation, \
631630
without modifying the original"]
632631
#[inline]

‎library/core/tests/lib.rs

-1
Original file line numberDiff line numberDiff line change
@@ -25,7 +25,6 @@
2525
#![feature(const_ipv6)]
2626
#![feature(const_likely)]
2727
#![feature(const_nonnull_new)]
28-
#![feature(const_option)]
2928
#![feature(const_option_ext)]
3029
#![feature(const_pin)]
3130
#![feature(const_pointer_is_aligned)]

‎src/tools/clippy/tests/ui/doc/doc-fixable.fixed

+1-1
Original file line numberDiff line numberDiff line change
@@ -3,7 +3,7 @@
33

44
#![allow(dead_code, incomplete_features)]
55
#![warn(clippy::doc_markdown)]
6-
#![feature(custom_inner_attributes, generic_const_exprs, const_option)]
6+
#![feature(custom_inner_attributes, generic_const_exprs)]
77
#![rustfmt::skip]
88

99
/// The `foo_bar` function does _nothing_. See also `foo::bar`. (note the dot there)

‎src/tools/clippy/tests/ui/doc/doc-fixable.rs

+1-1
Original file line numberDiff line numberDiff line change
@@ -3,7 +3,7 @@
33
44
#![allow(dead_code, incomplete_features)]
55
#![warn(clippy::doc_markdown)]
6-
#![feature(custom_inner_attributes, generic_const_exprs, const_option)]
6+
#![feature(custom_inner_attributes, generic_const_exprs)]
77
#![rustfmt::skip]
88

99
/// The foo_bar function does _nothing_. See also foo::bar. (note the dot there)

‎src/tools/miri/src/lib.rs

-1
Original file line numberDiff line numberDiff line change
@@ -1,6 +1,5 @@
11
#![feature(rustc_private)]
22
#![feature(cell_update)]
3-
#![feature(const_option)]
43
#![feature(float_gamma)]
54
#![feature(map_try_insert)]
65
#![feature(never_type)]

‎tests/ui/consts/const-unwrap.rs

+7-3
Original file line numberDiff line numberDiff line change
@@ -1,11 +1,15 @@
11
//@ check-fail
2-
3-
#![feature(const_option)]
2+
// Verify that panicking `const_option` methods do the correct thing
43

54
const FOO: i32 = Some(42i32).unwrap();
65

76
const BAR: i32 = Option::<i32>::None.unwrap();
8-
//~^ERROR: evaluation of constant value failed
7+
//~^ ERROR: evaluation of constant value failed
8+
//~| NOTE: the evaluated program panicked
9+
10+
const BAZ: i32 = Option::<i32>::None.expect("absolutely not!");
11+
//~^ ERROR: evaluation of constant value failed
12+
//~| NOTE: absolutely not!
913

1014
fn main() {
1115
println!("{}", FOO);

‎tests/ui/consts/const-unwrap.stderr

+9-3
Original file line numberDiff line numberDiff line change
@@ -1,9 +1,15 @@
11
error[E0080]: evaluation of constant value failed
2-
--> $DIR/const-unwrap.rs:7:18
2+
--> $DIR/const-unwrap.rs:6:18
33
|
44
LL | const BAR: i32 = Option::<i32>::None.unwrap();
5-
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the evaluated program panicked at 'called `Option::unwrap()` on a `None` value', $DIR/const-unwrap.rs:7:38
5+
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the evaluated program panicked at 'called `Option::unwrap()` on a `None` value', $DIR/const-unwrap.rs:6:38
66

7-
error: aborting due to 1 previous error
7+
error[E0080]: evaluation of constant value failed
8+
--> $DIR/const-unwrap.rs:10:18
9+
|
10+
LL | const BAZ: i32 = Option::<i32>::None.expect("absolutely not!");
11+
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the evaluated program panicked at 'absolutely not!', $DIR/const-unwrap.rs:10:38
12+
13+
error: aborting due to 2 previous errors
814

915
For more information about this error, try `rustc --explain E0080`.

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