From 853333d4bdc7570b74e4bf02d506c2951a9d3e4b Mon Sep 17 00:00:00 2001 From: Oli Scherer Date: Tue, 15 Jul 2025 09:57:44 +0000 Subject: [PATCH] constify `Option` methods --- library/core/src/option.rs | 137 ++++++++++++++++++++++++++----------- 1 file changed, 97 insertions(+), 40 deletions(-) diff --git a/library/core/src/option.rs b/library/core/src/option.rs index 9f432758a66f6..7633429fc5c0d 100644 --- a/library/core/src/option.rs +++ b/library/core/src/option.rs @@ -577,6 +577,7 @@ #![stable(feature = "rust1", since = "1.0.0")] use crate::iter::{self, FusedIterator, TrustedLen}; +use crate::marker::Destruct; use crate::ops::{self, ControlFlow, Deref, DerefMut}; use crate::panicking::{panic, panic_display}; use crate::pin::Pin; @@ -649,7 +650,8 @@ impl Option { #[must_use] #[inline] #[stable(feature = "is_some_and", since = "1.70.0")] - pub fn is_some_and(self, f: impl FnOnce(T) -> bool) -> bool { + #[rustc_const_unstable(feature = "const_option_ops", issue = "143956")] + pub const fn is_some_and(self, f: impl ~const FnOnce(T) -> bool + ~const Destruct) -> bool { match self { None => false, Some(x) => f(x), @@ -697,7 +699,8 @@ impl Option { #[must_use] #[inline] #[stable(feature = "is_none_or", since = "1.82.0")] - pub fn is_none_or(self, f: impl FnOnce(T) -> bool) -> bool { + #[rustc_const_unstable(feature = "const_option_ops", issue = "143956")] + pub const fn is_none_or(self, f: impl ~const FnOnce(T) -> bool + ~const Destruct) -> bool { match self { None => true, Some(x) => f(x), @@ -1023,7 +1026,12 @@ impl Option { /// ``` #[inline] #[stable(feature = "rust1", since = "1.0.0")] - pub fn unwrap_or(self, default: T) -> T { + #[rustc_allow_const_fn_unstable(const_precise_live_drops)] + #[rustc_const_unstable(feature = "const_option_ops", issue = "143956")] + pub const fn unwrap_or(self, default: T) -> T + where + T: ~const Destruct, + { match self { Some(x) => x, None => default, @@ -1042,9 +1050,10 @@ impl Option { #[inline] #[track_caller] #[stable(feature = "rust1", since = "1.0.0")] - pub fn unwrap_or_else(self, f: F) -> T + #[rustc_const_unstable(feature = "const_option_ops", issue = "143956")] + pub const fn unwrap_or_else(self, f: F) -> T where - F: FnOnce() -> T, + F: ~const FnOnce() -> T + ~const Destruct, { match self { Some(x) => x, @@ -1073,9 +1082,10 @@ impl Option { /// [`FromStr`]: crate::str::FromStr #[inline] #[stable(feature = "rust1", since = "1.0.0")] - pub fn unwrap_or_default(self) -> T + #[rustc_const_unstable(feature = "const_option_ops", issue = "143956")] + pub const fn unwrap_or_default(self) -> T where - T: Default, + T: ~const Default, { match self { Some(x) => x, @@ -1139,9 +1149,10 @@ impl Option { /// ``` #[inline] #[stable(feature = "rust1", since = "1.0.0")] - pub fn map(self, f: F) -> Option + #[rustc_const_unstable(feature = "const_option_ops", issue = "143956")] + pub const fn map(self, f: F) -> Option where - F: FnOnce(T) -> U, + F: ~const FnOnce(T) -> U + ~const Destruct, { match self { Some(x) => Some(f(x)), @@ -1169,7 +1180,11 @@ impl Option { /// ``` #[inline] #[stable(feature = "result_option_inspect", since = "1.76.0")] - pub fn inspect(self, f: F) -> Self { + #[rustc_const_unstable(feature = "const_option_ops", issue = "143956")] + pub const fn inspect(self, f: F) -> Self + where + F: ~const FnOnce(&T) + ~const Destruct, + { if let Some(ref x) = self { f(x); } @@ -1198,9 +1213,11 @@ impl Option { #[inline] #[stable(feature = "rust1", since = "1.0.0")] #[must_use = "if you don't need the returned value, use `if let` instead"] - pub fn map_or(self, default: U, f: F) -> U + #[rustc_const_unstable(feature = "const_option_ops", issue = "143956")] + pub const fn map_or(self, default: U, f: F) -> U where - F: FnOnce(T) -> U, + F: ~const FnOnce(T) -> U + ~const Destruct, + U: ~const Destruct, { match self { Some(t) => f(t), @@ -1243,10 +1260,11 @@ impl Option { /// ``` #[inline] #[stable(feature = "rust1", since = "1.0.0")] - pub fn map_or_else(self, default: D, f: F) -> U + #[rustc_const_unstable(feature = "const_option_ops", issue = "143956")] + pub const fn map_or_else(self, default: D, f: F) -> U where - D: FnOnce() -> U, - F: FnOnce(T) -> U, + D: ~const FnOnce() -> U + ~const Destruct, + F: ~const FnOnce(T) -> U + ~const Destruct, { match self { Some(t) => f(t), @@ -1273,10 +1291,11 @@ impl Option { /// [default value]: Default::default #[inline] #[unstable(feature = "result_option_map_or_default", issue = "138099")] - pub fn map_or_default(self, f: F) -> U + #[rustc_const_unstable(feature = "const_option_ops", issue = "143956")] + pub const fn map_or_default(self, f: F) -> U where - U: Default, - F: FnOnce(T) -> U, + U: ~const Default, + F: ~const FnOnce(T) -> U + ~const Destruct, { match self { Some(t) => f(t), @@ -1307,7 +1326,8 @@ impl Option { /// ``` #[inline] #[stable(feature = "rust1", since = "1.0.0")] - pub fn ok_or(self, err: E) -> Result { + #[rustc_const_unstable(feature = "const_option_ops", issue = "143956")] + pub const fn ok_or(self, err: E) -> Result { match self { Some(v) => Ok(v), None => Err(err), @@ -1332,9 +1352,10 @@ impl Option { /// ``` #[inline] #[stable(feature = "rust1", since = "1.0.0")] - pub fn ok_or_else(self, err: F) -> Result + #[rustc_const_unstable(feature = "const_option_ops", issue = "143956")] + pub const fn ok_or_else(self, err: F) -> Result where - F: FnOnce() -> E, + F: ~const FnOnce() -> E + ~const Destruct, { match self { Some(v) => Ok(v), @@ -1463,7 +1484,12 @@ impl Option { /// ``` #[inline] #[stable(feature = "rust1", since = "1.0.0")] - pub fn and(self, optb: Option) -> Option { + #[rustc_const_unstable(feature = "const_option_ops", issue = "143956")] + pub const fn and(self, optb: Option) -> Option + where + T: ~const Destruct, + U: ~const Destruct, + { match self { Some(_) => optb, None => None, @@ -1502,9 +1528,10 @@ impl Option { #[inline] #[stable(feature = "rust1", since = "1.0.0")] #[rustc_confusables("flat_map", "flatmap")] - pub fn and_then(self, f: F) -> Option + #[rustc_const_unstable(feature = "const_option_ops", issue = "143956")] + pub const fn and_then(self, f: F) -> Option where - F: FnOnce(T) -> Option, + F: ~const FnOnce(T) -> Option + ~const Destruct, { match self { Some(x) => f(x), @@ -1538,9 +1565,11 @@ impl Option { /// [`Some(t)`]: Some #[inline] #[stable(feature = "option_filter", since = "1.27.0")] - pub fn filter

(self, predicate: P) -> Self + #[rustc_const_unstable(feature = "const_option_ops", issue = "143956")] + pub const fn filter

(self, predicate: P) -> Self where - P: FnOnce(&T) -> bool, + P: ~const FnOnce(&T) -> bool + ~const Destruct, + T: ~const Destruct, { if let Some(x) = self { if predicate(&x) { @@ -1579,7 +1608,11 @@ impl Option { /// ``` #[inline] #[stable(feature = "rust1", since = "1.0.0")] - pub fn or(self, optb: Option) -> Option { + #[rustc_const_unstable(feature = "const_option_ops", issue = "143956")] + pub const fn or(self, optb: Option) -> Option + where + T: ~const Destruct, + { match self { x @ Some(_) => x, None => optb, @@ -1601,9 +1634,13 @@ impl Option { /// ``` #[inline] #[stable(feature = "rust1", since = "1.0.0")] - pub fn or_else(self, f: F) -> Option + #[rustc_const_unstable(feature = "const_option_ops", issue = "143956")] + pub const fn or_else(self, f: F) -> Option where - F: FnOnce() -> Option, + F: ~const FnOnce() -> Option + ~const Destruct, + //FIXME(const_hack): this `T: ~const Destruct` is unnecessary, but even precise live drops can't tell + // no value of type `T` gets dropped here + T: ~const Destruct, { match self { x @ Some(_) => x, @@ -1634,7 +1671,11 @@ impl Option { /// ``` #[inline] #[stable(feature = "option_xor", since = "1.37.0")] - pub fn xor(self, optb: Option) -> Option { + #[rustc_const_unstable(feature = "const_option_ops", issue = "143956")] + pub const fn xor(self, optb: Option) -> Option + where + T: ~const Destruct, + { match (self, optb) { (a @ Some(_), None) => a, (None, b @ Some(_)) => b, @@ -1668,7 +1709,11 @@ impl Option { #[must_use = "if you intended to set a value, consider assignment instead"] #[inline] #[stable(feature = "option_insert", since = "1.53.0")] - pub fn insert(&mut self, value: T) -> &mut T { + #[rustc_const_unstable(feature = "const_option_ops", issue = "143956")] + pub const fn insert(&mut self, value: T) -> &mut T + where + T: ~const Destruct, + { *self = Some(value); // SAFETY: the code above just filled the option @@ -1720,9 +1765,10 @@ impl Option { /// ``` #[inline] #[stable(feature = "option_get_or_insert_default", since = "1.83.0")] - pub fn get_or_insert_default(&mut self) -> &mut T + #[rustc_const_unstable(feature = "const_option_ops", issue = "143956")] + pub const fn get_or_insert_default(&mut self) -> &mut T where - T: Default, + T: ~const Default + ~const Destruct, { self.get_or_insert_with(T::default) } @@ -1746,9 +1792,11 @@ impl Option { /// ``` #[inline] #[stable(feature = "option_entry", since = "1.20.0")] - pub fn get_or_insert_with(&mut self, f: F) -> &mut T + #[rustc_const_unstable(feature = "const_option_ops", issue = "143956")] + pub const fn get_or_insert_with(&mut self, f: F) -> &mut T where - F: FnOnce() -> T, + F: ~const FnOnce() -> T + ~const Destruct, + T: ~const Destruct, { if let None = self { *self = Some(f()); @@ -1812,9 +1860,10 @@ impl Option { /// ``` #[inline] #[stable(feature = "option_take_if", since = "1.80.0")] - pub fn take_if

(&mut self, predicate: P) -> Option + #[rustc_const_unstable(feature = "const_option_ops", issue = "143956")] + pub const fn take_if

(&mut self, predicate: P) -> Option where - P: FnOnce(&mut T) -> bool, + P: ~const FnOnce(&mut T) -> bool + ~const Destruct, { if self.as_mut().map_or(false, predicate) { self.take() } else { None } } @@ -1859,7 +1908,12 @@ impl Option { /// assert_eq!(x.zip(z), None); /// ``` #[stable(feature = "option_zip_option", since = "1.46.0")] - pub fn zip(self, other: Option) -> Option<(T, U)> { + #[rustc_const_unstable(feature = "const_option_ops", issue = "143956")] + pub const fn zip(self, other: Option) -> Option<(T, U)> + where + T: ~const Destruct, + U: ~const Destruct, + { match (self, other) { (Some(a), Some(b)) => Some((a, b)), _ => None, @@ -1895,9 +1949,12 @@ impl Option { /// assert_eq!(x.zip_with(None, Point::new), None); /// ``` #[unstable(feature = "option_zip", issue = "70086")] - pub fn zip_with(self, other: Option, f: F) -> Option + #[rustc_const_unstable(feature = "const_option_ops", issue = "143956")] + pub const fn zip_with(self, other: Option, f: F) -> Option where - F: FnOnce(T, U) -> R, + F: ~const FnOnce(T, U) -> R + ~const Destruct, + T: ~const Destruct, + U: ~const Destruct, { match (self, other) { (Some(a), Some(b)) => Some(f(a, b)),