constify `Option` methods by oli-obk · Pull Request #143967 · rust-lang/rust

oli-obk · 2025-07-15T14:13:06Z

tracking issue: #143956

these unblock making PartialOrd and Ord const without resorting to inlining some of these at call sites.

oli-obk · 2025-07-15T14:13:39Z

library/core/src/option.rs

+        T: ~const Destruct,
    {
        match self {
            x @ Some(_) => x,


This pattern was introduced in #116481 because it optimizes better.

fee1-dead · 2025-07-15T17:11:04Z

library/core/src/option.rs

+        //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


I have a feeling this will nerdsnipe me hard.

Here's how code is currently generated

#![feature(const_destruct)] #![feature(const_trait_impl)] use std::marker::Destruct; pub const fn opt_or_else<T, F>(this: Option<T>, f: F) -> Option<T> where F: ~const Destruct + ~const FnOnce() -> Option<T>, T: ~const Destruct { match this { x @ Some(_) => x, None => f() } }

// MIR FOR CTFE fn opt_or_else(_1: Option<T>, _2: F) -> Option<T> { debug this => _1; debug f => _2; let mut _0: std::option::Option<T>; let mut _3: isize; let _4: std::option::Option<T>; let mut _5: F; let mut _6: (); let mut _7: bool; let mut _8: bool; scope 1 { debug x => _4; } bb0: { _8 = const false; _7 = const false; _8 = const true; _7 = const true; _3 = discriminant(_1); switchInt(move _3) -> [0: bb2, 1: bb3, otherwise: bb1]; } bb1: { unreachable; } bb2: { StorageLive(_5); _7 = const false; _5 = move _2; StorageLive(_6); _6 = (); ConstEvalCounter; _0 = <F as FnOnce<()>>::call_once(move _5, move _6) -> [return: bb4, unwind: bb12]; } bb3: { StorageLive(_4); _8 = const false; _4 = move _1; _0 = move _4; StorageDead(_4); goto -> bb9; } bb4: { StorageDead(_6); StorageDead(_5); goto -> bb9; } bb5: { switchInt(copy _8) -> [0: bb6, otherwise: bb10]; } bb6: { return; } bb7 (cleanup): { resume; } bb8: { drop(_2) -> [return: bb5, unwind: bb12]; } bb9: { switchInt(copy _7) -> [0: bb5, otherwise: bb8]; } bb10: { drop(_1) -> [return: bb6, unwind: bb7]; } bb11 (cleanup): { drop(_1) -> [return: bb7, unwind terminate(cleanup)]; } bb12 (cleanup): { switchInt(copy _8) -> [0: bb7, otherwise: bb11]; } }

looks like it tries to drop self at the None arm, which is just weird.

fee1-dead

r=me after nit

fee1-dead · 2025-07-17T00:52:57Z

library/core/src/option.rs

    #[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 Destruct + ~const FnOnce(T) -> bool) -> bool {


I think we should put FnOnce first, here and elsewhere in the PR. the destruct bound is noisy and likely to make it harder for someone to read the code.

oli-obk · 2025-07-17T09:11:57Z

@bors r=fee1-dead

bors · 2025-07-17T09:11:59Z

📌 Commit 853333d has been approved by fee1-dead

It is now in the queue for this repository.

…e1-dead constify `Option` methods r? `@fee1-dead` tracking issue: rust-lang#143956 these unblock making `PartialOrd` and `Ord` const without resorting to inlining some of these at call sites.

…e1-dead constify `Option` methods r? ``@fee1-dead`` tracking issue: rust-lang#143956 these unblock making `PartialOrd` and `Ord` const without resorting to inlining some of these at call sites.

Rollup of 15 pull requests Successful merges: - #142300 (Disable `tests/run-make/mte-ffi` because no CI runners have MTE extensions enabled) - #143271 (Store the type of each GVN value) - #143293 (fix `-Zsanitizer=kcfi` on `#[naked]` functions) - #143719 (Emit warning when there is no space between `-o` and arg) - #143833 (Ban projecting into SIMD types [MCP838]) - #143846 (pass --gc-sections if -Zexport-executable-symbols is enabled and improve tests) - #143879 (parse `const trait Trait`) - #143891 (Port `#[coverage]` to the new attribute system) - #143967 (constify `Option` methods) - #143985 (rustc_public: de-StableMIR-ize) - #144008 (Fix false positive double negations with macro invocation) - #144010 (Boostrap: add warning on `optimize = false`) - #144034 (tests: Test line number in debuginfo for diverging function calls) - #144049 (rustc-dev-guide subtree update) - #144056 (Copy GCC sources into the build directory even outside CI) r? `@ghost` `@rustbot` modify labels: rollup

…e1-dead constify `Option` methods r? ```@fee1-dead``` tracking issue: rust-lang#143956 these unblock making `PartialOrd` and `Ord` const without resorting to inlining some of these at call sites.

Rollup of 12 pull requests Successful merges: - #142300 (Disable `tests/run-make/mte-ffi` because no CI runners have MTE extensions enabled) - #143271 (Store the type of each GVN value) - #143293 (fix `-Zsanitizer=kcfi` on `#[naked]` functions) - #143719 (Emit warning when there is no space between `-o` and arg) - #143846 (pass --gc-sections if -Zexport-executable-symbols is enabled and improve tests) - #143891 (Port `#[coverage]` to the new attribute system) - #143967 (constify `Option` methods) - #144008 (Fix false positive double negations with macro invocation) - #144010 (Boostrap: add warning on `optimize = false`) - #144034 (tests: Test line number in debuginfo for diverging function calls) - #144049 (rustc-dev-guide subtree update) - #144056 (Copy GCC sources into the build directory even outside CI) r? `@ghost` `@rustbot` modify labels: rollup

…e1-dead constify `Option` methods r? ````@fee1-dead```` tracking issue: rust-lang#143956 these unblock making `PartialOrd` and `Ord` const without resorting to inlining some of these at call sites.

…e1-dead constify `Option` methods r? `````@fee1-dead````` tracking issue: rust-lang#143956 these unblock making `PartialOrd` and `Ord` const without resorting to inlining some of these at call sites.

…e1-dead constify `Option` methods r? ``````@fee1-dead`````` tracking issue: rust-lang#143956 these unblock making `PartialOrd` and `Ord` const without resorting to inlining some of these at call sites.

Rollup of 11 pull requests Successful merges: - #142300 (Disable `tests/run-make/mte-ffi` because no CI runners have MTE extensions enabled) - #143271 (Store the type of each GVN value) - #143293 (fix `-Zsanitizer=kcfi` on `#[naked]` functions) - #143719 (Emit warning when there is no space between `-o` and arg) - #143846 (pass --gc-sections if -Zexport-executable-symbols is enabled and improve tests) - #143891 (Port `#[coverage]` to the new attribute system) - #143967 (constify `Option` methods) - #144008 (Fix false positive double negations with macro invocation) - #144010 (Boostrap: add warning on `optimize = false`) - #144049 (rustc-dev-guide subtree update) - #144056 (Copy GCC sources into the build directory even outside CI) r? `@ghost` `@rustbot` modify labels: rollup

Rollup merge of #143967 - oli-obk:const-option-methods, r=fee1-dead constify `Option` methods r? ```````@fee1-dead``````` tracking issue: #143956 these unblock making `PartialOrd` and `Ord` const without resorting to inlining some of these at call sites.

Rollup of 11 pull requests Successful merges: - rust-lang/rust#142300 (Disable `tests/run-make/mte-ffi` because no CI runners have MTE extensions enabled) - rust-lang/rust#143271 (Store the type of each GVN value) - rust-lang/rust#143293 (fix `-Zsanitizer=kcfi` on `#[naked]` functions) - rust-lang/rust#143719 (Emit warning when there is no space between `-o` and arg) - rust-lang/rust#143846 (pass --gc-sections if -Zexport-executable-symbols is enabled and improve tests) - rust-lang/rust#143891 (Port `#[coverage]` to the new attribute system) - rust-lang/rust#143967 (constify `Option` methods) - rust-lang/rust#144008 (Fix false positive double negations with macro invocation) - rust-lang/rust#144010 (Boostrap: add warning on `optimize = false`) - rust-lang/rust#144049 (rustc-dev-guide subtree update) - rust-lang/rust#144056 (Copy GCC sources into the build directory even outside CI) r? `@ghost` `@rustbot` modify labels: rollup

…e1-dead constify `Option` methods r? ```````@fee1-dead``````` tracking issue: rust-lang#143956 these unblock making `PartialOrd` and `Ord` const without resorting to inlining some of these at call sites.

…iaskrgr Rollup of 11 pull requests Successful merges: - rust-lang#142300 (Disable `tests/run-make/mte-ffi` because no CI runners have MTE extensions enabled) - rust-lang#143271 (Store the type of each GVN value) - rust-lang#143293 (fix `-Zsanitizer=kcfi` on `#[naked]` functions) - rust-lang#143719 (Emit warning when there is no space between `-o` and arg) - rust-lang#143846 (pass --gc-sections if -Zexport-executable-symbols is enabled and improve tests) - rust-lang#143891 (Port `#[coverage]` to the new attribute system) - rust-lang#143967 (constify `Option` methods) - rust-lang#144008 (Fix false positive double negations with macro invocation) - rust-lang#144010 (Boostrap: add warning on `optimize = false`) - rust-lang#144049 (rustc-dev-guide subtree update) - rust-lang#144056 (Copy GCC sources into the build directory even outside CI) r? `@ghost` `@rustbot` modify labels: rollup

…e1-dead constify `Option` methods r? ```````@fee1-dead``````` tracking issue: rust-lang#143956 these unblock making `PartialOrd` and `Ord` const without resorting to inlining some of these at call sites.

Rollup of 11 pull requests Successful merges: - rust-lang/rust#142300 (Disable `tests/run-make/mte-ffi` because no CI runners have MTE extensions enabled) - rust-lang/rust#143271 (Store the type of each GVN value) - rust-lang/rust#143293 (fix `-Zsanitizer=kcfi` on `#[naked]` functions) - rust-lang/rust#143719 (Emit warning when there is no space between `-o` and arg) - rust-lang/rust#143846 (pass --gc-sections if -Zexport-executable-symbols is enabled and improve tests) - rust-lang/rust#143891 (Port `#[coverage]` to the new attribute system) - rust-lang/rust#143967 (constify `Option` methods) - rust-lang/rust#144008 (Fix false positive double negations with macro invocation) - rust-lang/rust#144010 (Boostrap: add warning on `optimize = false`) - rust-lang/rust#144049 (rustc-dev-guide subtree update) - rust-lang/rust#144056 (Copy GCC sources into the build directory even outside CI) r? `@ghost` `@rustbot` modify labels: rollup

rustbot assigned fee1-dead Jul 15, 2025

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-libs Relevant to the library team, which will review and decide on the PR/issue. labels Jul 15, 2025

oli-obk commented Jul 15, 2025

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fee1-dead reviewed Jul 15, 2025

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fee1-dead requested changes Jul 17, 2025

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rustbot added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Jul 17, 2025

constify Option methods

853333d

oli-obk force-pushed the const-option-methods branch from 5d2acad to 853333d Compare July 17, 2025 09:11

bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Jul 17, 2025

fmease mentioned this pull request Jul 17, 2025

Rollup of 16 pull requests #144067

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fmease mentioned this pull request Jul 17, 2025

Rollup of 15 pull requests #144071

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Rollup of 12 pull requests #144075

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jhpratt mentioned this pull request Jul 18, 2025

Rollup of 12 pull requests #144102

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Rollup of 11 pull requests #144104

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Rollup of 10 pull requests #144106

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Rollup of 11 pull requests #144109

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bors merged commit a7009e9 into rust-lang:master Jul 18, 2025
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constify `Option` methods#143967

constify `Option` methods#143967
bors merged 1 commit intorust-lang:masterfrom
oli-obk:const-option-methods

oli-obk commented Jul 15, 2025 •

edited by rustbot

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		//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

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oli-obk commented Jul 15, 2025 •

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