Constify Eq, Ord, PartialOrd

[Randl]

Adds #[const_trait] and impls for Eq, Ord, PartialOrd. Impl for some other traits (e.g., slices and arrays) are blocked mainly on const closures (#106003).
For TypeId Ord we need const pointer comparison (#53020)
Tracking issue #143800

[rustbot]

r? @ibraheemdev

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[rustbot]

Some changes occurred to the intrinsics. Make sure the CTFE / Miri interpreter
gets adapted for the changes, if necessary.

cc @rust-lang/miri, @RalfJung, @oli-obk, @lcnr

[compiler-errors]

Squash this into one commit please

@rustbot author

[rustbot]

Reminder, once the PR becomes ready for a review, use @rustbot ready.

[Randl]

@rustbot ready

[ShoyuVanilla]

Not a review but just a question as I don't know the contexts very well 😅
I guess PartialEq and Eq could be const impl'd on tuples as well?

[Randl]

Fair enough, I've added impl const for tuples

[compiler-errors]

Sorry for taking a long time to review this. I'm actually somewhat uncomfortable by the scope of this PR. Could you please limit the number of types that this adds const impls for to just types that seem relevant for const programming?

Specifically, things like:

#[derive(Copy, Debug)]
#[derive_const(Clone, PartialEq, Eq)]
pub struct AllocError;

Don't seem really relevant here. I think this constification could probably just stick to constifying some impls for built-in types and other important types, and not just try to constify everything that can be constified in the standard library.

Also, since this adds new bounds to things, let's run a perf test.

@bors2 try @rust-timer queue

[compiler-errors]

@rustbot author

[clarfonthey]

FWIW, when I was working on this before I decided that I should do #144289 first, I figured that Eq actually shouldn't be const even though it would make bounds easier because ultimately, for a majority of users, the difference between const Eq and Eq is negligible since Eq itself doesn't contain any methods.

I guess it's a bit debatable, but I figured it wasn't worth distinguishing whether the Eq impl was const or not, just the PartialEq impl. It means that a lot of things will need Eq + [const] PartialEq instead of [const] Eq, but I figured that it would be better to make the former canonical than risk the former actually only being what's required despite the latter being easier to type.

[Randl]

risk the former actually only being what's required despite the latter

But the former implies the latter, right? There can't be Eq + [const] PartialEq that is not practically [const] Eq. So the difference is semantic and syntactic. From a semantic point of view, I see advantages of both approaches. x: [const] Eq makes sense because it means that we want to use Eq trait in a const context. On the other hand, if we interpret [const] trait as "all the methods of trait are const callable," then any trait without methods shouldn't be const. From a syntactic point of view, I think [const] Eq is clearly more convenient. We already have to sprinkle [const] Destruct all over the place; having to be even more verbose is a disadvantage in my opinion. I guess that there should be some decision regarding the best practice for no-method traits.

cc @oli-obk @RalfJung

[clarfonthey]

The issue is that you can't use Eq in const contexts: Eq is just a marker, and PartialEq is what you're actually using.

[Randl]

Well, at the risk of repeating myself, that depends on how you interpret [const] trait. If [const] trait means that "all methods of the trait are const callable" then you're 100% right. If it means "trait defines the functionality a particular type has that can be used in const context", then [const] Eq makes sense: it defines functionality that can be used in const (via methods of PartialEq, just like non-const version). This is purely semantic distinction.

[RalfJung]

I'm not involved much with const traits, Cc @fee1-dead

[fee1-dead]

T: [const] Eq is not so different from T: Eq + [const] PartialEq if everyone writes impl const Eq for MyType. On one hand, you can think of it as a silly additional requirement. There's no difference of impl const Eq from impl Eq if you know MyType implements const PartialEq.

On the other hand, it also seems silly to only allow derive_const for PartialEq and not Eq. It isn't too much to ask people to implement [const] Eq if they call a function that requires total equality in compile time.

I don't have a preference one way or the other.

[fee1-dead]

#143949 also caused some minor perf regressions, but so far nobody from wg-const-eval has commented on whether this is considered acceptable or not. Right now my understanding is that the goal is to constify everything, but there may need to be some changes with consteval since my suspicion is that the built-in stuff to allow these operators to work even without trait impls on primitives may now be slower with the const trait impls present and enabled.

Note that regressions on the PR you linked was ultimately triaged at the rollup.

Those negative perf results are due to making built-in traits const, which then increases the times where we have to check const conditions of traits, find implied predicates (super traits), etc. They're pretty much unavoidable, there's nothing much we can do, and we'll have to stick with it if we want libstd constified.

[oli-obk]

Some leftover syntax, otherwise lgtm

[rustbot]

This PR was rebased onto a different master commit! Check out the changes with our range-diff.

[oli-obk]

@bors r+

[bors]

📌 Commit f70c98f has been approved by oli-obk

It is now in the queue for this repository.

[jieyouxu]

@bors p=4 (rollup interleaving)

[bors]

⌛ Testing commit f70c98f with merge 953f713...

[rust-log-analyzer]

The job aarch64-apple failed! Check out the build log: (web) (plain enhanced) (plain)

Click to see the possible cause of the failure (guessed by this bot)

failures:

---- [codegen] tests/codegen-llvm/array-cmp.rs stdout ----

error: verification with 'FileCheck' failed
status: exit status: 1
command: "/Users/runner/work/rust/rust/build/aarch64-apple-darwin/ci-llvm/bin/FileCheck" "--input-file" "/Users/runner/work/rust/rust/build/aarch64-apple-darwin/test/codegen-llvm/array-cmp/array-cmp.ll" "/Users/runner/work/rust/rust/tests/codegen-llvm/array-cmp.rs" "--check-prefix=CHECK" "--allow-unused-prefixes" "--dump-input-context" "100"
stdout: none
--- stderr -------------------------------
/Users/runner/work/rust/rust/tests/codegen-llvm/array-cmp.rs:51:12: error: CHECK: expected string not found in input
 // CHECK: [[L10]]:
           ^
/Users/runner/work/rust/rust/build/aarch64-apple-darwin/test/codegen-llvm/array-cmp/array-cmp.ll:72:72: note: scanning from here
 br i1 %_5.i10.not.i.i.i, label %bb1.i, label %bb11.split.loop.exit15.i
                                                                       ^
/Users/runner/work/rust/rust/build/aarch64-apple-darwin/test/codegen-llvm/array-cmp/array-cmp.ll:72:72: note: with "L10" equal to "bb1.i"
 br i1 %_5.i10.not.i.i.i, label %bb1.i, label %bb11.split.loop.exit15.i
                                                                       ^
/Users/runner/work/rust/rust/build/aarch64-apple-darwin/test/codegen-llvm/array-cmp/array-cmp.ll:74:59: note: possible intended match here
_ZN4core5slice3cmp13chaining_impl17h5a59d2cbaa8836d3E.exit: ; preds = %bb6.i.i.1.i, %bb11.split.loop.exit13.i, %bb11.split.loop.exit15.i
                                                          ^

Input file: /Users/runner/work/rust/rust/build/aarch64-apple-darwin/test/codegen-llvm/array-cmp/array-cmp.ll
Check file: /Users/runner/work/rust/rust/tests/codegen-llvm/array-cmp.rs

-dump-input=help explains the following input dump.

Input was:
<<<<<<
            1: ; ModuleID = 'array_cmp.ea05bcb84312f8f9-cgu.0' 
            2: source_filename = "array_cmp.ea05bcb84312f8f9-cgu.0" 
            3: target datalayout = "e-m:o-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-n32:64-S128-Fn32" 
            4: target triple = "arm64-apple-macosx11.0.0" 
            5:  
            6: ; Function Attrs: mustprogress nofree norecurse nosync nounwind willreturn memory(none) uwtable 
            7: define noundef zeroext i1 @compare() unnamed_addr #0 { 
            8: start: 
            9:  ret i1 true 
           10: } 
           11:  
           12: ; Function Attrs: mustprogress nofree norecurse nosync nounwind willreturn memory(argmem: read, inaccessiblemem: readwrite) uwtable 
           13: define noundef zeroext i1 @array_of_tuple_le(ptr noalias noundef readonly align 2 captures(none) dereferenceable(8) %a, ptr noalias noundef readonly align 2 captures(none) dereferenceable(8) %b) unnamed_addr #1 personality ptr @rust_eh_personality { 
           14: start: 
           15:  tail call void @llvm.experimental.noalias.scope.decl(metadata !2) 
           16:  tail call void @llvm.experimental.noalias.scope.decl(metadata !5) 
           17:  tail call void @llvm.experimental.noalias.scope.decl(metadata !7) 
           18:  tail call void @llvm.experimental.noalias.scope.decl(metadata !10) 
           19:  tail call void @llvm.experimental.noalias.scope.decl(metadata !12) 
           20:  tail call void @llvm.experimental.noalias.scope.decl(metadata !15) 
           21:  tail call void @llvm.experimental.noalias.scope.decl(metadata !17) 
           22:  tail call void @llvm.experimental.noalias.scope.decl(metadata !20) 
           23:  %lhs.i.i.i.i = load i16, ptr %a, align 2, !alias.scope !22, !noalias !23, !noundef !24 
           24:  %rhs.i.i.i.i = load i16, ptr %b, align 2, !alias.scope !23, !noalias !22, !noundef !24 
           25:  %_5.i.i.i.i = icmp eq i16 %lhs.i.i.i.i, %rhs.i.i.i.i 
           26:  br i1 %_5.i.i.i.i, label %bb6.i.i.i, label %bb11.split.loop.exit13.i 
           27:  
           28: bb1.i: ; preds = %bb6.i.i.i 
           29:  %_17.1.i = getelementptr inbounds nuw i8, ptr %a, i64 4 
           30:  %_21.1.i = getelementptr inbounds nuw i8, ptr %b, i64 4 
           31:  tail call void @llvm.experimental.noalias.scope.decl(metadata !25) 
           32:  tail call void @llvm.experimental.noalias.scope.decl(metadata !27) 
           33:  tail call void @llvm.experimental.noalias.scope.decl(metadata !29) 
           34:  tail call void @llvm.experimental.noalias.scope.decl(metadata !31) 
           35:  tail call void @llvm.experimental.noalias.scope.decl(metadata !33) 
           36:  tail call void @llvm.experimental.noalias.scope.decl(metadata !35) 
           37:  %lhs.i.i.i.1.i = load i16, ptr %_17.1.i, align 2, !alias.scope !37, !noalias !38, !noundef !24 
           38:  %rhs.i.i.i.1.i = load i16, ptr %_21.1.i, align 2, !alias.scope !38, !noalias !37, !noundef !24 
           39:  %_5.i.i.i.1.i = icmp eq i16 %lhs.i.i.i.1.i, %rhs.i.i.i.1.i 
           40:  br i1 %_5.i.i.i.1.i, label %bb6.i.i.1.i, label %bb11.split.loop.exit13.i 
           41:  
           42: bb6.i.i.1.i: ; preds = %bb1.i 
           43:  %_10.i.i.1.i = getelementptr inbounds nuw i8, ptr %a, i64 6 
           44:  %_11.i.i.1.i = getelementptr inbounds nuw i8, ptr %b, i64 6 
           45:  tail call void @llvm.experimental.noalias.scope.decl(metadata !39) 
           46:  tail call void @llvm.experimental.noalias.scope.decl(metadata !42) 
           47:  %lhs.i8.i.i.1.i = load i16, ptr %_10.i.i.1.i, align 2, !alias.scope !44, !noalias !45, !noundef !24 
           48:  %rhs.i9.i.i.1.i = load i16, ptr %_11.i.i.1.i, align 2, !alias.scope !45, !noalias !44, !noundef !24 
           49:  %_5.i10.not.i.i.1.i = icmp eq i16 %lhs.i8.i.i.1.i, %rhs.i9.i.i.1.i 
           50:  br i1 %_5.i10.not.i.i.1.i, label %_ZN4core5slice3cmp13chaining_impl17h5a59d2cbaa8836d3E.exit, label %bb11.split.loop.exit15.i 
           51:  
           52: bb11.split.loop.exit13.i: ; preds = %bb1.i, %start 
           53:  %lhs.i.i.i.lcssa.i = phi i16 [ %lhs.i.i.i.i, %start ], [ %lhs.i.i.i.1.i, %bb1.i ] 
           54:  %rhs.i.i.i.lcssa.i = phi i16 [ %rhs.i.i.i.i, %start ], [ %rhs.i.i.i.1.i, %bb1.i ] 
           55:  %_6.i.i.i.le.i = icmp sle i16 %lhs.i.i.i.lcssa.i, %rhs.i.i.i.lcssa.i 
           56:  br label %_ZN4core5slice3cmp13chaining_impl17h5a59d2cbaa8836d3E.exit 
           57:  
           58: bb11.split.loop.exit15.i: ; preds = %bb6.i.i.i, %bb6.i.i.1.i 
           59:  %lhs.i8.i.i.lcssa.i = phi i16 [ %lhs.i8.i.i.i, %bb6.i.i.i ], [ %lhs.i8.i.i.1.i, %bb6.i.i.1.i ] 
           60:  %rhs.i9.i.i.lcssa.i = phi i16 [ %rhs.i9.i.i.i, %bb6.i.i.i ], [ %rhs.i9.i.i.1.i, %bb6.i.i.1.i ] 
           61:  %narrow.i.i.le.i = icmp ult i16 %lhs.i8.i.i.lcssa.i, %rhs.i9.i.i.lcssa.i 
           62:  br label %_ZN4core5slice3cmp13chaining_impl17h5a59d2cbaa8836d3E.exit 
           63:  
           64: bb6.i.i.i: ; preds = %start 
           65:  %_10.i.i.i = getelementptr inbounds nuw i8, ptr %a, i64 2 
           66:  %_11.i.i.i = getelementptr inbounds nuw i8, ptr %b, i64 2 
           67:  tail call void @llvm.experimental.noalias.scope.decl(metadata !46) 
           68:  tail call void @llvm.experimental.noalias.scope.decl(metadata !48) 
           69:  %lhs.i8.i.i.i = load i16, ptr %_10.i.i.i, align 2, !alias.scope !50, !noalias !51, !noundef !24 
           70:  %rhs.i9.i.i.i = load i16, ptr %_11.i.i.i, align 2, !alias.scope !51, !noalias !50, !noundef !24 
           71:  %_5.i10.not.i.i.i = icmp eq i16 %lhs.i8.i.i.i, %rhs.i9.i.i.i 
           72:  br i1 %_5.i10.not.i.i.i, label %bb1.i, label %bb11.split.loop.exit15.i 
check:51'0                                                                            X error: no match found
check:51'1                                                                              with "L10" equal to "bb1.i"
           73:  
check:51'0     ~
           74: _ZN4core5slice3cmp13chaining_impl17h5a59d2cbaa8836d3E.exit: ; preds = %bb6.i.i.1.i, %bb11.split.loop.exit13.i, %bb11.split.loop.exit15.i 
check:51'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
check:51'2                                                               ?                                                                               possible intended match
           75:  %_0.sroa.0.0.i = phi i1 [ %_6.i.i.i.le.i, %bb11.split.loop.exit13.i ], [ %narrow.i.i.le.i, %bb11.split.loop.exit15.i ], [ true, %bb6.i.i.1.i ] 
check:51'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
           76:  ret i1 %_0.sroa.0.0.i 
check:51'0     ~~~~~~~~~~~~~~~~~~~~~~~
           77: } 
check:51'0     ~~
           78:  
check:51'0     ~
           79: ; Function Attrs: nounwind uwtable 
check:51'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
           80: declare noundef range(i32 0, 10) i32 @rust_eh_personality(i32 noundef, i32 noundef, i64 noundef, ptr noundef, ptr noundef) unnamed_addr #2 
check:51'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
           81:  
check:51'0     ~
           82: ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(inaccessiblemem: readwrite) 
check:51'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
           83: declare void @llvm.experimental.noalias.scope.decl(metadata) #3 
check:51'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
           84:  
check:51'0     ~
           85: attributes #0 = { mustprogress nofree norecurse nosync nounwind willreturn memory(none) uwtable "frame-pointer"="non-leaf" "probe-stack"="inline-asm" "target-cpu"="apple-m1" } 
check:51'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
           86: attributes #1 = { mustprogress nofree norecurse nosync nounwind willreturn memory(argmem: read, inaccessiblemem: readwrite) uwtable "frame-pointer"="non-leaf" "probe-stack"="inline-asm" "target-cpu"="apple-m1" } 
check:51'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
           87: attributes #2 = { nounwind uwtable "frame-pointer"="non-leaf" "probe-stack"="inline-asm" "target-cpu"="apple-m1" } 
check:51'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
           88: attributes #3 = { nocallback nofree nosync nounwind willreturn memory(inaccessiblemem: readwrite) } 
check:51'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
           89:  
check:51'0     ~
           90: !llvm.module.flags = !{!0} 
check:51'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~
           91: !llvm.ident = !{!1} 
check:51'0     ~~~~~~~~~~~~~~~~~~~~
           92:  
check:51'0     ~
           93: !0 = !{i32 8, !"PIC Level", i32 2} 
check:51'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
           94: !1 = !{!"rustc version 1.91.0-nightly (953f71322 2025-08-19)"} 
check:51'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
           95: !2 = !{!3} 
check:51'0     ~~~~~~~~~~~
           96: !3 = distinct !{!3, !4, !"_ZN4core5slice3cmp13chaining_impl17h5a59d2cbaa8836d3E: %left.0"} 
check:51'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
           97: !4 = distinct !{!4, !"_ZN4core5slice3cmp13chaining_impl17h5a59d2cbaa8836d3E"} 
check:51'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
           98: !5 = !{!6} 
check:51'0     ~~~~~~~~~~~
           99: !6 = distinct !{!6, !4, !"_ZN4core5slice3cmp13chaining_impl17h5a59d2cbaa8836d3E: %right.0"} 
check:51'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
          100: !7 = !{!8} 
check:51'0     ~~~~~~~~~~~
          101: !8 = distinct !{!8, !9, !"_ZN4core3ops8function2Fn4call17h160d964305fd52caE: argument 0"} 
check:51'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
          102: !9 = distinct !{!9, !"_ZN4core3ops8function2Fn4call17h160d964305fd52caE"} 
check:51'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
          103: !10 = !{!11} 
check:51'0     ~~~~~~~~~~~~~
          104: !11 = distinct !{!11, !9, !"_ZN4core3ops8function2Fn4call17h160d964305fd52caE: argument 1"} 
check:51'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
          105: !12 = !{!13} 
check:51'0     ~~~~~~~~~~~~~
          106: !13 = distinct !{!13, !14, !"_ZN4core5tuple65_$LT$impl$u20$core..cmp..PartialOrd$u20$for$u20$$LP$U$C$T$RP$$GT$13__chaining_le17h94315e4246cb9b27E: %self"} 
check:51'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
          107: !14 = distinct !{!14, !"_ZN4core5tuple65_$LT$impl$u20$core..cmp..PartialOrd$u20$for$u20$$LP$U$C$T$RP$$GT$13__chaining_le17h94315e4246cb9b27E"} 
check:51'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
          108: !15 = !{!16} 
check:51'0     ~~~~~~~~~~~~~
          109: !16 = distinct !{!16, !14, !"_ZN4core5tuple65_$LT$impl$u20$core..cmp..PartialOrd$u20$for$u20$$LP$U$C$T$RP$$GT$13__chaining_le17h94315e4246cb9b27E: %other"} 
check:51'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
          110: !17 = !{!18} 
check:51'0     ~~~~~~~~~~~~~
          111: !18 = distinct !{!18, !19, !"_ZN4core3cmp5impls55_$LT$impl$u20$core..cmp..PartialOrd$u20$for$u20$i16$GT$13__chaining_le17h65bae47fe1a7cef3E: %self"} 
check:51'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
          112: !19 = distinct !{!19, !"_ZN4core3cmp5impls55_$LT$impl$u20$core..cmp..PartialOrd$u20$for$u20$i16$GT$13__chaining_le17h65bae47fe1a7cef3E"} 
check:51'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
          113: !20 = !{!21} 
check:51'0     ~~~~~~~~~~~~~
          114: !21 = distinct !{!21, !19, !"_ZN4core3cmp5impls55_$LT$impl$u20$core..cmp..PartialOrd$u20$for$u20$i16$GT$13__chaining_le17h65bae47fe1a7cef3E: %other"} 
check:51'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
          115: !22 = !{!18, !13, !8, !3} 
check:51'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~
          116: !23 = !{!21, !16, !11, !6} 
check:51'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~
          117: !24 = !{} 
check:51'0     ~~~~~~~~~~
          118: !25 = !{!26} 
check:51'0     ~~~~~~~~~~~~~
          119: !26 = distinct !{!26, !9, !"_ZN4core3ops8function2Fn4call17h160d964305fd52caE: argument 0:It1"} 
check:51'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
          120: !27 = !{!28} 
check:51'0     ~~~~~~~~~~~~~
          121: !28 = distinct !{!28, !9, !"_ZN4core3ops8function2Fn4call17h160d964305fd52caE: argument 1:It1"} 
check:51'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
          122: !29 = !{!30} 
check:51'0     ~~~~~~~~~~~~~
          123: !30 = distinct !{!30, !14, !"_ZN4core5tuple65_$LT$impl$u20$core..cmp..PartialOrd$u20$for$u20$$LP$U$C$T$RP$$GT$13__chaining_le17h94315e4246cb9b27E: %self:It1"} 
check:51'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
          124: !31 = !{!32} 
check:51'0     ~~~~~~~~~~~~~
          125: !32 = distinct !{!32, !14, !"_ZN4core5tuple65_$LT$impl$u20$core..cmp..PartialOrd$u20$for$u20$$LP$U$C$T$RP$$GT$13__chaining_le17h94315e4246cb9b27E: %other:It1"} 
check:51'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
          126: !33 = !{!34} 
check:51'0     ~~~~~~~~~~~~~
          127: !34 = distinct !{!34, !19, !"_ZN4core3cmp5impls55_$LT$impl$u20$core..cmp..PartialOrd$u20$for$u20$i16$GT$13__chaining_le17h65bae47fe1a7cef3E: %self:It1"} 
check:51'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
          128: !35 = !{!36} 
check:51'0     ~~~~~~~~~~~~~
          129: !36 = distinct !{!36, !19, !"_ZN4core3cmp5impls55_$LT$impl$u20$core..cmp..PartialOrd$u20$for$u20$i16$GT$13__chaining_le17h65bae47fe1a7cef3E: %other:It1"} 
check:51'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
          130: !37 = !{!34, !30, !26, !3} 
check:51'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~
          131: !38 = !{!36, !32, !28, !6} 
check:51'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~
          132: !39 = !{!40} 
check:51'0     ~~~~~~~~~~~~~
          133: !40 = distinct !{!40, !41, !"_ZN4core3cmp5impls55_$LT$impl$u20$core..cmp..PartialOrd$u20$for$u20$u16$GT$13__chaining_le17h8fe68ba1357aba2dE: %self:It1"} 
check:51'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
          134: !41 = distinct !{!41, !"_ZN4core3cmp5impls55_$LT$impl$u20$core..cmp..PartialOrd$u20$for$u20$u16$GT$13__chaining_le17h8fe68ba1357aba2dE"} 
check:51'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
          135: !42 = !{!43} 
check:51'0     ~~~~~~~~~~~~~
          136: !43 = distinct !{!43, !41, !"_ZN4core3cmp5impls55_$LT$impl$u20$core..cmp..PartialOrd$u20$for$u20$u16$GT$13__chaining_le17h8fe68ba1357aba2dE: %other:It1"} 
check:51'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
          137: !44 = !{!40, !30, !26, !3} 
check:51'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~
          138: !45 = !{!43, !32, !28, !6} 
check:51'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~
          139: !46 = !{!47} 
check:51'0     ~~~~~~~~~~~~~
          140: !47 = distinct !{!47, !41, !"_ZN4core3cmp5impls55_$LT$impl$u20$core..cmp..PartialOrd$u20$for$u20$u16$GT$13__chaining_le17h8fe68ba1357aba2dE: %self"} 
check:51'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
          141: !48 = !{!49} 
check:51'0     ~~~~~~~~~~~~~
          142: !49 = distinct !{!49, !41, !"_ZN4core3cmp5impls55_$LT$impl$u20$core..cmp..PartialOrd$u20$for$u20$u16$GT$13__chaining_le17h8fe68ba1357aba2dE: %other"} 
check:51'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
          143: !50 = !{!47, !13, !8, !3} 
check:51'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~
          144: !51 = !{!49, !16, !11, !6} 
check:51'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>>>>>
------------------------------------------

[bors]

💔 Test failed - checks-actions

[clarfonthey]

Appears to be a legitimate codegen failure related to Ord, but I'm not exactly sure why there'd be a regression here. Might just fix itself with a rebase.

[Randl]

Ok. It is a legitimate codegen failure; I can reproduce it locally, including after rebase. I do not understand what is specifically wrong with the codegen (cc @scottmcm ), but the reason appears to be this change:

https://github.com/rust-lang/rust/pull/144847/files#diff-b3bc3e9849f0b9690cf061db39e229a23495e0ff8dd3eded8e2ac5d9bb3eb7a7L215-R232

I'm unsure why the difference between the while loop and the for loop results in incorrect codegen. I can revert this specific change for now (it doesn't give us slice Ord anyway because that requires const closures, for example, in

rust/library/core/src/slice/cmp.rs

Line 186 in f70c98f

let len_chain = |a: &_, b: &_| ControlFlow::Break(usize::partial_cmp(a, b));

) until we either figure out how to make the while loop work with codegen, or we can use for in const code (though if I understand correctly, this will require iterators, which by themselves will probably depend on this code).

[bors]

☔ The latest upstream changes (presumably #145644) made this pull request unmergeable. Please resolve the merge conflicts.