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Remove Rvalue::Len again.#146564

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Sep 17, 2025
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Remove Rvalue::Len again.#146564
bors merged 3 commits intorust-lang:masterfrom
cjgillot:mir-nolen

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@cjgillot cjgillot commented Sep 14, 2025

Now that we have RawPtrKind::FakeForPtrMetadata, we can reimplement Rvalue::Len using PtrMetadata(&raw const (fake) place).

r? @scottmcm

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rustbot commented Sep 14, 2025

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

Some changes occurred in compiler/rustc_codegen_cranelift

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cc @WaffleLapkin

Some changes occurred in src/tools/clippy

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This PR changes MIR

cc @oli-obk, @RalfJung, @JakobDegen, @vakaras

Some changes occurred to MIR optimizations

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cc @RalfJung, @oli-obk, @lcnr

This PR changes rustc_public

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@rustbot rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-clippy Relevant to the Clippy team. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. T-libs Relevant to the library team, which will review and decide on the PR/issue. labels Sep 14, 2025
@cjgillot cjgillot force-pushed the mir-nolen branch 3 times, most recently from 3114e1b to 7613fdb Compare September 14, 2025 23:57
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scottmcm approved these changes Sep 16, 2025
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Thanks for picking this up!

Put a couple of thoughts for you to think about, but r=me even without them if you think they're not needed.

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tests/mir-opt/instsimplify/combine_array_len.rs Outdated
// EMIT_MIR combine_array_len.norm2.InstSimplify-after-simplifycfg.diff
fn norm2(x: [f32; 2]) -> f32 {
// CHECK-LABEL: fn norm2(
// CHECK-NOT: Len(
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I think this also needs CHECK-NOT: PtrMetadata or something? Since of course there's no Len now.

compiler/rustc_mir_build/src/builder/matches/test.rs
// actual = len(place)
self.cfg.push_assign(block, source_info, actual, Rvalue::Len(place));
let length_op = self.len_of_slice_or_array(block, place, test.span, source_info);
self.cfg.push_assign(block, source_info, actual, Rvalue::Use(length_op));
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Now that this can be _3 = 4_usize; instead of _3 = Len(_2);, should we have a MIR building test that shows that?

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rustbot commented Sep 16, 2025

This PR was rebased onto a different master commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

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scottmcm commented Sep 17, 2025

Thanks! Looks great.

@bors r+ rollup=iffy

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bors commented Sep 17, 2025

📌 Commit de73af9 has been approved by scottmcm

It is now in the queue for this repository.

@bors 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-review Status: Awaiting review from the assignee but also interested parties. labels Sep 17, 2025
Zalathar added a commit to Zalathar/rust that referenced this pull request Sep 17, 2025
@Zalathar
Rollup merge of rust-lang#146564 - cjgillot:mir-nolen, r=scottmcm
b67e165 
Remove Rvalue::Len again.

Now that we have `RawPtrKind::FakeForPtrMetadata`, we can reimplement `Rvalue::Len` using `PtrMetadata(&raw const (fake) place)`.

r? `@scottmcm`
This was referenced Sep 17, 2025
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bors added a commit that referenced this pull request Sep 17, 2025
@bors
Auto merge of #146666 - Zalathar:rollup-m2b8low, r=Zalathar
2ebb126 
Rollup of 14 pull requests

Successful merges:

 - #142807 (libtest: expose --fail-fast as an unstable command-line option)
 - #144871 (Stabilize `btree_entry_insert` feature)
 - #145071 (Update the minimum external LLVM to 20)
 - #145181 (remove FIXME block from `has_significant_drop`, it never encounters inference variables)
 - #145660 (initial implementation of the darwin_objc unstable feature)
 - #145838 (don't apply temporary lifetime extension rules to non-extended `super let`)
 - #146259 (Suggest removing Box::new instead of unboxing it)
 - #146410 (Iterator repeat: no infinite loop for `last` and `count`)
 - #146460 (Add tidy readme)
 - #146552 (StateTransform: Do not renumber resume local.)
 - #146564 (Remove Rvalue::Len again.)
 - #146581 (Detect attempt to use var-args in closure)
 - #146588 (tests/run-make: Update list of statically linked musl targets)
 - #146631 (cg_llvm: Replace some DIBuilder wrappers with LLVM-C API bindings (part 3))

r? `@ghost`
`@rustbot` modify labels: rollup
@bors bors merged commit 6473a0f into rust-lang:master Sep 17, 2025
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@rustbot rustbot added this to the 1.92.0 milestone Sep 17, 2025
rust-timer added a commit that referenced this pull request Sep 17, 2025
@rust-timer
Unrolled build for #146564
cd9fb54 
Rollup merge of #146564 - cjgillot:mir-nolen, r=scottmcm

Remove Rvalue::Len again.

Now that we have `RawPtrKind::FakeForPtrMetadata`, we can reimplement `Rvalue::Len` using `PtrMetadata(&raw const (fake) place)`.

r? ``@scottmcm``
@cjgillot cjgillot deleted the mir-nolen branch September 17, 2025 10:50
@IntegralPilot IntegralPilot mentioned this pull request Sep 18, 2025
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tautschnig added a commit to tautschnig/kani that referenced this pull request Sep 18, 2025
@tautschnig
Upgrade Rust toolchain to 2025-09-18
00415f9 
Relevant upstream PR:
- rust-lang/rust#146564 (Remove Rvalue::Len again.)

Resolves: model-checking#4365
@tautschnig tautschnig mentioned this pull request Sep 18, 2025
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@github-actions github-actions bot mentioned this pull request Sep 18, 2025
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github-merge-queue bot pushed a commit to model-checking/kani that referenced this pull request Sep 18, 2025
@tautschnig
Upgrade Rust toolchain to 2025-09-18 (#4366)
bfb22f1 
Relevant upstream PR:
- rust-lang/rust#146564 (Remove Rvalue::Len
again.)

Resolves: #4365

By submitting this pull request, I confirm that my contribution is made
under the terms of the Apache 2.0 and MIT licenses.
github-actions bot pushed a commit to rust-lang/rustc-dev-guide that referenced this pull request Sep 22, 2025
@bors
Auto merge of #146666 - Zalathar:rollup-m2b8low, r=Zalathar
f81ad3e 
Rollup of 14 pull requests

Successful merges:

 - rust-lang/rust#142807 (libtest: expose --fail-fast as an unstable command-line option)
 - rust-lang/rust#144871 (Stabilize `btree_entry_insert` feature)
 - rust-lang/rust#145071 (Update the minimum external LLVM to 20)
 - rust-lang/rust#145181 (remove FIXME block from `has_significant_drop`, it never encounters inference variables)
 - rust-lang/rust#145660 (initial implementation of the darwin_objc unstable feature)
 - rust-lang/rust#145838 (don't apply temporary lifetime extension rules to non-extended `super let`)
 - rust-lang/rust#146259 (Suggest removing Box::new instead of unboxing it)
 - rust-lang/rust#146410 (Iterator repeat: no infinite loop for `last` and `count`)
 - rust-lang/rust#146460 (Add tidy readme)
 - rust-lang/rust#146552 (StateTransform: Do not renumber resume local.)
 - rust-lang/rust#146564 (Remove Rvalue::Len again.)
 - rust-lang/rust#146581 (Detect attempt to use var-args in closure)
 - rust-lang/rust#146588 (tests/run-make: Update list of statically linked musl targets)
 - rust-lang/rust#146631 (cg_llvm: Replace some DIBuilder wrappers with LLVM-C API bindings (part 3))

r? `@ghost`
`@rustbot` modify labels: rollup
@Lysxia Lysxia mentioned this pull request Oct 1, 2025
Merged
github-actions bot pushed a commit to model-checking/verify-rust-std that referenced this pull request Oct 9, 2025
@Zalathar
Rollup merge of rust-lang#146564 - cjgillot:mir-nolen, r=scottmcm
d47b3de 
Remove Rvalue::Len again.

Now that we have `RawPtrKind::FakeForPtrMetadata`, we can reimplement `Rvalue::Len` using `PtrMetadata(&raw const (fake) place)`.

r? ``@scottmcm``
rust-cloud-vms bot pushed a commit to makai410/rustc_public that referenced this pull request Oct 12, 2025
@bors
Auto merge of #146666 - Zalathar:rollup-m2b8low, r=Zalathar
e7a9666 
Rollup of 14 pull requests

Successful merges:

 - rust-lang/rust#142807 (libtest: expose --fail-fast as an unstable command-line option)
 - rust-lang/rust#144871 (Stabilize `btree_entry_insert` feature)
 - rust-lang/rust#145071 (Update the minimum external LLVM to 20)
 - rust-lang/rust#145181 (remove FIXME block from `has_significant_drop`, it never encounters inference variables)
 - rust-lang/rust#145660 (initial implementation of the darwin_objc unstable feature)
 - rust-lang/rust#145838 (don't apply temporary lifetime extension rules to non-extended `super let`)
 - rust-lang/rust#146259 (Suggest removing Box::new instead of unboxing it)
 - rust-lang/rust#146410 (Iterator repeat: no infinite loop for `last` and `count`)
 - rust-lang/rust#146460 (Add tidy readme)
 - rust-lang/rust#146552 (StateTransform: Do not renumber resume local.)
 - rust-lang/rust#146564 (Remove Rvalue::Len again.)
 - rust-lang/rust#146581 (Detect attempt to use var-args in closure)
 - rust-lang/rust#146588 (tests/run-make: Update list of statically linked musl targets)
 - rust-lang/rust#146631 (cg_llvm: Replace some DIBuilder wrappers with LLVM-C API bindings (part 3))

r? `@ghost`
`@rustbot` modify labels: rollup
makai410 pushed a commit to makai410/rust that referenced this pull request Nov 8, 2025
@Zalathar
Rollup merge of rust-lang#146564 - cjgillot:mir-nolen, r=scottmcm
334da86 
Remove Rvalue::Len again.

Now that we have `RawPtrKind::FakeForPtrMetadata`, we can reimplement `Rvalue::Len` using `PtrMetadata(&raw const (fake) place)`.

r? ``@scottmcm``
makai410 pushed a commit to makai410/rust that referenced this pull request Nov 8, 2025
@bors
Auto merge of rust-lang#146666 - Zalathar:rollup-m2b8low, r=Zalathar
4ade8dc 
Rollup of 14 pull requests

Successful merges:

 - rust-lang#142807 (libtest: expose --fail-fast as an unstable command-line option)
 - rust-lang#144871 (Stabilize `btree_entry_insert` feature)
 - rust-lang#145071 (Update the minimum external LLVM to 20)
 - rust-lang#145181 (remove FIXME block from `has_significant_drop`, it never encounters inference variables)
 - rust-lang#145660 (initial implementation of the darwin_objc unstable feature)
 - rust-lang#145838 (don't apply temporary lifetime extension rules to non-extended `super let`)
 - rust-lang#146259 (Suggest removing Box::new instead of unboxing it)
 - rust-lang#146410 (Iterator repeat: no infinite loop for `last` and `count`)
 - rust-lang#146460 (Add tidy readme)
 - rust-lang#146552 (StateTransform: Do not renumber resume local.)
 - rust-lang#146564 (Remove Rvalue::Len again.)
 - rust-lang#146581 (Detect attempt to use var-args in closure)
 - rust-lang#146588 (tests/run-make: Update list of statically linked musl targets)
 - rust-lang#146631 (cg_llvm: Replace some DIBuilder wrappers with LLVM-C API bindings (part 3))

r? `@ghost`
`@rustbot` modify labels: rollup
makai410 pushed a commit to makai410/rust that referenced this pull request Nov 10, 2025
@Zalathar
Rollup merge of rust-lang#146564 - cjgillot:mir-nolen, r=scottmcm
978988f 
Remove Rvalue::Len again.

Now that we have `RawPtrKind::FakeForPtrMetadata`, we can reimplement `Rvalue::Len` using `PtrMetadata(&raw const (fake) place)`.

r? ``@scottmcm``
makai410 pushed a commit to makai410/rust that referenced this pull request Nov 10, 2025
@bors
Auto merge of rust-lang#146666 - Zalathar:rollup-m2b8low, r=Zalathar
88ceeff 
Rollup of 14 pull requests

Successful merges:

 - rust-lang#142807 (libtest: expose --fail-fast as an unstable command-line option)
 - rust-lang#144871 (Stabilize `btree_entry_insert` feature)
 - rust-lang#145071 (Update the minimum external LLVM to 20)
 - rust-lang#145181 (remove FIXME block from `has_significant_drop`, it never encounters inference variables)
 - rust-lang#145660 (initial implementation of the darwin_objc unstable feature)
 - rust-lang#145838 (don't apply temporary lifetime extension rules to non-extended `super let`)
 - rust-lang#146259 (Suggest removing Box::new instead of unboxing it)
 - rust-lang#146410 (Iterator repeat: no infinite loop for `last` and `count`)
 - rust-lang#146460 (Add tidy readme)
 - rust-lang#146552 (StateTransform: Do not renumber resume local.)
 - rust-lang#146564 (Remove Rvalue::Len again.)
 - rust-lang#146581 (Detect attempt to use var-args in closure)
 - rust-lang#146588 (tests/run-make: Update list of statically linked musl targets)
 - rust-lang#146631 (cg_llvm: Replace some DIBuilder wrappers with LLVM-C API bindings (part 3))

r? `@ghost`
`@rustbot` modify labels: rollup
makai410 pushed a commit to makai410/rustc_public that referenced this pull request Nov 16, 2025
@bors
Auto merge of #146666 - Zalathar:rollup-m2b8low, r=Zalathar
d84b315 
Rollup of 14 pull requests

Successful merges:

 - rust-lang/rust#142807 (libtest: expose --fail-fast as an unstable command-line option)
 - rust-lang/rust#144871 (Stabilize `btree_entry_insert` feature)
 - rust-lang/rust#145071 (Update the minimum external LLVM to 20)
 - rust-lang/rust#145181 (remove FIXME block from `has_significant_drop`, it never encounters inference variables)
 - rust-lang/rust#145660 (initial implementation of the darwin_objc unstable feature)
 - rust-lang/rust#145838 (don't apply temporary lifetime extension rules to non-extended `super let`)
 - rust-lang/rust#146259 (Suggest removing Box::new instead of unboxing it)
 - rust-lang/rust#146410 (Iterator repeat: no infinite loop for `last` and `count`)
 - rust-lang/rust#146460 (Add tidy readme)
 - rust-lang/rust#146552 (StateTransform: Do not renumber resume local.)
 - rust-lang/rust#146564 (Remove Rvalue::Len again.)
 - rust-lang/rust#146581 (Detect attempt to use var-args in closure)
 - rust-lang/rust#146588 (tests/run-make: Update list of statically linked musl targets)
 - rust-lang/rust#146631 (cg_llvm: Replace some DIBuilder wrappers with LLVM-C API bindings (part 3))

r? `@ghost`
`@rustbot` modify labels: rollup
Kobzol pushed a commit to Kobzol/rustc_codegen_cranelift that referenced this pull request Dec 29, 2025
@bors
Auto merge of #146666 - Zalathar:rollup-m2b8low, r=Zalathar
ef96105 
Rollup of 14 pull requests

Successful merges:

 - rust-lang/rust#142807 (libtest: expose --fail-fast as an unstable command-line option)
 - rust-lang/rust#144871 (Stabilize `btree_entry_insert` feature)
 - rust-lang/rust#145071 (Update the minimum external LLVM to 20)
 - rust-lang/rust#145181 (remove FIXME block from `has_significant_drop`, it never encounters inference variables)
 - rust-lang/rust#145660 (initial implementation of the darwin_objc unstable feature)
 - rust-lang/rust#145838 (don't apply temporary lifetime extension rules to non-extended `super let`)
 - rust-lang/rust#146259 (Suggest removing Box::new instead of unboxing it)
 - rust-lang/rust#146410 (Iterator repeat: no infinite loop for `last` and `count`)
 - rust-lang/rust#146460 (Add tidy readme)
 - rust-lang/rust#146552 (StateTransform: Do not renumber resume local.)
 - rust-lang/rust#146564 (Remove Rvalue::Len again.)
 - rust-lang/rust#146581 (Detect attempt to use var-args in closure)
 - rust-lang/rust#146588 (tests/run-make: Update list of statically linked musl targets)
 - rust-lang/rust#146631 (cg_llvm: Replace some DIBuilder wrappers with LLVM-C API bindings (part 3))

r? `@ghost`
`@rustbot` modify labels: rollup
christian-schilling pushed a commit to christian-schilling/rustc_codegen_cranelift that referenced this pull request Jan 27, 2026
@bors
Auto merge of #146666 - Zalathar:rollup-m2b8low, r=Zalathar
d613def 
Rollup of 14 pull requests

Successful merges:

 - rust-lang/rust#142807 (libtest: expose --fail-fast as an unstable command-line option)
 - rust-lang/rust#144871 (Stabilize `btree_entry_insert` feature)
 - rust-lang/rust#145071 (Update the minimum external LLVM to 20)
 - rust-lang/rust#145181 (remove FIXME block from `has_significant_drop`, it never encounters inference variables)
 - rust-lang/rust#145660 (initial implementation of the darwin_objc unstable feature)
 - rust-lang/rust#145838 (don't apply temporary lifetime extension rules to non-extended `super let`)
 - rust-lang/rust#146259 (Suggest removing Box::new instead of unboxing it)
 - rust-lang/rust#146410 (Iterator repeat: no infinite loop for `last` and `count`)
 - rust-lang/rust#146460 (Add tidy readme)
 - rust-lang/rust#146552 (StateTransform: Do not renumber resume local.)
 - rust-lang/rust#146564 (Remove Rvalue::Len again.)
 - rust-lang/rust#146581 (Detect attempt to use var-args in closure)
 - rust-lang/rust#146588 (tests/run-make: Update list of statically linked musl targets)
 - rust-lang/rust#146631 (cg_llvm: Replace some DIBuilder wrappers with LLVM-C API bindings (part 3))

r? `@ghost`
`@rustbot` modify labels: rollup
christian-schilling pushed a commit to christian-schilling/rustc_codegen_cranelift that referenced this pull request Jan 27, 2026
@bors
Auto merge of #146666 - Zalathar:rollup-m2b8low, r=Zalathar
e4ff631 
Rollup of 14 pull requests

Successful merges:

 - rust-lang/rust#142807 (libtest: expose --fail-fast as an unstable command-line option)
 - rust-lang/rust#144871 (Stabilize `btree_entry_insert` feature)
 - rust-lang/rust#145071 (Update the minimum external LLVM to 20)
 - rust-lang/rust#145181 (remove FIXME block from `has_significant_drop`, it never encounters inference variables)
 - rust-lang/rust#145660 (initial implementation of the darwin_objc unstable feature)
 - rust-lang/rust#145838 (don't apply temporary lifetime extension rules to non-extended `super let`)
 - rust-lang/rust#146259 (Suggest removing Box::new instead of unboxing it)
 - rust-lang/rust#146410 (Iterator repeat: no infinite loop for `last` and `count`)
 - rust-lang/rust#146460 (Add tidy readme)
 - rust-lang/rust#146552 (StateTransform: Do not renumber resume local.)
 - rust-lang/rust#146564 (Remove Rvalue::Len again.)
 - rust-lang/rust#146581 (Detect attempt to use var-args in closure)
 - rust-lang/rust#146588 (tests/run-make: Update list of statically linked musl targets)
 - rust-lang/rust#146631 (cg_llvm: Replace some DIBuilder wrappers with LLVM-C API bindings (part 3))

r? `@ghost`
`@rustbot` modify labels: rollup
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