Skip to content

Conversation

compiler-errors
Copy link
Member

@compiler-errors compiler-errors commented Jul 6, 2025

Instance::try_resolve on a default trait body method will always fail, since it's still possible to further substitute. This leads to a cycle, since in tests/mir-opt/inline_default_trait_body.rs, both Trait::a and Trait::b need to consider the other to be cyclical, but since we couldn't resolve a body, we'd just consider nothing to be cyclical.

The root instance we care about when computing mir_callgraph_cyclic is trivial to compute (it's just InstanceKind::Item), so just replace it with a call to Instance::new_raw.

r? @cjgillot @oli-obk

Fixes #143534

@rustbot rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Jul 6, 2025
@rustbot
Copy link
Collaborator

rustbot commented Jul 6, 2025

Some changes occurred to MIR optimizations

cc @rust-lang/wg-mir-opt

@cjgillot
Copy link
Contributor

cjgillot commented Jul 7, 2025

Thanks for fixing this!
@bors r+

@bors
Copy link
Collaborator

bors commented Jul 7, 2025

📌 Commit a40274d has been approved by cjgillot

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 Jul 7, 2025
bors added a commit that referenced this pull request Jul 7, 2025
Rollup of 11 pull requests

Successful merges:

 - #143130 (doc(std): clarify `NonZero<T>` usage limitation in doc comment)
 - #143415 (Get rid of build-powerpc64le-toolchain.sh)
 - #143464 (Make tests/ui/abi/debug.rs cross-compile)
 - #143482 (Fix short linker error output)
 - #143524 (Move `stable_mir` back to its own crate)
 - #143528 (interpret: rename StackPopCleanup)
 - #143551 (Dont resolve instance of root in `mir_callgraph_cyclic`)
 - #143558 (mbe: Refactors and function extractions in `compile_declarative_macro`)
 - #143563 (std: fix typo in `std::path`)
 - #143564 (compiler: Deduplicate `must_emit_unwind_tables()` comments)
 - #143577 (Disable download-rustc for library profile)

r? `@ghost`
`@rustbot` modify labels: rollup
@bors bors merged commit b6015a6 into rust-lang:master Jul 7, 2025
11 checks passed
@rustbot rustbot added this to the 1.90.0 milestone Jul 7, 2025
rust-timer added a commit that referenced this pull request Jul 7, 2025
Rollup merge of #143551 - compiler-errors:root-sub, r=cjgillot

Dont resolve instance of root in `mir_callgraph_cyclic`

`Instance::try_resolve` on a default trait body method will always fail, since it's still possible to further substitute. This leads to a cycle, since in `tests/mir-opt/inline_default_trait_body.rs`, both `Trait::a` and `Trait::b` need to consider the other to be cyclical, but since we couldn't resolve a body, we'd just consider *nothing* to be cyclical.

The root instance we care about when computing `mir_callgraph_cyclic` is trivial to compute (it's just `InstanceKind::Item`), so just replace it with a call to `Instance::new_raw`.

r? `@cjgillot` `@oli-obk`

Fixes #143534
github-actions bot pushed a commit to devnexen/miri that referenced this pull request Jul 8, 2025
Rollup of 11 pull requests

Successful merges:

 - rust-lang/rust#143130 (doc(std): clarify `NonZero<T>` usage limitation in doc comment)
 - rust-lang/rust#143415 (Get rid of build-powerpc64le-toolchain.sh)
 - rust-lang/rust#143464 (Make tests/ui/abi/debug.rs cross-compile)
 - rust-lang/rust#143482 (Fix short linker error output)
 - rust-lang/rust#143524 (Move `stable_mir` back to its own crate)
 - rust-lang/rust#143528 (interpret: rename StackPopCleanup)
 - rust-lang/rust#143551 (Dont resolve instance of root in `mir_callgraph_cyclic`)
 - rust-lang/rust#143558 (mbe: Refactors and function extractions in `compile_declarative_macro`)
 - rust-lang/rust#143563 (std: fix typo in `std::path`)
 - rust-lang/rust#143564 (compiler: Deduplicate `must_emit_unwind_tables()` comments)
 - rust-lang/rust#143577 (Disable download-rustc for library profile)

r? `@ghost`
`@rustbot` modify labels: rollup
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Labels
S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue.
Projects
None yet
Development

Successfully merging this pull request may close these issues.

cycle detected when optimizing MIR
4 participants