Stop enabling in_band_lifetimes in rustc_data_structures
#91580
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There's a conversation in the tracking issue about possibly unaccepting `in_band_lifetimes`, but it's used heavily in the compiler, and thus there'd need to be a bunch of PRs like this if that were to happen. So here's one to see how much of an impact it has. (Oh, and I removed `nll` while I was here too, since it didn't seem needed. Let me know if I should put that back.)
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Thanks!
Yeah, in-band lifetimes were dogfooded at the time, like many other unstable features. @bors r+ |
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📌 Commit 308fd59 has been approved by |
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☀️ Test successful - checks-actions |
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Finished benchmarking commit (bc9326d): comparison url. Summary: This benchmark run did not return any relevant changes. If you disagree with this performance assessment, please file an issue in rust-lang/rustc-perf. @rustbot label: -perf-regression |
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…rochenkov Remove `in_band_lifetimes` from `rustc_mir_transform` Like rust-lang#91580, this was inspired by the conversation in rust-lang#44524 about possibly removing the feature from the compiler. This crate is a heavy `'tcx` user, so is a nice case study. r? `@petrochenkov` Three interesting ones: This one had the `'tcx` declared on the function, despite the trait taking a `'tcx`: ```diff -impl Visitor<'_> for UsedLocals { +impl<'tcx> Visitor<'tcx> for UsedLocals { fn visit_statement(&mut self, statement: &Statement<'tcx>, location: Location) { ``` This one use in-band for one, and underscore for the other: ```diff -pub fn remove_dead_blocks(tcx: TyCtxt<'tcx>, body: &mut Body<'_>) { +pub fn remove_dead_blocks<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) { ``` A spurious name, since there's no single-use-lifetime warning: ```diff -pub fn run_passes(tcx: TyCtxt<'tcx>, body: &'mir mut Body<'tcx>, passes: &[&dyn MirPass<'tcx>]) { +pub fn run_passes<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>, passes: &[&dyn MirPass<'tcx>]) { ```
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…rochenkov Remove `in_band_lifetimes` from `rustc_mir_transform` Like rust-lang#91580, this was inspired by the conversation in rust-lang#44524 about possibly removing the feature from the compiler. This crate is a heavy `'tcx` user, so is a nice case study. r? ``@petrochenkov`` Three interesting ones: This one had the `'tcx` declared on the function, despite the trait taking a `'tcx`: ```diff -impl Visitor<'_> for UsedLocals { +impl<'tcx> Visitor<'tcx> for UsedLocals { fn visit_statement(&mut self, statement: &Statement<'tcx>, location: Location) { ``` This one use in-band for one, and underscore for the other: ```diff -pub fn remove_dead_blocks(tcx: TyCtxt<'tcx>, body: &mut Body<'_>) { +pub fn remove_dead_blocks<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) { ``` A spurious name, since there's no single-use-lifetime warning: ```diff -pub fn run_passes(tcx: TyCtxt<'tcx>, body: &'mir mut Body<'tcx>, passes: &[&dyn MirPass<'tcx>]) { +pub fn run_passes<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>, passes: &[&dyn MirPass<'tcx>]) { ```
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There's a conversation started in the tracking issue about possibly unaccepting
in_band_lifetimes, but it's used heavily in the compiler, and thus there'd need to be a bunch of PRs like this if that were to happen.So here's one to see how much of an impact it has. For this crate, at least, it doesn't seem like in-band was a big win -- about half the places that were using it didn't even need a named lifetime.
(Oh, and I removed
nllwhile I was here too, since it didn't seem needed. Let me know if I should put that back.)r? @petrochenkov