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Commit b09e25e

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Simplify implementation for perf
1 parent 6179ddc commit b09e25e

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2 files changed

+27
-20
lines changed

2 files changed

+27
-20
lines changed

‎compiler/rustc_lint/src/redundant_lifetime_args.rs‎

Lines changed: 25 additions & 20 deletions
Original file line numberDiff line numberDiff line change
@@ -5,11 +5,10 @@ use rustc_data_structures::fx::FxHashSet;
55
use rustc_hir as hir;
66
use rustc_hir::def::DefKind;
77
use rustc_infer::infer::outlives::env::OutlivesEnvironment;
8-
use rustc_infer::infer::{SubregionOrigin,TyCtxtInferExt};
8+
use rustc_infer::infer::TyCtxtInferExt;
99
use rustc_macros::LintDiagnostic;
1010
use rustc_middle::ty::{self, TyCtxt};
1111
use rustc_session::lint::builtin::UNUSED_LIFETIMES;
12-
use rustc_span::DUMMY_SP;
1312
use rustc_trait_selection::traits::{outlives_bounds::InferCtxtExt, ObligationCtxt};
1413

1514
use crate::{LateContext, LateLintPass};
@@ -80,17 +79,6 @@ fn check<'tcx>(tcx: TyCtxt<'tcx>, param_env: ty::ParamEnv<'tcx>, owner_id: hir::
8079
| DefKind::Closure => return,
8180
}
8281

83-
let infcx = &tcx.infer_ctxt().build();
84-
let ocx = ObligationCtxt::new(infcx);
85-
86-
// Compute the implied outlives bounds for the item. This ensures that we treat
87-
// a signature with an argument like `&'a &'b ()` as implicitly having `'b: 'a`.
88-
let Ok(assumed_wf_types) = ocx.assumed_wf_types(param_env, owner_id.def_id) else {
89-
return;
90-
};
91-
let implied_bounds = infcx.implied_bounds_tys(param_env, owner_id.def_id, assumed_wf_types);
92-
let outlives_env = &OutlivesEnvironment::with_bounds(param_env, implied_bounds);
93-
9482
// The ordering of this lifetime map is a bit subtle.
9583
//
9684
// Specifically, we want to find a "candidate" lifetime that precedes a "victim" lifetime,
@@ -111,6 +99,22 @@ fn check<'tcx>(tcx: TyCtxt<'tcx>, param_env: ty::ParamEnv<'tcx>, owner_id: hir::
11199
}
112100
}
113101

102+
// No lifetimes except for `'static` to check.
103+
if lifetimes.len() == 1 {
104+
return;
105+
}
106+
107+
let infcx = &tcx.infer_ctxt().build();
108+
let ocx = ObligationCtxt::new(infcx);
109+
110+
// Compute the implied outlives bounds for the item. This ensures that we treat
111+
// a signature with an argument like `&'a &'b ()` as implicitly having `'b: 'a`.
112+
let Ok(assumed_wf_types) = ocx.assumed_wf_types(param_env, owner_id.def_id) else {
113+
return;
114+
};
115+
let implied_bounds = infcx.implied_bounds_tys(param_env, owner_id.def_id, assumed_wf_types);
116+
let outlives_env = &OutlivesEnvironment::with_bounds(param_env, implied_bounds);
117+
114118
// Keep track of lifetimes which have already been replaced with other lifetimes.
115119
// This makes sure that if `'a = 'b = 'c`, we don't say `'c` should be replaced by
116120
// both `'a` and `'b`.
@@ -128,6 +132,11 @@ fn check<'tcx>(tcx: TyCtxt<'tcx>, param_env: ty::ParamEnv<'tcx>, owner_id: hir::
128132
}
129133

130134
for &victim in &lifetimes[(idx + 1)..] {
135+
// We should not suggest renaming `'_` in `&'static &'_ str`.
136+
if !victim.has_name() {
137+
continue;
138+
}
139+
131140
// We only care about lifetimes that are "real", i.e. that have a def-id.
132141
let (ty::ReEarlyParam(ty::EarlyParamRegion { def_id, .. })
133142
| ty::ReLateParam(ty::LateParamRegion {
@@ -146,14 +155,10 @@ fn check<'tcx>(tcx: TyCtxt<'tcx>, param_env: ty::ParamEnv<'tcx>, owner_id: hir::
146155
continue;
147156
}
148157

149-
let infcx = infcx.fork();
150-
151-
// Require that `'candidate = 'victim`
152-
infcx.sub_regions(SubregionOrigin::RelateRegionParamBound(DUMMY_SP), candidate, victim);
153-
infcx.sub_regions(SubregionOrigin::RelateRegionParamBound(DUMMY_SP), victim, candidate);
154-
155158
// If there are no lifetime errors, then we have proven that `'candidate = 'victim`!
156-
if infcx.resolve_regions(outlives_env).is_empty() {
159+
if outlives_env.free_region_map().sub_free_regions(tcx, candidate, victim)
160+
&& outlives_env.free_region_map().sub_free_regions(tcx, victim, candidate)
161+
{
157162
shadowed.insert(victim);
158163
tcx.emit_spanned_lint(
159164
UNUSED_LIFETIMES,

‎tests/ui/regions/transitively-redundant-lifetimes.rs‎

Lines changed: 2 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -13,4 +13,6 @@ impl<'a> Bar<'a> {
1313
fn d<'b: 'a>(&'b self) {} //~ ERROR unnecessary lifetime parameter `'b`
1414
}
1515

16+
fn ok(x: &'static &()) {}
17+
1618
fn main() {}

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