diff --git a/compiler/rustc_errors/src/diagnostic_impls.rs b/compiler/rustc_errors/src/diagnostic_impls.rs index f90190797ae..6c0551848d6 100644 --- a/compiler/rustc_errors/src/diagnostic_impls.rs +++ b/compiler/rustc_errors/src/diagnostic_impls.rs @@ -46,6 +46,7 @@ impl<'a, T: Clone + IntoDiagArg> IntoDiagArg for &'a T { } } +#[macro_export] macro_rules! into_diag_arg_using_display { ($( $ty:ty ),+ $(,)?) => { $( diff --git a/compiler/rustc_hir_analysis/messages.ftl b/compiler/rustc_hir_analysis/messages.ftl index e66a834ab9e..86b8b6d6b2b 100644 --- a/compiler/rustc_hir_analysis/messages.ftl +++ b/compiler/rustc_hir_analysis/messages.ftl @@ -355,6 +355,9 @@ hir_analysis_pattern_type_wild_pat = "wildcard patterns are not permitted for pa hir_analysis_placeholder_not_allowed_item_signatures = the placeholder `_` is not allowed within types on item signatures for {$kind} .label = not allowed in type signatures +hir_analysis_redundant_lifetime_args = unnecessary lifetime parameter `{$victim}` + .note = you can use the `{$candidate}` lifetime directly, in place of `{$victim}` + hir_analysis_requires_note = the `{$trait_name}` impl for `{$ty}` requires that `{$error_predicate}` hir_analysis_return_type_notation_equality_bound = diff --git a/compiler/rustc_hir_analysis/src/check/wfcheck.rs b/compiler/rustc_hir_analysis/src/check/wfcheck.rs index 4fd7c870fc7..c26f982fa47 100644 --- a/compiler/rustc_hir_analysis/src/check/wfcheck.rs +++ b/compiler/rustc_hir_analysis/src/check/wfcheck.rs @@ -8,11 +8,13 @@ use rustc_ast as ast; use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexSet}; use rustc_errors::{codes::*, pluralize, struct_span_code_err, Applicability, ErrorGuaranteed}; use rustc_hir as hir; +use rustc_hir::def::DefKind; use rustc_hir::def_id::{DefId, LocalDefId, LocalModDefId}; use rustc_hir::lang_items::LangItem; use rustc_hir::ItemKind; use rustc_infer::infer::outlives::env::OutlivesEnvironment; use rustc_infer::infer::{self, InferCtxt, TyCtxtInferExt}; +use rustc_macros::LintDiagnostic; use rustc_middle::query::Providers; use rustc_middle::ty::print::with_no_trimmed_paths; use rustc_middle::ty::trait_def::TraitSpecializationKind; @@ -136,6 +138,8 @@ where infcx.implied_bounds_tys_compat(param_env, body_def_id, &assumed_wf_types, false); let outlives_env = OutlivesEnvironment::with_bounds(param_env, implied_bounds); + lint_redundant_lifetimes(tcx, body_def_id, &outlives_env); + let errors = infcx.resolve_regions(&outlives_env); if errors.is_empty() { return Ok(()); @@ -2010,6 +2014,137 @@ fn check_mod_type_wf(tcx: TyCtxt<'_>, module: LocalModDefId) -> Result<(), Error res } +fn lint_redundant_lifetimes<'tcx>( + tcx: TyCtxt<'tcx>, + owner_id: LocalDefId, + outlives_env: &OutlivesEnvironment<'tcx>, +) { + let def_kind = tcx.def_kind(owner_id); + match def_kind { + DefKind::Struct + | DefKind::Union + | DefKind::Enum + | DefKind::Trait + | DefKind::TraitAlias + | DefKind::Fn + | DefKind::Const + | DefKind::Impl { of_trait: _ } => { + // Proceed + } + DefKind::AssocFn | DefKind::AssocTy | DefKind::AssocConst => { + let parent_def_id = tcx.local_parent(owner_id); + if matches!(tcx.def_kind(parent_def_id), DefKind::Impl { of_trait: true }) { + // Don't check for redundant lifetimes for associated items of trait + // implementations, since the signature is required to be compatible + // with the trait, even if the implementation implies some lifetimes + // are redundant. + return; + } + } + DefKind::Mod + | DefKind::Variant + | DefKind::TyAlias + | DefKind::ForeignTy + | DefKind::TyParam + | DefKind::ConstParam + | DefKind::Static { .. } + | DefKind::Ctor(_, _) + | DefKind::Macro(_) + | DefKind::ExternCrate + | DefKind::Use + | DefKind::ForeignMod + | DefKind::AnonConst + | DefKind::InlineConst + | DefKind::OpaqueTy + | DefKind::Field + | DefKind::LifetimeParam + | DefKind::GlobalAsm + | DefKind::Closure => return, + } + + // The ordering of this lifetime map is a bit subtle. + // + // Specifically, we want to find a "candidate" lifetime that precedes a "victim" lifetime, + // where we can prove that `'candidate = 'victim`. + // + // `'static` must come first in this list because we can never replace `'static` with + // something else, but if we find some lifetime `'a` where `'a = 'static`, we want to + // suggest replacing `'a` with `'static`. + let mut lifetimes = vec![tcx.lifetimes.re_static]; + lifetimes.extend( + ty::GenericArgs::identity_for_item(tcx, owner_id).iter().filter_map(|arg| arg.as_region()), + ); + // If we are in a function, add its late-bound lifetimes too. + if matches!(def_kind, DefKind::Fn | DefKind::AssocFn) { + for var in tcx.fn_sig(owner_id).instantiate_identity().bound_vars() { + let ty::BoundVariableKind::Region(kind) = var else { continue }; + lifetimes.push(ty::Region::new_late_param(tcx, owner_id.to_def_id(), kind)); + } + } + lifetimes.retain(|candidate| candidate.has_name()); + + // Keep track of lifetimes which have already been replaced with other lifetimes. + // This makes sure that if `'a = 'b = 'c`, we don't say `'c` should be replaced by + // both `'a` and `'b`. + let mut shadowed = FxHashSet::default(); + + for (idx, &candidate) in lifetimes.iter().enumerate() { + // Don't suggest removing a lifetime twice. We only need to check this + // here and not up in the `victim` loop because equality is transitive, + // so if A = C and B = C, then A must = B, so it'll be shadowed too in + // A's victim loop. + if shadowed.contains(&candidate) { + continue; + } + + for &victim in &lifetimes[(idx + 1)..] { + // We should only have late-bound lifetimes of the `BrNamed` variety, + // since we get these signatures straight from `hir_lowering`. And any + // other regions (ReError/ReStatic/etc.) shouldn't matter, since we + // can't really suggest to remove them. + let (ty::ReEarlyParam(ty::EarlyParamRegion { def_id, .. }) + | ty::ReLateParam(ty::LateParamRegion { + bound_region: ty::BoundRegionKind::BrNamed(def_id, _), + .. + })) = victim.kind() + else { + continue; + }; + + // Do not rename lifetimes not local to this item since they'll overlap + // with the lint running on the parent. We still want to consider parent + // lifetimes which make child lifetimes redundant, otherwise we would + // have truncated the `identity_for_item` args above. + if tcx.parent(def_id) != owner_id.to_def_id() { + continue; + } + + // If `candidate <: victim` and `victim <: candidate`, then they're equal. + if outlives_env.free_region_map().sub_free_regions(tcx, candidate, victim) + && outlives_env.free_region_map().sub_free_regions(tcx, victim, candidate) + { + shadowed.insert(victim); + tcx.emit_node_span_lint( + rustc_lint_defs::builtin::REDUNDANT_LIFETIMES, + tcx.local_def_id_to_hir_id(def_id.expect_local()), + tcx.def_span(def_id), + RedundantLifetimeArgsLint { candidate, victim }, + ); + } + } + } +} + +#[derive(LintDiagnostic)] +#[diag(hir_analysis_redundant_lifetime_args)] +#[note] +struct RedundantLifetimeArgsLint<'tcx> { + /// The lifetime we have found to be redundant. + victim: ty::Region<'tcx>, + // The lifetime we can replace the victim with. + candidate: ty::Region<'tcx>, +} + pub fn provide(providers: &mut Providers) { *providers = Providers { check_mod_type_wf, check_well_formed, ..*providers }; } diff --git a/compiler/rustc_hir_analysis/src/collect/resolve_bound_vars.rs b/compiler/rustc_hir_analysis/src/collect/resolve_bound_vars.rs index 0b8ac9926e4..affd678fc6c 100644 --- a/compiler/rustc_hir_analysis/src/collect/resolve_bound_vars.rs +++ b/compiler/rustc_hir_analysis/src/collect/resolve_bound_vars.rs @@ -20,7 +20,6 @@ use rustc_middle::hir::nested_filter; use rustc_middle::middle::resolve_bound_vars::*; use rustc_middle::query::Providers; use rustc_middle::ty::{self, TyCtxt, TypeSuperVisitable, TypeVisitor}; -use rustc_session::lint; use rustc_span::def_id::DefId; use rustc_span::symbol::{sym, Ident}; use rustc_span::Span; @@ -867,31 +866,6 @@ impl<'a, 'tcx> Visitor<'tcx> for BoundVarContext<'a, 'tcx> { }) => { self.visit_lifetime(lifetime); walk_list!(self, visit_param_bound, bounds); - - if lifetime.res != hir::LifetimeName::Static { - for bound in bounds { - let hir::GenericBound::Outlives(lt) = bound else { - continue; - }; - if lt.res != hir::LifetimeName::Static { - continue; - } - self.insert_lifetime(lt, ResolvedArg::StaticLifetime); - self.tcx.node_span_lint( - lint::builtin::UNUSED_LIFETIMES, - lifetime.hir_id, - lifetime.ident.span, - format!("unnecessary lifetime parameter `{}`", lifetime.ident), - |lint| { - let help = format!( - "you can use the `'static` lifetime directly, in place of `{}`", - lifetime.ident, - ); - lint.help(help); - }, - ); - } - } } &hir::WherePredicate::EqPredicate(hir::WhereEqPredicate { lhs_ty, rhs_ty, .. }) => { self.visit_ty(lhs_ty); diff --git a/compiler/rustc_lint_defs/src/builtin.rs b/compiler/rustc_lint_defs/src/builtin.rs index 53b5273803c..2713690f812 100644 --- a/compiler/rustc_lint_defs/src/builtin.rs +++ b/compiler/rustc_lint_defs/src/builtin.rs @@ -79,6 +79,7 @@ declare_lint_pass! { PROC_MACRO_BACK_COMPAT, PROC_MACRO_DERIVE_RESOLUTION_FALLBACK, PUB_USE_OF_PRIVATE_EXTERN_CRATE, + REDUNDANT_LIFETIMES, REFINING_IMPL_TRAIT_INTERNAL, REFINING_IMPL_TRAIT_REACHABLE, RENAMED_AND_REMOVED_LINTS, @@ -1707,6 +1708,33 @@ declare_lint! { "detects lifetime parameters that are never used" } +declare_lint! { + /// The `redundant_lifetimes` lint detects lifetime parameters that are + /// redundant because they are equal to another named lifetime. + /// + /// ### Example + /// + /// ```rust,compile_fail + /// #[deny(redundant_lifetimes)] + /// + /// // `'a = 'static`, so all usages of `'a` can be replaced with `'static` + /// pub fn bar<'a: 'static>() {} + /// + /// // `'a = 'b`, so all usages of `'b` can be replaced with `'a` + /// pub fn bar<'a: 'b, 'b: 'a>() {} + /// ``` + /// + /// {{produces}} + /// + /// ### Explanation + /// + /// Unused lifetime parameters may signal a mistake or unfinished code. + /// Consider removing the parameter. + pub REDUNDANT_LIFETIMES, + Allow, + "detects lifetime parameters that are redundant because they are equal to some other named lifetime" +} + declare_lint! { /// The `tyvar_behind_raw_pointer` lint detects raw pointer to an /// inference variable. diff --git a/compiler/rustc_middle/src/ty/context.rs b/compiler/rustc_middle/src/ty/context.rs index 0daf83162db..6275c5d2a11 100644 --- a/compiler/rustc_middle/src/ty/context.rs +++ b/compiler/rustc_middle/src/ty/context.rs @@ -757,7 +757,7 @@ pub struct GlobalCtxt<'tcx> { impl<'tcx> GlobalCtxt<'tcx> { /// Installs `self` in a `TyCtxt` and `ImplicitCtxt` for the duration of /// `f`. - pub fn enter<'a: 'tcx, F, R>(&'a self, f: F) -> R + pub fn enter(&'tcx self, f: F) -> R where F: FnOnce(TyCtxt<'tcx>) -> R, { diff --git a/compiler/rustc_middle/src/ty/diagnostics.rs b/compiler/rustc_middle/src/ty/diagnostics.rs index ee18647cdd8..cc1d6e50f6d 100644 --- a/compiler/rustc_middle/src/ty/diagnostics.rs +++ b/compiler/rustc_middle/src/ty/diagnostics.rs @@ -5,13 +5,13 @@ use std::fmt::Write; use std::ops::ControlFlow; use crate::ty::{ - AliasTy, Const, ConstKind, FallibleTypeFolder, InferConst, InferTy, Opaque, PolyTraitPredicate, - Projection, Ty, TyCtxt, TypeFoldable, TypeSuperFoldable, TypeSuperVisitable, TypeVisitable, - TypeVisitor, + self, AliasTy, Const, ConstKind, FallibleTypeFolder, InferConst, InferTy, Opaque, + PolyTraitPredicate, Projection, Ty, TyCtxt, TypeFoldable, TypeSuperFoldable, + TypeSuperVisitable, TypeVisitable, TypeVisitor, }; use rustc_data_structures::fx::FxHashMap; -use rustc_errors::{Applicability, Diag, DiagArgValue, IntoDiagArg}; +use rustc_errors::{into_diag_arg_using_display, Applicability, Diag, DiagArgValue, IntoDiagArg}; use rustc_hir as hir; use rustc_hir::def::DefKind; use rustc_hir::def_id::DefId; @@ -19,10 +19,9 @@ use rustc_hir::{PredicateOrigin, WherePredicate}; use rustc_span::{BytePos, Span}; use rustc_type_ir::TyKind::*; -impl<'tcx> IntoDiagArg for Ty<'tcx> { - fn into_diag_arg(self) -> DiagArgValue { - self.to_string().into_diag_arg() - } +into_diag_arg_using_display! { + Ty<'_>, + ty::Region<'_>, } impl<'tcx> Ty<'tcx> { diff --git a/tests/ui/generic-associated-types/unsatisfied-item-lifetime-bound.rs b/tests/ui/generic-associated-types/unsatisfied-item-lifetime-bound.rs index a3f3b1a6d4d..e06341ddf31 100644 --- a/tests/ui/generic-associated-types/unsatisfied-item-lifetime-bound.rs +++ b/tests/ui/generic-associated-types/unsatisfied-item-lifetime-bound.rs @@ -1,8 +1,7 @@ -#![warn(unused_lifetimes)] +#![warn(unused_lifetimes, redundant_lifetimes)] pub trait X { - type Y<'a: 'static>; - //~^ WARNING unnecessary lifetime parameter + type Y<'a: 'static>; //~ WARN unnecessary lifetime parameter `'a` } impl X for () { diff --git a/tests/ui/generic-associated-types/unsatisfied-item-lifetime-bound.stderr b/tests/ui/generic-associated-types/unsatisfied-item-lifetime-bound.stderr index 8d21b9172c8..4f41ec025fc 100644 --- a/tests/ui/generic-associated-types/unsatisfied-item-lifetime-bound.stderr +++ b/tests/ui/generic-associated-types/unsatisfied-item-lifetime-bound.stderr @@ -1,18 +1,5 @@ -warning: unnecessary lifetime parameter `'a` - --> $DIR/unsatisfied-item-lifetime-bound.rs:4:12 - | -LL | type Y<'a: 'static>; - | ^^ - | - = help: you can use the `'static` lifetime directly, in place of `'a` -note: the lint level is defined here - --> $DIR/unsatisfied-item-lifetime-bound.rs:1:9 - | -LL | #![warn(unused_lifetimes)] - | ^^^^^^^^^^^^^^^^ - error[E0478]: lifetime bound not satisfied - --> $DIR/unsatisfied-item-lifetime-bound.rs:9:18 + --> $DIR/unsatisfied-item-lifetime-bound.rs:8:18 | LL | type Y<'a: 'static>; | ------------------- definition of `Y` from trait @@ -21,7 +8,7 @@ LL | type Y<'a> = &'a (); | ^^^^^^ | note: lifetime parameter instantiated with the lifetime `'a` as defined here - --> $DIR/unsatisfied-item-lifetime-bound.rs:9:12 + --> $DIR/unsatisfied-item-lifetime-bound.rs:8:12 | LL | type Y<'a> = &'a (); | ^^ @@ -32,44 +19,57 @@ LL | type Y<'a> = &'a () where 'a: 'static; | +++++++++++++++++ error[E0478]: lifetime bound not satisfied - --> $DIR/unsatisfied-item-lifetime-bound.rs:14:8 + --> $DIR/unsatisfied-item-lifetime-bound.rs:13:8 | LL | f: ::Y<'a>, | ^^^^^^^^^^^^^^^ | note: lifetime parameter instantiated with the lifetime `'a` as defined here - --> $DIR/unsatisfied-item-lifetime-bound.rs:13:10 + --> $DIR/unsatisfied-item-lifetime-bound.rs:12:10 | LL | struct B<'a, T: for<'r> X = &'r ()>> { | ^^ = note: but lifetime parameter must outlive the static lifetime error[E0478]: lifetime bound not satisfied - --> $DIR/unsatisfied-item-lifetime-bound.rs:19:8 + --> $DIR/unsatisfied-item-lifetime-bound.rs:18:8 | LL | f: ::Y<'a>, | ^^^^^^^^^^^^^^^ | note: lifetime parameter instantiated with the lifetime `'a` as defined here - --> $DIR/unsatisfied-item-lifetime-bound.rs:18:10 + --> $DIR/unsatisfied-item-lifetime-bound.rs:17:10 | LL | struct C<'a, T: X> { | ^^ = note: but lifetime parameter must outlive the static lifetime error[E0478]: lifetime bound not satisfied - --> $DIR/unsatisfied-item-lifetime-bound.rs:24:8 + --> $DIR/unsatisfied-item-lifetime-bound.rs:23:8 | LL | f: <() as X>::Y<'a>, | ^^^^^^^^^^^^^^^^ | note: lifetime parameter instantiated with the lifetime `'a` as defined here - --> $DIR/unsatisfied-item-lifetime-bound.rs:23:10 + --> $DIR/unsatisfied-item-lifetime-bound.rs:22:10 | LL | struct D<'a> { | ^^ = note: but lifetime parameter must outlive the static lifetime +warning: unnecessary lifetime parameter `'a` + --> $DIR/unsatisfied-item-lifetime-bound.rs:4:12 + | +LL | type Y<'a: 'static>; + | ^^ + | + = note: you can use the `'static` lifetime directly, in place of `'a` +note: the lint level is defined here + --> $DIR/unsatisfied-item-lifetime-bound.rs:1:27 + | +LL | #![warn(unused_lifetimes, redundant_lifetimes)] + | ^^^^^^^^^^^^^^^^^^^ + error: aborting due to 4 previous errors; 1 warning emitted For more information about this error, try `rustc --explain E0478`. diff --git a/tests/ui/regions/regions-free-region-outlives-static-outlives-free-region.rs b/tests/ui/regions/regions-free-region-outlives-static-outlives-free-region.rs index f6a628e97f5..bef0d70c776 100644 --- a/tests/ui/regions/regions-free-region-outlives-static-outlives-free-region.rs +++ b/tests/ui/regions/regions-free-region-outlives-static-outlives-free-region.rs @@ -8,10 +8,10 @@ // // 'a : 'b -#![warn(unused_lifetimes)] +#![warn(redundant_lifetimes)] -fn test<'a,'b>(x: &'a i32) -> &'b i32 - where 'a: 'static //~ WARN unnecessary lifetime parameter `'a` +fn test<'a,'b>(x: &'a i32) -> &'b i32 //~ WARN unnecessary lifetime parameter `'a` + where 'a: 'static { x } diff --git a/tests/ui/regions/regions-free-region-outlives-static-outlives-free-region.stderr b/tests/ui/regions/regions-free-region-outlives-static-outlives-free-region.stderr index 9f03a6553ba..d97cfd59f2b 100644 --- a/tests/ui/regions/regions-free-region-outlives-static-outlives-free-region.stderr +++ b/tests/ui/regions/regions-free-region-outlives-static-outlives-free-region.stderr @@ -1,15 +1,15 @@ warning: unnecessary lifetime parameter `'a` - --> $DIR/regions-free-region-outlives-static-outlives-free-region.rs:14:11 + --> $DIR/regions-free-region-outlives-static-outlives-free-region.rs:13:9 | -LL | where 'a: 'static - | ^^ +LL | fn test<'a,'b>(x: &'a i32) -> &'b i32 + | ^^ | - = help: you can use the `'static` lifetime directly, in place of `'a` + = note: you can use the `'static` lifetime directly, in place of `'a` note: the lint level is defined here --> $DIR/regions-free-region-outlives-static-outlives-free-region.rs:11:9 | -LL | #![warn(unused_lifetimes)] - | ^^^^^^^^^^^^^^^^ +LL | #![warn(redundant_lifetimes)] + | ^^^^^^^^^^^^^^^^^^^ warning: 1 warning emitted diff --git a/tests/ui/regions/regions-static-bound-rpass.rs b/tests/ui/regions/regions-static-bound-rpass.rs index 27da42882f3..f4177f835b1 100644 --- a/tests/ui/regions/regions-static-bound-rpass.rs +++ b/tests/ui/regions/regions-static-bound-rpass.rs @@ -1,18 +1,19 @@ //@ run-pass -#![warn(unused_lifetimes)] +#![warn(redundant_lifetimes)] fn invariant_id<'a,'b>(t: &'b mut &'static ()) -> &'b mut &'a () - where 'a: 'static { t } //~^ WARN unnecessary lifetime parameter `'a` + where 'a: 'static { t } fn static_id<'a>(t: &'a ()) -> &'static () - where 'a: 'static { t } //~^ WARN unnecessary lifetime parameter `'a` + where 'a: 'static { t } fn static_id_indirect<'a,'b>(t: &'a ()) -> &'static () +//~^ WARN unnecessary lifetime parameter `'a` +//~| WARN unnecessary lifetime parameter `'b` where 'a: 'b, 'b: 'static { t } -//~^ WARN unnecessary lifetime parameter `'b` fn ref_id<'a>(t: &'a ()) -> &'a () where 'static: 'a { t } diff --git a/tests/ui/regions/regions-static-bound-rpass.stderr b/tests/ui/regions/regions-static-bound-rpass.stderr index f0f3a4c5261..4199ac7bb3d 100644 --- a/tests/ui/regions/regions-static-bound-rpass.stderr +++ b/tests/ui/regions/regions-static-bound-rpass.stderr @@ -1,31 +1,39 @@ warning: unnecessary lifetime parameter `'a` - --> $DIR/regions-static-bound-rpass.rs:6:11 + --> $DIR/regions-static-bound-rpass.rs:5:17 | -LL | where 'a: 'static { t } - | ^^ +LL | fn invariant_id<'a,'b>(t: &'b mut &'static ()) -> &'b mut &'a () + | ^^ | - = help: you can use the `'static` lifetime directly, in place of `'a` + = note: you can use the `'static` lifetime directly, in place of `'a` note: the lint level is defined here --> $DIR/regions-static-bound-rpass.rs:3:9 | -LL | #![warn(unused_lifetimes)] - | ^^^^^^^^^^^^^^^^ +LL | #![warn(redundant_lifetimes)] + | ^^^^^^^^^^^^^^^^^^^ warning: unnecessary lifetime parameter `'a` - --> $DIR/regions-static-bound-rpass.rs:10:11 + --> $DIR/regions-static-bound-rpass.rs:9:14 | -LL | where 'a: 'static { t } - | ^^ +LL | fn static_id<'a>(t: &'a ()) -> &'static () + | ^^ | - = help: you can use the `'static` lifetime directly, in place of `'a` + = note: you can use the `'static` lifetime directly, in place of `'a` + +warning: unnecessary lifetime parameter `'a` + --> $DIR/regions-static-bound-rpass.rs:13:23 + | +LL | fn static_id_indirect<'a,'b>(t: &'a ()) -> &'static () + | ^^ + | + = note: you can use the `'static` lifetime directly, in place of `'a` warning: unnecessary lifetime parameter `'b` - --> $DIR/regions-static-bound-rpass.rs:14:19 + --> $DIR/regions-static-bound-rpass.rs:13:26 | -LL | where 'a: 'b, 'b: 'static { t } - | ^^ +LL | fn static_id_indirect<'a,'b>(t: &'a ()) -> &'static () + | ^^ | - = help: you can use the `'static` lifetime directly, in place of `'b` + = note: you can use the `'static` lifetime directly, in place of `'b` -warning: 3 warnings emitted +warning: 4 warnings emitted diff --git a/tests/ui/regions/regions-static-bound.rs b/tests/ui/regions/regions-static-bound.rs index e7aa8795f01..32fa2536533 100644 --- a/tests/ui/regions/regions-static-bound.rs +++ b/tests/ui/regions/regions-static-bound.rs @@ -1,12 +1,13 @@ -#![warn(unused_lifetimes)] +#![warn(unused_lifetimes, redundant_lifetimes)] fn static_id<'a,'b>(t: &'a ()) -> &'static () where 'a: 'static { t } -//~^ WARN lifetime parameter `'b` never used -//~| WARN unnecessary lifetime parameter `'a` +//~^ WARN unnecessary lifetime parameter `'a` +//~| WARN lifetime parameter `'b` never used fn static_id_indirect<'a,'b>(t: &'a ()) -> &'static () +//~^ WARN unnecessary lifetime parameter `'a` +//~| WARN unnecessary lifetime parameter `'b` where 'a: 'b, 'b: 'static { t } -//~^ WARN unnecessary lifetime parameter `'b` fn static_id_wrong_way<'a>(t: &'a ()) -> &'static () where 'static: 'a { t diff --git a/tests/ui/regions/regions-static-bound.stderr b/tests/ui/regions/regions-static-bound.stderr index b314e9fe85d..48aa8f32329 100644 --- a/tests/ui/regions/regions-static-bound.stderr +++ b/tests/ui/regions/regions-static-bound.stderr @@ -9,27 +9,40 @@ LL | fn static_id<'a,'b>(t: &'a ()) -> &'static () where 'a: 'static { t } note: the lint level is defined here --> $DIR/regions-static-bound.rs:1:9 | -LL | #![warn(unused_lifetimes)] +LL | #![warn(unused_lifetimes, redundant_lifetimes)] | ^^^^^^^^^^^^^^^^ warning: unnecessary lifetime parameter `'a` - --> $DIR/regions-static-bound.rs:3:53 + --> $DIR/regions-static-bound.rs:3:14 | LL | fn static_id<'a,'b>(t: &'a ()) -> &'static () where 'a: 'static { t } - | ^^ + | ^^ | - = help: you can use the `'static` lifetime directly, in place of `'a` + = note: you can use the `'static` lifetime directly, in place of `'a` +note: the lint level is defined here + --> $DIR/regions-static-bound.rs:1:27 + | +LL | #![warn(unused_lifetimes, redundant_lifetimes)] + | ^^^^^^^^^^^^^^^^^^^ + +warning: unnecessary lifetime parameter `'a` + --> $DIR/regions-static-bound.rs:7:23 + | +LL | fn static_id_indirect<'a,'b>(t: &'a ()) -> &'static () + | ^^ + | + = note: you can use the `'static` lifetime directly, in place of `'a` warning: unnecessary lifetime parameter `'b` - --> $DIR/regions-static-bound.rs:8:19 + --> $DIR/regions-static-bound.rs:7:26 | -LL | where 'a: 'b, 'b: 'static { t } - | ^^ +LL | fn static_id_indirect<'a,'b>(t: &'a ()) -> &'static () + | ^^ | - = help: you can use the `'static` lifetime directly, in place of `'b` + = note: you can use the `'static` lifetime directly, in place of `'b` error: lifetime may not live long enough - --> $DIR/regions-static-bound.rs:12:5 + --> $DIR/regions-static-bound.rs:13:5 | LL | fn static_id_wrong_way<'a>(t: &'a ()) -> &'static () where 'static: 'a { | -- lifetime `'a` defined here @@ -37,7 +50,7 @@ LL | t | ^ returning this value requires that `'a` must outlive `'static` error[E0521]: borrowed data escapes outside of function - --> $DIR/regions-static-bound.rs:17:5 + --> $DIR/regions-static-bound.rs:18:5 | LL | fn error(u: &(), v: &()) { | - - let's call the lifetime of this reference `'1` @@ -50,7 +63,7 @@ LL | static_id(&u); | argument requires that `'1` must outlive `'static` error[E0521]: borrowed data escapes outside of function - --> $DIR/regions-static-bound.rs:19:5 + --> $DIR/regions-static-bound.rs:20:5 | LL | fn error(u: &(), v: &()) { | - - let's call the lifetime of this reference `'2` @@ -63,6 +76,6 @@ LL | static_id_indirect(&v); | `v` escapes the function body here | argument requires that `'2` must outlive `'static` -error: aborting due to 3 previous errors; 3 warnings emitted +error: aborting due to 3 previous errors; 4 warnings emitted For more information about this error, try `rustc --explain E0521`. diff --git a/tests/ui/regions/transitively-redundant-lifetimes.rs b/tests/ui/regions/transitively-redundant-lifetimes.rs new file mode 100644 index 00000000000..9c29f66e54c --- /dev/null +++ b/tests/ui/regions/transitively-redundant-lifetimes.rs @@ -0,0 +1,20 @@ +#![deny(redundant_lifetimes)] + +fn a<'a, 'b>(x: &'a &'b &'a ()) {} //~ ERROR unnecessary lifetime parameter `'b` + +fn b<'a: 'b, 'b: 'a>() {} //~ ERROR unnecessary lifetime parameter `'b` + +struct Foo(T); +fn c<'a>(_: Foo<&'a ()>) {} //~ ERROR unnecessary lifetime parameter `'a` + +struct Bar<'a>(&'a ()); +impl<'a> Bar<'a> { + fn d<'b: 'a>(&'b self) {} //~ ERROR unnecessary lifetime parameter `'b` +} + +fn ok(x: &'static &()) {} + +trait Tr<'a> {} +impl<'a: 'static> Tr<'a> for () {} //~ ERROR unnecessary lifetime parameter `'a` + +fn main() {} diff --git a/tests/ui/regions/transitively-redundant-lifetimes.stderr b/tests/ui/regions/transitively-redundant-lifetimes.stderr new file mode 100644 index 00000000000..2d8fc433b24 --- /dev/null +++ b/tests/ui/regions/transitively-redundant-lifetimes.stderr @@ -0,0 +1,47 @@ +error: unnecessary lifetime parameter `'b` + --> $DIR/transitively-redundant-lifetimes.rs:3:10 + | +LL | fn a<'a, 'b>(x: &'a &'b &'a ()) {} + | ^^ + | + = note: you can use the `'a` lifetime directly, in place of `'b` +note: the lint level is defined here + --> $DIR/transitively-redundant-lifetimes.rs:1:9 + | +LL | #![deny(redundant_lifetimes)] + | ^^^^^^^^^^^^^^^^^^^ + +error: unnecessary lifetime parameter `'b` + --> $DIR/transitively-redundant-lifetimes.rs:5:14 + | +LL | fn b<'a: 'b, 'b: 'a>() {} + | ^^ + | + = note: you can use the `'a` lifetime directly, in place of `'b` + +error: unnecessary lifetime parameter `'a` + --> $DIR/transitively-redundant-lifetimes.rs:8:6 + | +LL | fn c<'a>(_: Foo<&'a ()>) {} + | ^^ + | + = note: you can use the `'static` lifetime directly, in place of `'a` + +error: unnecessary lifetime parameter `'a` + --> $DIR/transitively-redundant-lifetimes.rs:18:6 + | +LL | impl<'a: 'static> Tr<'a> for () {} + | ^^ + | + = note: you can use the `'static` lifetime directly, in place of `'a` + +error: unnecessary lifetime parameter `'b` + --> $DIR/transitively-redundant-lifetimes.rs:12:10 + | +LL | fn d<'b: 'a>(&'b self) {} + | ^^ + | + = note: you can use the `'a` lifetime directly, in place of `'b` + +error: aborting due to 5 previous errors +