Updated suggestion/help messages.
This commit is contained in:
David Wood
parent
7a89e93519
commit
37e18b1c51
3 changed files with 44 additions and 48 deletions
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@ -15,7 +15,7 @@ use rustc::hir::def_id::DefId;
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use rustc::infer::error_reporting::nice_region_error::NiceRegionError;
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use rustc::infer::InferCtxt;
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use rustc::mir::{self, Location, Mir, Place, Rvalue, StatementKind, TerminatorKind};
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use rustc::ty::{self, TyCtxt, Region, RegionKind, RegionVid};
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use rustc::ty::{self, TyCtxt, RegionVid};
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use rustc_data_structures::indexed_vec::IndexVec;
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use rustc_errors::{Diagnostic, DiagnosticBuilder};
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use std::collections::VecDeque;
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@ -347,9 +347,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
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);
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// Check if we can use one of the "nice region errors".
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let fr_region = self.to_error_region(fr);
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let outlived_fr_region = self.to_error_region(outlived_fr);
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if let (Some(f), Some(o)) = (fr_region, outlived_fr_region) {
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if let (Some(f), Some(o)) = (self.to_error_region(fr), self.to_error_region(outlived_fr)) {
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let tables = infcx.tcx.typeck_tables_of(mir_def_id);
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let nice = NiceRegionError::new_from_span(infcx.tcx, span, o, f, Some(tables));
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if let Some(_error_reported) = nice.try_report_from_nll() {
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@ -362,17 +360,16 @@ impl<'tcx> RegionInferenceContext<'tcx> {
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self.universal_regions.is_local_free_region(outlived_fr),
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);
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debug!("report_error: fr_is_local={:?} outlived_fr_is_local={:?} fr_region={:?} \
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outlived_fr_region={:?} category={:?}",
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fr_is_local, outlived_fr_is_local, fr_region, outlived_fr_region, category);
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debug!("report_error: fr_is_local={:?} outlived_fr_is_local={:?} category={:?}",
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fr_is_local, outlived_fr_is_local, category);
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match (category, fr_is_local, outlived_fr_is_local) {
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(ConstraintCategory::Assignment, true, false) |
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(ConstraintCategory::CallArgument, true, false) =>
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self.report_escaping_data_error(mir, infcx, mir_def_id, fr, fr_region, outlived_fr,
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outlived_fr_region, category, span, errors_buffer),
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self.report_escaping_data_error(mir, infcx, mir_def_id, fr, outlived_fr,
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category, span, errors_buffer),
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_ =>
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self.report_general_error(mir, infcx, mir_def_id, fr, fr_is_local, fr_region,
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outlived_fr, outlived_fr_is_local, outlived_fr_region,
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self.report_general_error(mir, infcx, mir_def_id, fr, fr_is_local,
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outlived_fr, outlived_fr_is_local,
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category, span, errors_buffer),
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};
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}
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@ -383,9 +380,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
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infcx: &InferCtxt<'_, '_, 'tcx>,
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mir_def_id: DefId,
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fr: RegionVid,
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fr_region: Option<Region<'tcx>>,
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outlived_fr: RegionVid,
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outlived_fr_region: Option<Region<'tcx>>,
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category: ConstraintCategory,
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span: Span,
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errors_buffer: &mut Vec<Diagnostic>,
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@ -398,8 +393,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
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if fr_name_and_span.is_none() && outlived_fr_name_and_span.is_none() {
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return self.report_general_error(mir, infcx, mir_def_id,
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fr, true, fr_region,
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outlived_fr, false, outlived_fr_region,
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fr, true, outlived_fr, false,
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category, span, errors_buffer);
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}
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@ -439,10 +433,8 @@ impl<'tcx> RegionInferenceContext<'tcx> {
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mir_def_id: DefId,
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fr: RegionVid,
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fr_is_local: bool,
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fr_region: Option<Region<'tcx>>,
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outlived_fr: RegionVid,
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outlived_fr_is_local: bool,
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outlived_fr_region: Option<Region<'tcx>>,
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category: ConstraintCategory,
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span: Span,
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errors_buffer: &mut Vec<Diagnostic>,
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@ -477,7 +469,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
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}
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self.add_static_impl_trait_suggestion(
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infcx, &mut diag, fr_name, fr_region, outlived_fr_region
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infcx, &mut diag, fr, fr_name, outlived_fr,
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);
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diag.buffer(errors_buffer);
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@ -487,11 +479,15 @@ impl<'tcx> RegionInferenceContext<'tcx> {
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&self,
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infcx: &InferCtxt<'_, '_, 'tcx>,
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diag: &mut DiagnosticBuilder<'_>,
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fr: RegionVid,
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// We need to pass `fr_name` - computing it again will label it twice.
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fr_name: RegionName,
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fr_region: Option<Region<'tcx>>,
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outlived_fr_region: Option<Region<'tcx>>,
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outlived_fr: RegionVid,
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) {
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if let (Some(f), Some(ty::RegionKind::ReStatic)) = (fr_region, outlived_fr_region) {
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if let (
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Some(f),
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Some(ty::RegionKind::ReStatic)
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) = (self.to_error_region(fr), self.to_error_region(outlived_fr)) {
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if let Some(ty::TyS {
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sty: ty::TyKind::Anon(did, substs),
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..
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@ -500,6 +496,10 @@ impl<'tcx> RegionInferenceContext<'tcx> {
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.map(|id| infcx.tcx.return_type_impl_trait(id))
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.unwrap_or(None)
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{
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// Check whether or not the impl trait return type is intended to capture
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// data with the static lifetime.
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//
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// eg. check for `impl Trait + 'static` instead of `impl Trait`.
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let has_static_predicate = {
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let predicates_of = infcx.tcx.predicates_of(*did);
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let bounds = predicates_of.instantiate(infcx.tcx, substs);
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@ -509,7 +509,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
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if let ty::Predicate::TypeOutlives(binder) = predicate {
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if let ty::OutlivesPredicate(
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_,
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RegionKind::ReStatic
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ty::RegionKind::ReStatic
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) = binder.skip_binder() {
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found = true;
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break;
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@ -523,33 +523,31 @@ impl<'tcx> RegionInferenceContext<'tcx> {
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debug!("add_static_impl_trait_suggestion: has_static_predicate={:?}",
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has_static_predicate);
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let static_str = keywords::StaticLifetime.name();
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// If there is a static predicate, then the only sensible suggestion is to replace
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// fr with `'static`.
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if has_static_predicate {
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let span = self.get_span_of_named_region(infcx.tcx, f, &fr_name);
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if let Ok(snippet) = infcx.tcx.sess.source_map().span_to_snippet(span) {
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diag.span_suggestion(
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span,
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&format!(
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"you can add a constraint to the definition of `{}` to require it \
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outlive `{}`",
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fr_name, static_str,
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),
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format!("{}: {}", snippet, static_str),
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);
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}
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diag.help(
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&format!(
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"consider replacing `{}` with `{}`",
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fr_name, static_str,
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),
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);
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} else {
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// Otherwise, we should suggest adding a constraint on the return type.
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let span = infcx.tcx.def_span(*did);
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if let Ok(snippet) = infcx.tcx.sess.source_map().span_to_snippet(span) {
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let suggestable_fr_name = match fr_name {
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RegionName::Named(name) => format!("{}", name),
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RegionName::Synthesized(_) => "'_".to_string(),
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};
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diag.span_suggestion(
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span,
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&format!(
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"you can add a constraint to the return type to make it last \
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less than `{}` and match `{}`",
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static_str, fr_name,
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"to allow this impl Trait to capture borrowed data with lifetime \
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`{}`, add `{}` as a constraint",
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fr_name, suggestable_fr_name,
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),
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match fr_name {
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RegionName::Named(name) => format!("{} + {}", snippet, name),
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RegionName::Synthesized(_) => format!("{} + '_", snippet),
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},
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format!("{} + {}", snippet, suggestable_fr_name),
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);
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}
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}
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@ -11,7 +11,7 @@ error: unsatisfied lifetime constraints
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LL | fn explicit<'a>(x: &'a i32) -> impl Copy { x }
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| -- lifetime `'a` defined here ^ returning this value requires that `'a` must outlive `'static`
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help: you can add a constraint to the return type to make it last less than `'static` and match `'a`
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help: to allow this impl Trait to capture borrowed data with lifetime `'a`, add `'a` as a constraint
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LL | fn explicit<'a>(x: &'a i32) -> impl Copy + 'a { x }
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| ^^^^^^^^^^^^^^
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@ -21,10 +21,8 @@ error: unsatisfied lifetime constraints
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LL | fn with_bound<'a>(x: &'a i32) -> impl LifetimeTrait<'a> + 'static { x }
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| -- lifetime `'a` defined here ^ returning this value requires that `'a` must outlive `'static`
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help: you can add a constraint to the definition of `'a` to require it outlive `'static`
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LL | fn with_bound<'a: 'static>(x: &'a i32) -> impl LifetimeTrait<'a> + 'static { x }
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| ^^^^^^^^^^^
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= help: consider replacing `'a` with `'static`
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error: unsatisfied lifetime constraints
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--> $DIR/must_outlive_least_region_or_bound.rs:29:5
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@ -5,9 +5,9 @@ LL | fn iter_values_anon(&self) -> impl Iterator<Item=u32> {
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| - let's call the lifetime of this reference `'1`
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LL | self.x.iter().map(|a| a.0)
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| ^^^^^^ cast requires that `'1` must outlive `'static`
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help: you can add a constraint to the return type to make it last less than `'static` and match '1
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help: to allow this impl Trait to capture borrowed data with lifetime `'1`, add `'_` as a constraint
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LL | fn iter_values_anon(&self) -> impl Iterator<Item=u32> + '1 {
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LL | fn iter_values_anon(&self) -> impl Iterator<Item=u32> + '_ {
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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error: unsatisfied lifetime constraints
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@ -17,7 +17,7 @@ LL | fn iter_values<'a>(&'a self) -> impl Iterator<Item=u32> {
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| -- lifetime `'a` defined here
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LL | self.x.iter().map(|a| a.0)
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| ^^^^^^ cast requires that `'a` must outlive `'static`
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help: you can add a constraint to the return type to make it last less than `'static` and match 'a
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help: to allow this impl Trait to capture borrowed data with lifetime `'a`, add `'a` as a constraint
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LL | fn iter_values<'a>(&'a self) -> impl Iterator<Item=u32> + 'a {
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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