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Rollup merge of #82370 - 0yoyoyo:update-issue-81650-point-anonymous-lifetime, r=estebank

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Improve anonymous lifetime note to indicate the target span

Improvement for  #81650
Cc #81995

Message after this improvement:
(Improve note in the middle)

```
error[E0311]: the parameter type `T` may not live long enough
  --> src/main.rs:25:11
   |
24 | fn play_with<T: Animal + Send>(scope: &Scope, animal: T) {
   |              -- help: consider adding an explicit lifetime bound...: `T: 'a +`
25 |     scope.spawn(move |_| {
   |           ^^^^^
   |
note: the parameter type `T` must be valid for the anonymous lifetime defined on the function body at 24:40...
  --> src/main.rs:24:40
   |
24 | fn play_with<T: Animal + Send>(scope: &Scope, animal: T) {
   |                                        ^^^^^
note: ...so that the type `[closure@src/main.rs:25:17: 27:6]` will meet its required lifetime bounds
  --> src/main.rs:25:11
   |
25 |     scope.spawn(move |_| {
   |           ^^^^^
```

r? ``````@estebank``````
This commit is contained in:
Dylan DPC 2021-02-27 02:34:22 +01:00 • committed by GitHub
commit f0c98b15cc
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20 changed files with 157 additions and 166 deletions
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10
compiler/rustc_infer/src/infer/error_reporting/mod.rs
View file

@ -50,6 +50,7 @@ use super::region_constraints::GenericKind;
use super::{InferCtxt, RegionVariableOrigin, SubregionOrigin, TypeTrace, ValuePairs};
use crate::infer;
use crate::infer::error_reporting::nice_region_error::find_anon_type::find_anon_type;
use crate::traits::error_reporting::report_object_safety_error;
use crate::traits::{
IfExpressionCause, MatchExpressionArmCause, ObligationCause, ObligationCauseCode,
@ -179,7 +180,14 @@ fn msg_span_from_early_bound_and_free_regions(
}
ty::ReFree(ref fr) => match fr.bound_region {
ty::BrAnon(idx) => {
(format!("the anonymous lifetime #{} defined on", idx + 1), tcx.hir().span(node))
if let Some((ty, _)) = find_anon_type(tcx, region, &fr.bound_region) {
("the anonymous lifetime defined on".to_string(), ty.span)
} else {
(
format!("the anonymous lifetime #{} defined on", idx + 1),
tcx.hir().span(node),
)
}
}
_ => (
format!("the lifetime `{}` as defined on", region),

5
compiler/rustc_infer/src/infer/error_reporting/nice_region_error/different_lifetimes.rs
View file

@ -1,6 +1,7 @@
//! Error Reporting for Anonymous Region Lifetime Errors
//! where both the regions are anonymous.
use crate::infer::error_reporting::nice_region_error::find_anon_type::find_anon_type;
use crate::infer::error_reporting::nice_region_error::util::AnonymousParamInfo;
use crate::infer::error_reporting::nice_region_error::NiceRegionError;
use crate::infer::lexical_region_resolve::RegionResolutionError;
@ -66,9 +67,9 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
let scope_def_id_sub = anon_reg_sub.def_id;
let bregion_sub = anon_reg_sub.boundregion;
let ty_sup = self.find_anon_type(sup, &bregion_sup)?;
let ty_sup = find_anon_type(self.tcx(), sup, &bregion_sup)?;
let ty_sub = self.find_anon_type(sub, &bregion_sub)?;
let ty_sub = find_anon_type(self.tcx(), sub, &bregion_sub)?;
debug!(
"try_report_anon_anon_conflict: found_param1={:?} sup={:?} br1={:?}",

116
compiler/rustc_infer/src/infer/error_reporting/nice_region_error/find_anon_type.rs
View file

@ -1,4 +1,3 @@
use crate::infer::error_reporting::nice_region_error::NiceRegionError;
use rustc_hir as hir;
use rustc_hir::intravisit::{self, NestedVisitorMap, Visitor};
use rustc_hir::Node;
@ -6,69 +5,66 @@ use rustc_middle::hir::map::Map;
use rustc_middle::middle::resolve_lifetime as rl;
use rustc_middle::ty::{self, Region, TyCtxt};
impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
/// This function calls the `visit_ty` method for the parameters
/// corresponding to the anonymous regions. The `nested_visitor.found_type`
/// contains the anonymous type.
///
/// # Arguments
/// region - the anonymous region corresponding to the anon_anon conflict
/// br - the bound region corresponding to the above region which is of type `BrAnon(_)`
///
/// # Example
/// ```
/// fn foo(x: &mut Vec<&u8>, y: &u8)
/// { x.push(y); }
/// ```
/// The function returns the nested type corresponding to the anonymous region
/// for e.g., `&u8` and Vec<`&u8`.
pub(super) fn find_anon_type(
&self,
region: Region<'tcx>,
br: &ty::BoundRegionKind,
) -> Option<(&hir::Ty<'tcx>, &hir::FnDecl<'tcx>)> {
if let Some(anon_reg) = self.tcx().is_suitable_region(region) {
let hir_id = self.tcx().hir().local_def_id_to_hir_id(anon_reg.def_id);
let fndecl = match self.tcx().hir().get(hir_id) {
Node::Item(&hir::Item { kind: hir::ItemKind::Fn(ref m, ..), .. })
| Node::TraitItem(&hir::TraitItem {
kind: hir::TraitItemKind::Fn(ref m, ..),
..
})
| Node::ImplItem(&hir::ImplItem {
kind: hir::ImplItemKind::Fn(ref m, ..), ..
}) => &m.decl,
_ => return None,
};
fndecl
.inputs
.iter()
.find_map(|arg| self.find_component_for_bound_region(arg, br))
.map(|ty| (ty, &**fndecl))
} else {
None
}
}
// This method creates a FindNestedTypeVisitor which returns the type corresponding
// to the anonymous region.
fn find_component_for_bound_region(
&self,
arg: &'tcx hir::Ty<'tcx>,
br: &ty::BoundRegionKind,
) -> Option<&'tcx hir::Ty<'tcx>> {
let mut nested_visitor = FindNestedTypeVisitor {
tcx: self.tcx(),
bound_region: *br,
found_type: None,
current_index: ty::INNERMOST,
/// This function calls the `visit_ty` method for the parameters
/// corresponding to the anonymous regions. The `nested_visitor.found_type`
/// contains the anonymous type.
///
/// # Arguments
/// region - the anonymous region corresponding to the anon_anon conflict
/// br - the bound region corresponding to the above region which is of type `BrAnon(_)`
///
/// # Example
/// ```
/// fn foo(x: &mut Vec<&u8>, y: &u8)
/// { x.push(y); }
/// ```
/// The function returns the nested type corresponding to the anonymous region
/// for e.g., `&u8` and Vec<`&u8`.
pub(crate) fn find_anon_type(
tcx: TyCtxt<'tcx>,
region: Region<'tcx>,
br: &ty::BoundRegionKind,
) -> Option<(&'tcx hir::Ty<'tcx>, &'tcx hir::FnDecl<'tcx>)> {
if let Some(anon_reg) = tcx.is_suitable_region(region) {
let hir_id = tcx.hir().local_def_id_to_hir_id(anon_reg.def_id);
let fndecl = match tcx.hir().get(hir_id) {
Node::Item(&hir::Item { kind: hir::ItemKind::Fn(ref m, ..), .. })
| Node::TraitItem(&hir::TraitItem {
kind: hir::TraitItemKind::Fn(ref m, ..), ..
})
| Node::ImplItem(&hir::ImplItem { kind: hir::ImplItemKind::Fn(ref m, ..), .. }) => {
&m.decl
}
_ => return None,
};
nested_visitor.visit_ty(arg);
nested_visitor.found_type
fndecl
.inputs
.iter()
.find_map(|arg| find_component_for_bound_region(tcx, arg, br))
.map(|ty| (ty, &**fndecl))
} else {
None
}
}
// This method creates a FindNestedTypeVisitor which returns the type corresponding
// to the anonymous region.
fn find_component_for_bound_region(
tcx: TyCtxt<'tcx>,
arg: &'tcx hir::Ty<'tcx>,
br: &ty::BoundRegionKind,
) -> Option<&'tcx hir::Ty<'tcx>> {
let mut nested_visitor = FindNestedTypeVisitor {
tcx,
bound_region: *br,
found_type: None,
current_index: ty::INNERMOST,
};
nested_visitor.visit_ty(arg);
nested_visitor.found_type
}
// The FindNestedTypeVisitor captures the corresponding `hir::Ty` of the
// anonymous region. The example above would lead to a conflict between
// the two anonymous lifetimes for &u8 in x and y respectively. This visitor

2
compiler/rustc_infer/src/infer/error_reporting/nice_region_error/mod.rs
View file

@ -6,7 +6,7 @@ use rustc_middle::ty::{self, TyCtxt};
use rustc_span::source_map::Span;
mod different_lifetimes;
mod find_anon_type;
pub mod find_anon_type;
mod named_anon_conflict;
mod placeholder_error;
mod static_impl_trait;

3
compiler/rustc_infer/src/infer/error_reporting/nice_region_error/named_anon_conflict.rs
View file

@ -1,5 +1,6 @@
//! Error Reporting for Anonymous Region Lifetime Errors
//! where one region is named and the other is anonymous.
use crate::infer::error_reporting::nice_region_error::find_anon_type::find_anon_type;
use crate::infer::error_reporting::nice_region_error::NiceRegionError;
use rustc_errors::{struct_span_err, Applicability, DiagnosticBuilder};
use rustc_hir::intravisit::Visitor;
@ -74,7 +75,7 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
return None;
}
if let Some((_, fndecl)) = self.find_anon_type(anon, &br) {
if let Some((_, fndecl)) = find_anon_type(self.tcx(), anon, &br) {
if self.is_self_anon(is_first, scope_def_id) {
return None;
}