Rollup of 5 pull requests

compiler/rustc_borrowck/src/diagnostics/region_errors.rs

@@ -1,17 +1,17 @@
 //! Error reporting machinery for lifetime errors.
 
-use rustc_errors::{Applicability, Diagnostic, DiagnosticBuilder, ErrorGuaranteed};
+use rustc_errors::{Diagnostic, DiagnosticBuilder, ErrorGuaranteed};
 use rustc_infer::infer::{
-    error_reporting::nice_region_error::NiceRegionError,
-    error_reporting::unexpected_hidden_region_diagnostic, NllRegionVariableOrigin,
-    RelateParamBound,
+    error_reporting::nice_region_error::{self, find_param_with_region, NiceRegionError},
+    error_reporting::unexpected_hidden_region_diagnostic,
+    NllRegionVariableOrigin, RelateParamBound,
 };
 use rustc_middle::hir::place::PlaceBase;
 use rustc_middle::mir::{ConstraintCategory, ReturnConstraint};
-use rustc_middle::ty::subst::{InternalSubsts, Subst};
+use rustc_middle::ty::subst::InternalSubsts;
 use rustc_middle::ty::{self, RegionVid, Ty};
-use rustc_span::symbol::{kw, sym};
-use rustc_span::{BytePos, Span};
+use rustc_span::symbol::sym;
+use rustc_span::Span;
 
 use crate::borrowck_errors;
 
@@ -651,82 +651,47 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
         fr_name: RegionName,
         outlived_fr: RegionVid,
     ) {
-        if let (Some(f), Some(ty::ReStatic)) =
-            (self.to_error_region(fr), self.to_error_region(outlived_fr).as_deref())
+        if let (Some(f), Some(outlived_f)) =
+            (self.to_error_region(fr), self.to_error_region(outlived_fr))
         {
-            if let Some(&ty::Opaque(did, substs)) = self
+            if *outlived_f != ty::ReStatic {
+                return;
+            }
+
+            let fn_returns = self
                 .infcx
                 .tcx
                 .is_suitable_region(f)
-                .map(|r| r.def_id)
-                .and_then(|id| self.infcx.tcx.return_type_impl_trait(id))
-                .map(|(ty, _)| ty.kind())
-            {
-                // Check whether or not the impl trait return type is intended to capture
-                // data with the static lifetime.
-                //
-                // eg. check for `impl Trait + 'static` instead of `impl Trait`.
-                let has_static_predicate = {
-                    let bounds = self.infcx.tcx.explicit_item_bounds(did);
-
-                    let mut found = false;
-                    for (bound, _) in bounds {
-                        if let ty::PredicateKind::TypeOutlives(ty::OutlivesPredicate(_, r)) =
-                            bound.kind().skip_binder()
-                        {
-                            let r = r.subst(self.infcx.tcx, substs);
-                            if r.is_static() {
-                                found = true;
-                                break;
-                            } else {
-                                // If there's already a lifetime bound, don't
-                                // suggest anything.
-                                return;
-                            }
-                        }
-                    }
-
-                    found
-                };
+                .map(|r| self.infcx.tcx.return_type_impl_or_dyn_traits(r.def_id))
+                .unwrap_or_default();
 
-                debug!(
-                    "add_static_impl_trait_suggestion: has_static_predicate={:?}",
-                    has_static_predicate
-                );
-                let static_str = kw::StaticLifetime;
-                // If there is a static predicate, then the only sensible suggestion is to replace
-                // fr with `'static`.
-                if has_static_predicate {
-                    diag.help(&format!("consider replacing `{fr_name}` with `{static_str}`"));
-                } else {
-                    // Otherwise, we should suggest adding a constraint on the return type.
-                    let span = self.infcx.tcx.def_span(did);
-                    if let Ok(snippet) = self.infcx.tcx.sess.source_map().span_to_snippet(span) {
-                        let suggestable_fr_name = if fr_name.was_named() {
-                            fr_name.to_string()
-                        } else {
-                            "'_".to_string()
-                        };
-                        let span = if snippet.ends_with(';') {
-                            // `type X = impl Trait;`
-                            span.with_hi(span.hi() - BytePos(1))
-                        } else {
-                            span
-                        };
-                        let suggestion = format!(" + {suggestable_fr_name}");
-                        let span = span.shrink_to_hi();
-                        diag.span_suggestion(
-                            span,
-                            &format!(
-                                "to allow this `impl Trait` to capture borrowed data with lifetime \
-                                 `{fr_name}`, add `{suggestable_fr_name}` as a bound",
-                            ),
-                            suggestion,
-                            Applicability::MachineApplicable,
-                        );
-                    }
-                }
+            if fn_returns.is_empty() {
+                return;
             }
+
+            let param = if let Some(param) = find_param_with_region(self.infcx.tcx, f, outlived_f) {
+                param
+            } else {
+                return;
+            };
+
+            let lifetime = if f.has_name() { fr_name.to_string() } else { "'_".to_string() };
+
+            let arg = match param.param.pat.simple_ident() {
+                Some(simple_ident) => format!("argument `{}`", simple_ident),
+                None => "the argument".to_string(),
+            };
+            let captures = format!("captures data from {}", arg);
+
+            return nice_region_error::suggest_new_region_bound(
+                self.infcx.tcx,
+                diag,
+                fn_returns,
+                lifetime,
+                Some(arg),
+                captures,
+                Some((param.param_ty_span, param.param_ty.to_string())),
+            );
         }
     }
 }

compiler/rustc_infer/src/infer/error_reporting/nice_region_error/mod.rs

@@ -15,6 +15,7 @@ mod trait_impl_difference;
 mod util;
 
 pub use static_impl_trait::suggest_new_region_bound;
+pub use util::find_param_with_region;
 
 impl<'cx, 'tcx> InferCtxt<'cx, 'tcx> {
     pub fn try_report_nice_region_error(&self, error: &RegionResolutionError<'tcx>) -> bool {

compiler/rustc_infer/src/infer/error_reporting/nice_region_error/util.rs

@@ -2,14 +2,15 @@
 //! anonymous regions.
 
 use crate::infer::error_reporting::nice_region_error::NiceRegionError;
+use crate::infer::TyCtxt;
 use rustc_hir as hir;
 use rustc_hir::def_id::LocalDefId;
 use rustc_middle::ty::{self, Binder, DefIdTree, Region, Ty, TypeFoldable};
 use rustc_span::Span;
 
 /// Information about the anonymous region we are searching for.
 #[derive(Debug)]
-pub(super) struct AnonymousParamInfo<'tcx> {
+pub struct AnonymousParamInfo<'tcx> {
     /// The parameter corresponding to the anonymous region.
     pub param: &'tcx hir::Param<'tcx>,
     /// The type corresponding to the anonymous region parameter.
@@ -22,76 +23,83 @@ pub(super) struct AnonymousParamInfo<'tcx> {
     pub is_first: bool,
 }
 
+// This method walks the Type of the function body parameters using
+// `fold_regions()` function and returns the
+// &hir::Param of the function parameter corresponding to the anonymous
+// region and the Ty corresponding to the named region.
+// Currently only the case where the function declaration consists of
+// one named region and one anonymous region is handled.
+// Consider the example `fn foo<'a>(x: &'a i32, y: &i32) -> &'a i32`
+// Here, we would return the hir::Param for y, we return the type &'a
+// i32, which is the type of y but with the anonymous region replaced
+// with 'a, the corresponding bound region and is_first which is true if
+// the hir::Param is the first parameter in the function declaration.
+pub fn find_param_with_region<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    anon_region: Region<'tcx>,
+    replace_region: Region<'tcx>,
+) -> Option<AnonymousParamInfo<'tcx>> {
+    let (id, bound_region) = match *anon_region {
+        ty::ReFree(ref free_region) => (free_region.scope, free_region.bound_region),
+        ty::ReEarlyBound(ebr) => {
+            (tcx.parent(ebr.def_id).unwrap(), ty::BoundRegionKind::BrNamed(ebr.def_id, ebr.name))
+        }
+        _ => return None, // not a free region
+    };
+
+    let hir = &tcx.hir();
+    let hir_id = hir.local_def_id_to_hir_id(id.as_local()?);
+    let body_id = hir.maybe_body_owned_by(hir_id)?;
+    let body = hir.body(body_id);
+    let owner_id = hir.body_owner(body_id);
+    let fn_decl = hir.fn_decl_by_hir_id(owner_id).unwrap();
+    let poly_fn_sig = tcx.fn_sig(id);
+    let fn_sig = tcx.liberate_late_bound_regions(id, poly_fn_sig);
+    body.params
+        .iter()
+        .take(if fn_sig.c_variadic {
+            fn_sig.inputs().len()
+        } else {
+            assert_eq!(fn_sig.inputs().len(), body.params.len());
+            body.params.len()
+        })
+        .enumerate()
+        .find_map(|(index, param)| {
+            // May return None; sometimes the tables are not yet populated.
+            let ty = fn_sig.inputs()[index];
+            let mut found_anon_region = false;
+            let new_param_ty = tcx.fold_regions(ty, &mut false, |r, _| {
+                if r == anon_region {
+                    found_anon_region = true;
+                    replace_region
+                } else {
+                    r
+                }
+            });
+            if found_anon_region {
+                let ty_hir_id = fn_decl.inputs[index].hir_id;
+                let param_ty_span = hir.span(ty_hir_id);
+                let is_first = index == 0;
+                Some(AnonymousParamInfo {
+                    param,
+                    param_ty: new_param_ty,
+                    param_ty_span,
+                    bound_region,
+                    is_first,
+                })
+            } else {
+                None
+            }
+        })
+}
+
 impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
-    // This method walks the Type of the function body parameters using
-    // `fold_regions()` function and returns the
-    // &hir::Param of the function parameter corresponding to the anonymous
-    // region and the Ty corresponding to the named region.
-    // Currently only the case where the function declaration consists of
-    // one named region and one anonymous region is handled.
-    // Consider the example `fn foo<'a>(x: &'a i32, y: &i32) -> &'a i32`
-    // Here, we would return the hir::Param for y, we return the type &'a
-    // i32, which is the type of y but with the anonymous region replaced
-    // with 'a, the corresponding bound region and is_first which is true if
-    // the hir::Param is the first parameter in the function declaration.
     pub(super) fn find_param_with_region(
         &self,
         anon_region: Region<'tcx>,
         replace_region: Region<'tcx>,
     ) -> Option<AnonymousParamInfo<'_>> {
-        let (id, bound_region) = match *anon_region {
-            ty::ReFree(ref free_region) => (free_region.scope, free_region.bound_region),
-            ty::ReEarlyBound(ebr) => (
-                self.tcx().parent(ebr.def_id).unwrap(),
-                ty::BoundRegionKind::BrNamed(ebr.def_id, ebr.name),
-            ),
-            _ => return None, // not a free region
-        };
-
-        let hir = &self.tcx().hir();
-        let hir_id = hir.local_def_id_to_hir_id(id.as_local()?);
-        let body_id = hir.maybe_body_owned_by(hir_id)?;
-        let body = hir.body(body_id);
-        let owner_id = hir.body_owner(body_id);
-        let fn_decl = hir.fn_decl_by_hir_id(owner_id).unwrap();
-        let poly_fn_sig = self.tcx().fn_sig(id);
-        let fn_sig = self.tcx().liberate_late_bound_regions(id, poly_fn_sig);
-        body.params
-            .iter()
-            .take(if fn_sig.c_variadic {
-                fn_sig.inputs().len()
-            } else {
-                assert_eq!(fn_sig.inputs().len(), body.params.len());
-                body.params.len()
-            })
-            .enumerate()
-            .find_map(|(index, param)| {
-                // May return None; sometimes the tables are not yet populated.
-                let ty = fn_sig.inputs()[index];
-                let mut found_anon_region = false;
-                let new_param_ty = self.tcx().fold_regions(ty, &mut false, |r, _| {
-                    if r == anon_region {
-                        found_anon_region = true;
-                        replace_region
-                    } else {
-                        r
-                    }
-                });
-                if found_anon_region {
-                    let ty_hir_id = fn_decl.inputs[index].hir_id;
-                    let param_ty_span = hir.span(ty_hir_id);
-                    let is_first = index == 0;
-                    Some(AnonymousParamInfo {
-                        param,
-                        param_ty: new_param_ty,
-                        param_ty_span,
-                        bound_region,
-                        is_first,
-                    })
-                } else {
-                    None
-                }
-            })
+        find_param_with_region(self.tcx(), anon_region, replace_region)
     }
 
     // Here, we check for the case where the anonymous region

compiler/rustc_typeck/src/astconv/mod.rs

@@ -2681,21 +2681,21 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
         let trait_ref =
             self.instantiate_mono_trait_ref(i.of_trait.as_ref()?, self.ast_ty_to_ty(i.self_ty));
 
-        let x: &ty::AssocItem = tcx.associated_items(trait_ref.def_id).find_by_name_and_kind(
+        let assoc = tcx.associated_items(trait_ref.def_id).find_by_name_and_kind(
             tcx,
             *ident,
             ty::AssocKind::Fn,
             trait_ref.def_id,
         )?;
 
-        let fn_sig = tcx.fn_sig(x.def_id).subst(
+        let fn_sig = tcx.fn_sig(assoc.def_id).subst(
             tcx,
-            trait_ref.substs.extend_to(tcx, x.def_id, |param, _| tcx.mk_param_from_def(param)),
+            trait_ref.substs.extend_to(tcx, assoc.def_id, |param, _| tcx.mk_param_from_def(param)),
         );
 
         let ty = if let Some(arg_idx) = arg_idx { fn_sig.input(arg_idx) } else { fn_sig.output() };
 
-        Some(tcx.erase_late_bound_regions(ty))
+        Some(tcx.liberate_late_bound_regions(fn_hir_id.expect_owner().to_def_id(), ty))
     }
 
     fn validate_late_bound_regions(