Merging upstream version 1.72.1+dfsg1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 63 insertions, 10 deletions

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 794812a5c..acd0bcd8e 100644
--- a/compiler/rustc_hir_analysis/src/collect/resolve_bound_vars.rs
+++ b/compiler/rustc_hir_analysis/src/collect/resolve_bound_vars.rs
@@ -22,7 +22,7 @@ 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;
+use rustc_span::{Span, DUMMY_SP};
 use std::fmt;
 
 use crate::errors;
@@ -338,7 +338,17 @@ impl<'a, 'tcx> BoundVarContext<'a, 'tcx> {
 
                 Scope::TraitRefBoundary { .. } => {
                     // We should only see super trait lifetimes if there is a `Binder` above
-                    assert!(supertrait_bound_vars.is_empty());
+                    // though this may happen when we call `poly_trait_ref_binder_info` with
+                    // an (erroneous, #113423) associated return type bound in an impl header.
+                    if !supertrait_bound_vars.is_empty() {
+                        self.tcx.sess.delay_span_bug(
+                            DUMMY_SP,
+                            format!(
+                                "found supertrait lifetimes without a binder to append \
+                                them to: {supertrait_bound_vars:?}"
+                            ),
+                        );
+                    }
                     break (vec![], BinderScopeType::Normal);
                 }
 
@@ -556,7 +566,7 @@ impl<'a, 'tcx> Visitor<'tcx> for BoundVarContext<'a, 'tcx> {
                     });
                 }
             }
-            hir::ItemKind::OpaqueTy(hir::OpaqueTy {
+            hir::ItemKind::OpaqueTy(&hir::OpaqueTy {
                 origin: hir::OpaqueTyOrigin::FnReturn(parent) | hir::OpaqueTyOrigin::AsyncFn(parent),
                 generics,
                 ..
@@ -1344,12 +1354,10 @@ impl<'a, 'tcx> BoundVarContext<'a, 'tcx> {
                 Scope::Binder {
                     where_bound_origin: Some(hir::PredicateOrigin::ImplTrait), ..
                 } => {
-                    let mut err = self.tcx.sess.struct_span_err(
-                        lifetime_ref.ident.span,
-                        "`impl Trait` can only mention lifetimes bound at the fn or impl level",
-                    );
-                    err.span_note(self.tcx.def_span(region_def_id), "lifetime declared here");
-                    err.emit();
+                    self.tcx.sess.emit_err(errors::LateBoundInApit::Lifetime {
+                        span: lifetime_ref.ident.span,
+                        param_span: self.tcx.def_span(region_def_id),
+                    });
                     return;
                 }
                 Scope::Root { .. } => break,
@@ -1379,6 +1387,7 @@ impl<'a, 'tcx> BoundVarContext<'a, 'tcx> {
         let mut late_depth = 0;
         let mut scope = self.scope;
         let mut crossed_anon_const = false;
+
         let result = loop {
             match *scope {
                 Scope::Body { s, .. } => {
@@ -1446,6 +1455,50 @@ impl<'a, 'tcx> BoundVarContext<'a, 'tcx> {
             return;
         }
 
+        // We may fail to resolve higher-ranked ty/const vars that are mentioned by APIT.
+        // AST-based resolution does not care for impl-trait desugaring, which are the
+        // responsibility of lowering. This may create a mismatch between the resolution
+        // AST found (`param_def_id`) which points to HRTB, and what HIR allows.
+        // ```
+        // fn foo(x: impl for<T> Trait<Assoc = impl Trait2<T>>) {}
+        // ```
+        //
+        // In such case, walk back the binders to diagnose it properly.
+        let mut scope = self.scope;
+        loop {
+            match *scope {
+                Scope::Binder {
+                    where_bound_origin: Some(hir::PredicateOrigin::ImplTrait), ..
+                } => {
+                    let guar = self.tcx.sess.emit_err(match self.tcx.def_kind(param_def_id) {
+                        DefKind::TyParam => errors::LateBoundInApit::Type {
+                            span: self.tcx.hir().span(hir_id),
+                            param_span: self.tcx.def_span(param_def_id),
+                        },
+                        DefKind::ConstParam => errors::LateBoundInApit::Const {
+                            span: self.tcx.hir().span(hir_id),
+                            param_span: self.tcx.def_span(param_def_id),
+                        },
+                        kind => {
+                            bug!("unexpected def-kind: {}", kind.descr(param_def_id.to_def_id()))
+                        }
+                    });
+                    self.map.defs.insert(hir_id, ResolvedArg::Error(guar));
+                    return;
+                }
+                Scope::Root { .. } => break,
+                Scope::Binder { s, .. }
+                | Scope::Body { s, .. }
+                | Scope::Elision { s, .. }
+                | Scope::ObjectLifetimeDefault { s, .. }
+                | Scope::Supertrait { s, .. }
+                | Scope::TraitRefBoundary { s, .. }
+                | Scope::AnonConstBoundary { s } => {
+                    scope = s;
+                }
+            }
+        }
+
         self.tcx.sess.delay_span_bug(
             self.tcx.hir().span(hir_id),
             format!("could not resolve {param_def_id:?}"),
@@ -1761,7 +1814,7 @@ impl<'a, 'tcx> BoundVarContext<'a, 'tcx> {
             let obligations = predicates.predicates.iter().filter_map(|&(pred, _)| {
                 let bound_predicate = pred.kind();
                 match bound_predicate.skip_binder() {
-                    ty::PredicateKind::Clause(ty::Clause::Trait(data)) => {
+                    ty::ClauseKind::Trait(data) => {
                         // The order here needs to match what we would get from `subst_supertrait`
                         let pred_bound_vars = bound_predicate.bound_vars();
                         let mut all_bound_vars = bound_vars.clone();