rebase

Author: lcnr

compiler/rustc_ast_lowering/src/lib.rs

@@ -523,13 +523,6 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                     _ => visit::walk_ty(self, t),
                 }
             }
-
-            fn visit_anon_const(&mut self, ct: &'tcx AnonConst) {
-                self.lctx.allocate_hir_id_counter(ct.id);
-                self.with_hir_id_owner(Some(ct.id), |this| {
-                    visit::walk_anon_const(this, ct);
-                });
-            }
         }
 
         self.lower_node_id(CRATE_NODE_ID);
@@ -2401,7 +2394,11 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                         })
                     }));
 
-                hir::AnonConst {
+                // The generics of an anonymous constants refer to the
+                // generics of their parent anon const, so we only have to
+                // deal with each higher ranked lifetime at the outermost const.
+                let hrtb_start = mem::replace(&mut this.hrtb_start, None);
+                let ct = hir::AnonConst {
                     hir_id,
                     generics: hir::Generics {
                         params: generic_params,
@@ -2414,7 +2411,9 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                         parenthesized: false,
                     },
                     body: this.lower_const_body(c.value.span, Some(&c.value)),
-                }
+                };
+                this.hrtb_start = hrtb_start;
+                ct
             })
         })
     }

compiler/rustc_resolve/src/late/lifetimes.rs

@@ -1577,12 +1577,8 @@ impl<'a, 'tcx> LifetimeContext<'a, 'tcx> {
     }
 
     fn check_uses_for_lifetimes_defined_by_scope(&mut self) {
-        let defined_by = match self.scope {
-            Scope::Binder { from_anon_const: true, .. } => {
-                debug!("check_uses_for_lifetimes_defined_by_scope: synthetic anon const binder");
-                return;
-            }
-            Scope::Binder { lifetimes, .. } => lifetimes,
+        let (defined_by, from_anon_const) = match self.scope {
+            &Scope::Binder { ref lifetimes, from_anon_const, .. } => (lifetimes, from_anon_const),
             _ => {
                 debug!("check_uses_for_lifetimes_defined_by_scope: not in a binder scope");
                 return;
@@ -1600,6 +1596,14 @@ impl<'a, 'tcx> LifetimeContext<'a, 'tcx> {
             })
             .collect();
 
+        if from_anon_const {
+            debug!("check_uses_for_lifetimes_defined_by_scope: synthetic anon const");
+            for def_id in def_ids {
+                self.lifetime_uses.remove(&def_id);
+            }
+            return;
+        }
+
         // ensure that we issue lints in a repeatable order
         def_ids.sort_by_cached_key(|&def_id| self.tcx.def_path_hash(def_id));
 

src/test/ui/associated-item/associated-item-duplicate-bounds.stderr

@@ -5,6 +5,7 @@ LL |     links: [u32; A::LINKS],
    |                  ^^^^^^^^ cannot perform const operation using `A`
    |
    = note: type parameters may not be used in const expressions
+   = help: use `#![feature(const_generics)]` and `#![feature(const_evaluatable_checked)]` to allow generic const expressions
 
 error: aborting due to previous error
 

src/test/ui/issues/issue-39559.stderr

@@ -5,6 +5,7 @@ LL |     entries: [T; D::dim()],
    |                  ^^^^^^ cannot perform const operation using `D`
    |
    = note: type parameters may not be used in const expressions
+   = help: use `#![feature(const_generics)]` and `#![feature(const_evaluatable_checked)]` to allow generic const expressions
 
 error: aborting due to previous error