Remove now-obsolete visit_pattern_type_pattern

compiler/rustc_ast_lowering/src/index.rs

@@ -393,10 +393,6 @@ impl<'a, 'hir> Visitor<'hir> for NodeCollector<'a, 'hir> {
         });
     }
 
-    fn visit_pattern_type_pattern(&mut self, p: &'hir hir::Pat<'hir>) {
-        self.visit_pat(p)
-    }
-
     fn visit_precise_capturing_arg(
         &mut self,
         arg: &'hir PreciseCapturingArg<'hir>,

compiler/rustc_hir/src/intravisit.rs

@@ -364,11 +364,6 @@ pub trait Visitor<'v>: Sized {
     fn visit_ty(&mut self, t: &'v Ty<'v>) -> Self::Result {
         walk_ty(self, t)
     }
-    fn visit_pattern_type_pattern(&mut self, _p: &'v Pat<'v>) {
-        // Do nothing. Only a few visitors need to know the details of the pattern type,
-        // and they opt into it. All other visitors will just choke on our fake patterns
-        // because they aren't in a body.
-    }
     fn visit_generic_param(&mut self, p: &'v GenericParam<'v>) -> Self::Result {
         walk_generic_param(self, p)
     }
@@ -918,7 +913,7 @@ pub fn walk_ty<'v, V: Visitor<'v>>(visitor: &mut V, typ: &'v Ty<'v>) -> V::Resul
         }
         TyKind::Pat(ty, pat) => {
             try_visit!(visitor.visit_ty(ty));
-            try_visit!(visitor.visit_pattern_type_pattern(pat));
+            try_visit!(visitor.visit_pat(pat));
         }
     }
     V::Result::output()

compiler/rustc_hir_analysis/src/collect/resolve_bound_vars.rs

@@ -826,11 +826,6 @@ impl<'a, 'tcx> Visitor<'tcx> for BoundVarContext<'a, 'tcx> {
         }
     }
 
-    #[instrument(level = "debug", skip(self))]
-    fn visit_pattern_type_pattern(&mut self, p: &'tcx hir::Pat<'tcx>) {
-        intravisit::walk_pat(self, p)
-    }
-
     #[instrument(level = "debug", skip(self))]
     fn visit_trait_item(&mut self, trait_item: &'tcx hir::TraitItem<'tcx>) {
         use self::hir::TraitItemKind::*;

compiler/rustc_passes/src/hir_id_validator.rs

@@ -161,8 +161,4 @@ impl<'a, 'hir> intravisit::Visitor<'hir> for HirIdValidator<'a, 'hir> {
         let mut inner_visitor = self.new_visitor(self.tcx);
         inner_visitor.check(i.owner_id, |this| intravisit::walk_impl_item(this, i));
     }
-
-    fn visit_pattern_type_pattern(&mut self, p: &'hir hir::Pat<'hir>) {
-        self.visit_pat(p)
-    }
 }

tests/ui/type/pattern_types/bad_const_generics_args_on_const_param.rs

@@ -6,5 +6,6 @@ type Pat<const START: u32, const END: u32> =
 //~^ ERROR type and const arguments are not allowed on const parameter `START`
 //~| ERROR type arguments are not allowed on const parameter `END`
 //~| ERROR associated item constraints are not allowed here
+//~| ERROR the placeholder `_` is not allowed within types on item signatures
 
 fn main() {}

tests/ui/type/pattern_types/bad_const_generics_args_on_const_param.stderr

@@ -32,7 +32,13 @@ error[E0229]: associated item constraints are not allowed here
 LL |     std::pat::pattern_type!(u32 is START::<(), i32, 2>..=END::<_, Assoc = ()>);
    |                                                                   ^^^^^^^^^^ associated item constraint not allowed here
 
-error: aborting due to 3 previous errors
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for type aliases
+  --> $DIR/bad_const_generics_args_on_const_param.rs:5:64
+   |
+LL |     std::pat::pattern_type!(u32 is START::<(), i32, 2>..=END::<_, Assoc = ()>);
+   |                                                                ^ not allowed in type signatures
+
+error: aborting due to 4 previous errors
 
-Some errors have detailed explanations: E0109, E0229.
+Some errors have detailed explanations: E0109, E0121, E0229.
 For more information about an error, try `rustc --explain E0109`.