compiler: rename {ast,hir}::BareFn* to FnPtr*

Fix some comments and related types and locals where it is obvious, e.g.
- bare_fn -> fn_ptr
- LifetimeBinderKind::BareFnType -> LifetimeBinderKind::FnPtrType

Co-authored-by: León Orell Valerian Liehr <me@fmease.dev>

compiler/rustc_hir/src/def.rs

@@ -831,7 +831,7 @@ pub enum LifetimeRes {
         /// Id of the introducing place. That can be:
         /// - an item's id, for the item's generic parameters;
         /// - a TraitRef's ref_id, identifying the `for<...>` binder;
-        /// - a BareFn type's id.
+        /// - a FnPtr type's id.
         ///
         /// This information is used for impl-trait lifetime captures, to know when to or not to
         /// capture any given lifetime.

compiler/rustc_hir/src/hir.rs

@@ -3526,7 +3526,7 @@ impl PrimTy {
 }
 
 #[derive(Debug, Clone, Copy, HashStable_Generic)]
-pub struct BareFnTy<'hir> {
+pub struct FnPtrTy<'hir> {
     pub safety: Safety,
     pub abi: ExternAbi,
     pub generic_params: &'hir [GenericParam<'hir>],
@@ -3645,8 +3645,8 @@ pub enum TyKind<'hir, Unambig = ()> {
     Ptr(MutTy<'hir>),
     /// A reference (i.e., `&'a T` or `&'a mut T`).
     Ref(&'hir Lifetime, MutTy<'hir>),
-    /// A bare function (e.g., `fn(usize) -> bool`).
-    BareFn(&'hir BareFnTy<'hir>),
+    /// A function pointer (e.g., `fn(usize) -> bool`).
+    FnPtr(&'hir FnPtrTy<'hir>),
     /// An unsafe binder type (e.g. `unsafe<'a> Foo<'a>`).
     UnsafeBinder(&'hir UnsafeBinderTy<'hir>),
     /// The never type (`!`).
@@ -4498,7 +4498,7 @@ pub enum ForeignItemKind<'hir> {
     ///
     /// All argument idents are actually always present (i.e. `Some`), but
     /// `&[Option<Ident>]` is used because of code paths shared with `TraitFn`
-    /// and `BareFnTy`. The sharing is due to all of these cases not allowing
+    /// and `FnPtrTy`. The sharing is due to all of these cases not allowing
     /// arbitrary patterns for parameters.
     Fn(FnSig<'hir>, &'hir [Option<Ident>], &'hir Generics<'hir>),
     /// A foreign static item (`static ext: u8`).

compiler/rustc_hir/src/intravisit.rs

@@ -1001,7 +1001,7 @@ pub fn walk_ty<'v, V: Visitor<'v>>(visitor: &mut V, typ: &'v Ty<'v, AmbigArg>) -
         TyKind::Tup(tuple_element_types) => {
             walk_list!(visitor, visit_ty_unambig, tuple_element_types);
         }
-        TyKind::BareFn(ref function_declaration) => {
+        TyKind::FnPtr(ref function_declaration) => {
             walk_list!(visitor, visit_generic_param, function_declaration.generic_params);
             try_visit!(visitor.visit_fn_decl(function_declaration.decl));
         }