rustdoc: Delete `ReceiverTy` (formerly known as `SelfTy`)

It was barely used, and the places that used it are actually clearer
without it since they were often undoing some of its work. This also
avoids an unnecessary clone of the receiver type and removes a layer of
logical indirection in the code.

3 files changed, 18 insertions, 45 deletions

diff --git a/src/librustdoc/clean/types.rs b/src/librustdoc/clean/types.rs
index 82f1312364a..4850500a1bf 100644
--- a/src/librustdoc/clean/types.rs
+++ b/src/librustdoc/clean/types.rs
@@ -34,7 +34,6 @@ use thin_vec::ThinVec;
 use {rustc_ast as ast, rustc_hir as hir};
 
 pub(crate) use self::ItemKind::*;
-pub(crate) use self::ReceiverTy::*;
 pub(crate) use self::Type::{
     Array, BareFunction, BorrowedRef, DynTrait, Generic, ImplTrait, Infer, Primitive, QPath,
     RawPointer, SelfTy, Slice, Tuple,
@@ -1384,7 +1383,7 @@ pub(crate) struct FnDecl {
 }
 
 impl FnDecl {
-    pub(crate) fn receiver_type(&self) -> Option<ReceiverTy> {
+    pub(crate) fn receiver_type(&self) -> Option<&Type> {
         self.inputs.values.get(0).and_then(|v| v.to_receiver())
     }
 }
@@ -1403,27 +1402,9 @@ pub(crate) struct Argument {
     pub(crate) is_const: bool,
 }
 
-#[derive(Clone, PartialEq, Debug)]
-pub(crate) enum ReceiverTy {
-    SelfValue,
-    SelfBorrowed(Option<Lifetime>, Mutability),
-    SelfExplicit(Type),
-}
-
 impl Argument {
-    pub(crate) fn to_receiver(&self) -> Option<ReceiverTy> {
-        if self.name != kw::SelfLower {
-            return None;
-        }
-        if self.type_.is_self_type() {
-            return Some(SelfValue);
-        }
-        match self.type_ {
-            BorrowedRef { ref lifetime, mutability, ref type_ } if type_.is_self_type() => {
-                Some(SelfBorrowed(lifetime.clone(), mutability))
-            }
-            _ => Some(SelfExplicit(self.type_.clone())),
-        }
+    pub(crate) fn to_receiver(&self) -> Option<&Type> {
+        if self.name == kw::SelfLower { Some(&self.type_) } else { None }
     }
 }
 
diff --git a/src/librustdoc/html/format.rs b/src/librustdoc/html/format.rs
index 0fe535ade9b..b5ab6a35fdb 100644
--- a/src/librustdoc/html/format.rs
+++ b/src/librustdoc/html/format.rs
@@ -1455,27 +1455,20 @@ impl clean::FnDecl {
         for (i, input) in self.inputs.values.iter().enumerate() {
             if let Some(selfty) = input.to_receiver() {
                 match selfty {
-                    clean::SelfValue => {
+                    clean::SelfTy => {
                         write!(f, "self")?;
                     }
-                    clean::SelfBorrowed(Some(ref lt), mutability) => {
-                        write!(
-                            f,
-                            "{amp}{lifetime} {mutability}self",
-                            lifetime = lt.print(),
-                            mutability = mutability.print_with_space(),
-                        )?;
-                    }
-                    clean::SelfBorrowed(None, mutability) => {
-                        write!(
-                            f,
-                            "{amp}{mutability}self",
-                            mutability = mutability.print_with_space(),
-                        )?;
+                    clean::BorrowedRef { lifetime, mutability, type_: box clean::SelfTy } => {
+                        write!(f, "{amp}")?;
+                        match lifetime {
+                            Some(lt) => write!(f, "{lt} ", lt = lt.print())?,
+                            None => {}
+                        }
+                        write!(f, "{mutability}self", mutability = mutability.print_with_space())?;
                     }
-                    clean::SelfExplicit(ref typ) => {
+                    _ => {
                         write!(f, "self: ")?;
-                        typ.print(cx).fmt(f)?;
+                        selfty.print(cx).fmt(f)?;
                     }
                 }
             } else {
diff --git a/src/librustdoc/html/render/mod.rs b/src/librustdoc/html/render/mod.rs
index b7bcda2a604..9074e40a536 100644
--- a/src/librustdoc/html/render/mod.rs
+++ b/src/librustdoc/html/render/mod.rs
@@ -58,7 +58,7 @@ use serde::{Serialize, Serializer};
 
 pub(crate) use self::context::*;
 pub(crate) use self::span_map::{collect_spans_and_sources, LinkFromSrc};
-use crate::clean::{self, ItemId, ReceiverTy, RenderedLink};
+use crate::clean::{self, ItemId, RenderedLink};
 use crate::error::Error;
 use crate::formats::cache::Cache;
 use crate::formats::item_type::ItemType;
@@ -1378,15 +1378,14 @@ fn should_render_item(item: &clean::Item, deref_mut_: bool, tcx: TyCtxt<'_>) ->
     };
 
     if let Some(self_ty) = self_type_opt {
-        let (by_mut_ref, by_box, by_value) = match self_ty {
-            ReceiverTy::SelfBorrowed(_, mutability)
-            | ReceiverTy::SelfExplicit(clean::BorrowedRef { mutability, .. }) => {
+        let (by_mut_ref, by_box, by_value) = match *self_ty {
+            clean::Type::BorrowedRef { mutability, .. } => {
                 (mutability == Mutability::Mut, false, false)
             }
-            ReceiverTy::SelfExplicit(clean::Type::Path { path }) => {
+            clean::Type::Path { ref path } => {
                 (false, Some(path.def_id()) == tcx.lang_items().owned_box(), false)
             }
-            ReceiverTy::SelfValue => (false, false, true),
+            clean::Type::SelfTy => (false, false, true),
             _ => (false, false, false),
         };