Rollup merge of rust-lang#65824 - eddyb:def-key-copy, r=varkor

rustc: make DefPathData (and friends) Copy (now that it uses Symbol).

Spotted this while working on something else.

src/librustc/hir/map/definitions.rs

@@ -53,7 +53,7 @@ impl DefPathTable {
 
     #[inline(always)]
     pub fn def_key(&self, index: DefIndex) -> DefKey {
-        self.index_to_key[index.index()].clone()
+        self.index_to_key[index.index()]
     }
 
     #[inline(always)]
@@ -111,7 +111,7 @@ pub struct Definitions {
 /// A unique identifier that we can use to lookup a definition
 /// precisely. It combines the index of the definition's parent (if
 /// any) with a `DisambiguatedDefPathData`.
-#[derive(Clone, PartialEq, Debug, RustcEncodable, RustcDecodable)]
+#[derive(Copy, Clone, PartialEq, Debug, RustcEncodable, RustcDecodable)]
 pub struct DefKey {
     /// The parent path.
     pub parent: Option<DefIndex>,
@@ -164,7 +164,7 @@ impl DefKey {
 /// between them. This introduces some artificial ordering dependency
 /// but means that if you have, e.g., two impls for the same type in
 /// the same module, they do get distinct `DefId`s.
-#[derive(Clone, PartialEq, Debug, RustcEncodable, RustcDecodable)]
+#[derive(Copy, Clone, PartialEq, Debug, RustcEncodable, RustcDecodable)]
 pub struct DisambiguatedDefPathData {
     pub data: DefPathData,
     pub disambiguator: u32
@@ -277,7 +277,7 @@ impl DefPath {
     }
 }
 
-#[derive(Clone, Debug, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
+#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
 pub enum DefPathData {
     // Root: these should only be used for the root nodes, because
     // they are treated specially by the `def_path` function.
@@ -359,7 +359,7 @@ impl Definitions {
 
     #[inline]
     pub fn opt_def_index(&self, node: ast::NodeId) -> Option<DefIndex> {
-        self.node_to_def_index.get(&node).cloned()
+        self.node_to_def_index.get(&node).copied()
     }
 
     #[inline]
@@ -413,7 +413,7 @@ impl Definitions {
     #[inline]
     pub fn opt_span(&self, def_id: DefId) -> Option<Span> {
         if def_id.krate == LOCAL_CRATE {
-            self.def_index_to_span.get(&def_id.index).cloned()
+            self.def_index_to_span.get(&def_id.index).copied()
         } else {
             None
         }
@@ -472,7 +472,7 @@ impl Definitions {
 
         // Find the next free disambiguator for this key.
         let disambiguator = {
-            let next_disamb = self.next_disambiguator.entry((parent, data.clone())).or_insert(0);
+            let next_disamb = self.next_disambiguator.entry((parent, data)).or_insert(0);
             let disambiguator = *next_disamb;
             *next_disamb = next_disamb.checked_add(1).expect("disambiguator overflow");
             disambiguator
@@ -525,7 +525,7 @@ impl Definitions {
     }
 
     pub fn expansion_that_defined(&self, index: DefIndex) -> ExpnId {
-        self.expansions_that_defined.get(&index).cloned().unwrap_or(ExpnId::root())
+        self.expansions_that_defined.get(&index).copied().unwrap_or(ExpnId::root())
     }
 
     pub fn parent_module_of_macro_def(&self, expn_id: ExpnId) -> DefId {