A few small cleanups for newtype_index

Remove the `..` from the body, only a few invocations used it and it's
inconsistent with rust syntax.

Use `;` instead of `,` between consts. As the Rust syntax gods inteded.

compiler/rustc_span/src/def_id.rs

@@ -12,8 +12,7 @@ use std::hash::{Hash, Hasher};
 rustc_index::newtype_index! {
     #[custom_encodable]
     #[debug_format = "crate{}"]
-    pub struct CrateNum {
-    }
+    pub struct CrateNum {}
 }
 
 /// Item definitions in the currently-compiled crate would have the `CrateNum`
@@ -199,7 +198,7 @@ rustc_index::newtype_index! {
     pub struct DefIndex {
         /// The crate root is always assigned index 0 by the AST Map code,
         /// thanks to `NodeCollector::new`.
-        const CRATE_DEF_INDEX = 0,
+        const CRATE_DEF_INDEX = 0;
     }
 }
 

compiler/rustc_span/src/hygiene.rs

@@ -62,8 +62,7 @@ pub struct SyntaxContextData {
 rustc_index::newtype_index! {
     /// A unique ID associated with a macro invocation and expansion.
     #[custom_encodable]
-    pub struct ExpnIndex {
-    }
+    pub struct ExpnIndex {}
 }
 
 /// A unique ID associated with a macro invocation and expansion.
@@ -85,8 +84,7 @@ rustc_index::newtype_index! {
     #[custom_encodable]
     #[no_ord_impl]
     #[debug_format = "expn{}"]
-    pub struct LocalExpnId {
-    }
+    pub struct LocalExpnId {}
 }
 
 // To ensure correctness of incremental compilation,

compiler/rustc_span/src/symbol.rs

@@ -1801,7 +1801,7 @@ impl fmt::Display for MacroRulesNormalizedIdent {
 pub struct Symbol(SymbolIndex);
 
 rustc_index::newtype_index! {
-    struct SymbolIndex { .. }
+    struct SymbolIndex {}
 }
 
 impl Symbol {