Remove emit_unit

It doesn't do anything for all encoders

compiler/rustc_ast/src/ast.rs

@@ -2473,8 +2473,8 @@ rustc_index::newtype_index! {
 }
 
 impl<S: Encoder> rustc_serialize::Encodable<S> for AttrId {
-    fn encode(&self, s: &mut S) -> Result<(), S::Error> {
-        s.emit_unit()
+    fn encode(&self, _s: &mut S) -> Result<(), S::Error> {
+        Ok(())
     }
 }
 

compiler/rustc_metadata/src/rmeta/encoder.rs

@@ -95,11 +95,6 @@ macro_rules! encoder_methods {
 impl<'a, 'tcx> Encoder for EncodeContext<'a, 'tcx> {
     type Error = <opaque::Encoder as Encoder>::Error;
 
-    #[inline]
-    fn emit_unit(&mut self) -> Result<(), Self::Error> {
-        Ok(())
-    }
-
     encoder_methods! {
         emit_usize(usize);
         emit_u128(u128);

compiler/rustc_middle/src/mir/predecessors.rs

@@ -56,8 +56,8 @@ impl PredecessorCache {
 
 impl<S: serialize::Encoder> serialize::Encodable<S> for PredecessorCache {
     #[inline]
-    fn encode(&self, s: &mut S) -> Result<(), S::Error> {
-        s.emit_unit()
+    fn encode(&self, _s: &mut S) -> Result<(), S::Error> {
+        Ok(())
     }
 }
 

compiler/rustc_middle/src/mir/switch_sources.rs

@@ -56,8 +56,8 @@ impl SwitchSourceCache {
 
 impl<S: serialize::Encoder> serialize::Encodable<S> for SwitchSourceCache {
     #[inline]
-    fn encode(&self, s: &mut S) -> Result<(), S::Error> {
-        s.emit_unit()
+    fn encode(&self, _s: &mut S) -> Result<(), S::Error> {
+        Ok(())
     }
 }
 

compiler/rustc_middle/src/mir/traversal.rs

@@ -367,8 +367,8 @@ impl PostorderCache {
 
 impl<S: serialize::Encoder> serialize::Encodable<S> for PostorderCache {
     #[inline]
-    fn encode(&self, s: &mut S) -> Result<(), S::Error> {
-        s.emit_unit()
+    fn encode(&self, _s: &mut S) -> Result<(), S::Error> {
+        Ok(())
     }
 }
 

compiler/rustc_query_impl/src/on_disk_cache.rs

@@ -993,11 +993,6 @@ where
 {
     type Error = E::Error;
 
-    #[inline]
-    fn emit_unit(&mut self) -> Result<(), Self::Error> {
-        Ok(())
-    }
-
     encoder_methods! {
         emit_usize(usize);
         emit_u128(u128);

compiler/rustc_serialize/src/opaque.rs

@@ -64,11 +64,6 @@ const STR_SENTINEL: u8 = 0xC1;
 impl serialize::Encoder for Encoder {
     type Error = !;
 
-    #[inline]
-    fn emit_unit(&mut self) -> EncodeResult {
-        Ok(())
-    }
-
     #[inline]
     fn emit_usize(&mut self, v: usize) -> EncodeResult {
         write_leb128!(self, v, usize, write_usize_leb128)
@@ -419,11 +414,6 @@ macro_rules! file_encoder_write_leb128 {
 impl serialize::Encoder for FileEncoder {
     type Error = io::Error;
 
-    #[inline]
-    fn emit_unit(&mut self) -> FileEncodeResult {
-        Ok(())
-    }
-
     #[inline]
     fn emit_usize(&mut self, v: usize) -> FileEncodeResult {
         file_encoder_write_leb128!(self, v, usize, write_usize_leb128)

compiler/rustc_serialize/src/serialize.rs

@@ -15,7 +15,6 @@ pub trait Encoder {
     type Error;
 
     // Primitive types:
-    fn emit_unit(&mut self) -> Result<(), Self::Error>;
     fn emit_usize(&mut self, v: usize) -> Result<(), Self::Error>;
     fn emit_u128(&mut self, v: u128) -> Result<(), Self::Error>;
     fn emit_u64(&mut self, v: u64) -> Result<(), Self::Error>;
@@ -203,8 +202,8 @@ impl<D: Decoder> Decodable<D> for String {
 }
 
 impl<S: Encoder> Encodable<S> for () {
-    fn encode(&self, s: &mut S) -> Result<(), S::Error> {
-        s.emit_unit()
+    fn encode(&self, _s: &mut S) -> Result<(), S::Error> {
+        Ok(())
     }
 }
 
@@ -213,8 +212,8 @@ impl<D: Decoder> Decodable<D> for () {
 }
 
 impl<S: Encoder, T> Encodable<S> for PhantomData<T> {
-    fn encode(&self, s: &mut S) -> Result<(), S::Error> {
-        s.emit_unit()
+    fn encode(&self, _s: &mut S) -> Result<(), S::Error> {
+        Ok(())
     }
 }