Provide copy-free access to raw Decoder bytes

2 files changed, 7 insertions, 14 deletions

diff --git a/compiler/rustc_serialize/src/opaque.rs b/compiler/rustc_serialize/src/opaque.rs
index 8e2c866cd38..1a71ee9038b 100644
--- a/compiler/rustc_serialize/src/opaque.rs
+++ b/compiler/rustc_serialize/src/opaque.rs
@@ -1,5 +1,5 @@
 use crate::leb128::{self, max_leb128_len};
-use crate::serialize::{self, Encoder as _};
+use crate::serialize::{self, Decoder as _, Encoder as _};
 use std::convert::TryInto;
 use std::fs::File;
 use std::io::{self, Write};
@@ -548,13 +548,6 @@ impl<'a> Decoder<'a> {
     pub fn advance(&mut self, bytes: usize) {
         self.position += bytes;
     }
-
-    #[inline]
-    pub fn read_raw_bytes(&mut self, bytes: usize) -> &'a [u8] {
-        let start = self.position;
-        self.position += bytes;
-        &self.data[start..self.position]
-    }
 }
 
 macro_rules! read_leb128 {
@@ -662,7 +655,7 @@ impl<'a> serialize::Decoder for Decoder<'a> {
     }
 
     #[inline]
-    fn read_str(&mut self) -> &str {
+    fn read_str(&mut self) -> &'a str {
         let len = self.read_usize();
         let sentinel = self.data[self.position + len];
         assert!(sentinel == STR_SENTINEL);
@@ -674,10 +667,10 @@ impl<'a> serialize::Decoder for Decoder<'a> {
     }
 
     #[inline]
-    fn read_raw_bytes_into(&mut self, s: &mut [u8]) {
+    fn read_raw_bytes(&mut self, bytes: usize) -> &'a [u8] {
         let start = self.position;
-        self.position += s.len();
-        s.copy_from_slice(&self.data[start..self.position]);
+        self.position += bytes;
+        &self.data[start..self.position]
     }
 }
 
@@ -745,10 +738,10 @@ impl<'a> serialize::Decodable<Decoder<'a>> for IntEncodedWithFixedSize {
     fn decode(decoder: &mut Decoder<'a>) -> IntEncodedWithFixedSize {
         let _start_pos = decoder.position();
         let bytes = decoder.read_raw_bytes(IntEncodedWithFixedSize::ENCODED_SIZE);
+        let value = u64::from_le_bytes(bytes.try_into().unwrap());
         let _end_pos = decoder.position();
         debug_assert_eq!((_end_pos - _start_pos), IntEncodedWithFixedSize::ENCODED_SIZE);
 
-        let value = u64::from_le_bytes(bytes.try_into().unwrap());
         IntEncodedWithFixedSize(value)
     }
 }
diff --git a/compiler/rustc_serialize/src/serialize.rs b/compiler/rustc_serialize/src/serialize.rs
index fbbd13657ba..7b6dd8b60f8 100644
--- a/compiler/rustc_serialize/src/serialize.rs
+++ b/compiler/rustc_serialize/src/serialize.rs
@@ -199,7 +199,7 @@ pub trait Decoder {
     fn read_f32(&mut self) -> f32;
     fn read_char(&mut self) -> char;
     fn read_str(&mut self) -> &str;
-    fn read_raw_bytes_into(&mut self, s: &mut [u8]);
+    fn read_raw_bytes(&mut self, len: usize) -> &[u8];
 }
 
 /// Trait for types that can be serialized