rustc_metadata: use decoder::Metadata instead of &[u8] for Lazy<Table<T>>::get.

Author: eddyb

src/librustc_metadata/decoder.rs

@@ -132,8 +132,8 @@ impl<'a, 'tcx> Metadata<'a, 'tcx> for (&'a CrateMetadata, TyCtxt<'tcx>) {
 }
 
 impl<'a, 'tcx, T: Encodable + Decodable> Lazy<T> {
-    crate fn decode<M: Metadata<'a, 'tcx>>(self, meta: M) -> T {
-        let mut dcx = meta.decoder(self.position.get());
+    crate fn decode<M: Metadata<'a, 'tcx>>(self, metadata: M) -> T {
+        let mut dcx = metadata.decoder(self.position.get());
         dcx.lazy_state = LazyState::NodeStart(self.position);
         T::decode(&mut dcx).unwrap()
     }
@@ -142,9 +142,9 @@ impl<'a, 'tcx, T: Encodable + Decodable> Lazy<T> {
 impl<'a: 'x, 'tcx: 'x, 'x, T: Encodable + Decodable> Lazy<[T]> {
     crate fn decode<M: Metadata<'a, 'tcx>>(
         self,
-        meta: M,
+        metadata: M,
     ) -> impl ExactSizeIterator<Item = T> + Captures<'a> + Captures<'tcx> + 'x {
-        let mut dcx = meta.decoder(self.position.get());
+        let mut dcx = metadata.decoder(self.position.get());
         dcx.lazy_state = LazyState::NodeStart(self.position);
         (0..self.meta).map(move |_| T::decode(&mut dcx).unwrap())
     }
@@ -481,7 +481,7 @@ impl<'a, 'tcx> CrateMetadata {
     }
 
     fn maybe_entry(&self, item_id: DefIndex) -> Option<Lazy<Entry<'tcx>>> {
-        self.root.per_def.entry.get(self.blob.raw_bytes(), item_id)
+        self.root.per_def.entry.get(self, item_id)
     }
 
     fn entry(&self, item_id: DefIndex) -> Entry<'tcx> {

src/librustc_metadata/table.rs

@@ -1,3 +1,4 @@
+use crate::decoder::Metadata;
 use crate::schema::*;
 
 use rustc::hir::def_id::{DefId, DefIndex};
@@ -158,10 +159,15 @@ impl<T> LazyMeta for Table<T> where Option<T>: FixedSizeEncoding {
 impl<T> Lazy<Table<T>> where Option<T>: FixedSizeEncoding {
     /// Given the metadata, extract out the value at a particular index (if any).
     #[inline(never)]
-    crate fn get(&self, bytes: &[u8], i: usize) -> Option<T> {
+    crate fn get<'a, 'tcx, M: Metadata<'a, 'tcx>>(
+        &self,
+        metadata: M,
+        i: usize,
+    ) -> Option<T> {
         debug!("Table::lookup: index={:?} len={:?}", i, self.meta);
 
-        <Option<T>>::read_from_bytes_at(&bytes[self.position.get()..][..self.meta], i)
+        let bytes = &metadata.raw_bytes()[self.position.get()..][..self.meta];
+        <Option<T>>::read_from_bytes_at(bytes, i)
     }
 }
 
@@ -201,7 +207,11 @@ impl<T> Lazy<PerDefTable<T>> where Option<T>: FixedSizeEncoding {
 
     /// Given the metadata, extract out the value at a particular DefIndex (if any).
     #[inline(never)]
-    crate fn get(&self, bytes: &[u8], def_index: DefIndex) -> Option<T> {
-        self.as_table().get(bytes, def_index.index())
+    crate fn get<'a, 'tcx, M: Metadata<'a, 'tcx>>(
+        &self,
+        metadata: M,
+        def_index: DefIndex,
+    ) -> Option<T> {
+        self.as_table().get(metadata, def_index.index())
     }
 }