rustc_metadata: parametrize schema::CrateRoot by 'tcx.

Author: eddyb

Diff for: src/librustc_metadata/creader.rs

@@ -162,7 +162,7 @@ impl<'a> CrateLoader<'a> {
 
     fn verify_no_symbol_conflicts(&self,
                                   span: Span,
-                                  root: &CrateRoot) {
+                                  root: &CrateRoot<'_>) {
         // Check for (potential) conflicts with the local crate
         if self.local_crate_name == root.name &&
            self.sess.local_crate_disambiguator() == root.disambiguator {
@@ -476,7 +476,7 @@ impl<'a> CrateLoader<'a> {
     // Go through the crate metadata and load any crates that it references
     fn resolve_crate_deps(&mut self,
                           root: &Option<CratePaths>,
-                          crate_root: &CrateRoot,
+                          crate_root: &CrateRoot<'_>,
                           metadata: &MetadataBlob,
                           krate: CrateNum,
                           span: Span,
@@ -582,7 +582,7 @@ impl<'a> CrateLoader<'a> {
     /// implemented as dynamic libraries, but we have a possible future where
     /// custom derive (and other macro-1.1 style features) are implemented via
     /// executables and custom IPC.
-    fn load_derive_macros(&mut self, root: &CrateRoot, dylib: Option<PathBuf>, span: Span)
+    fn load_derive_macros(&mut self, root: &CrateRoot<'_>, dylib: Option<PathBuf>, span: Span)
                           -> Vec<(ast::Name, Lrc<SyntaxExtension>)> {
         use std::{env, mem};
         use crate::dynamic_lib::DynamicLibrary;

Diff for: src/librustc_metadata/cstore.rs

@@ -64,7 +64,11 @@ pub struct CrateMetadata {
     /// Used for decoding interpret::AllocIds in a cached & thread-safe manner.
     pub alloc_decoding_state: AllocDecodingState,
 
-    pub root: schema::CrateRoot,
+    // NOTE(eddyb) we pass `'static` to a `'tcx` parameter because this
+    // lifetime is only used behind `Lazy` / `LazySeq`, and therefore
+    // acts like an universal (`for<'tcx>`), that is paired up with
+    // whichever `TyCtxt` is being used to decode those values.
+    pub root: schema::CrateRoot<'static>,
 
     /// For each public item in this crate, we encode a key. When the
     /// crate is loaded, we read all the keys and put them in this

Diff for: src/librustc_metadata/cstore_impl.rs

@@ -246,12 +246,7 @@ provide! { <'tcx> tcx, def_id, other, cdata,
 
     used_crate_source => { Lrc::new(cdata.source.clone()) }
 
-    exported_symbols => {
-        let cnum = cdata.cnum;
-        assert!(cnum != LOCAL_CRATE);
-
-        Arc::new(cdata.exported_symbols(tcx))
-    }
+    exported_symbols => { Arc::new(cdata.exported_symbols(tcx)) }
 }
 
 pub fn provide<'tcx>(providers: &mut Providers<'tcx>) {

Diff for: src/librustc_metadata/decoder.rs

@@ -365,7 +365,7 @@ for DecodeContext<'a, 'tcx> {
 
 implement_ty_decoder!( DecodeContext<'a, 'tcx> );
 
-impl<'a, 'tcx> MetadataBlob {
+impl<'tcx> MetadataBlob {
     pub fn is_compatible(&self) -> bool {
         self.raw_bytes().starts_with(METADATA_HEADER)
     }
@@ -374,7 +374,7 @@ impl<'a, 'tcx> MetadataBlob {
         Lazy::with_position(METADATA_HEADER.len() + 4).decode(self)
     }
 
-    pub fn get_root(&self) -> CrateRoot {
+    pub fn get_root(&self) -> CrateRoot<'tcx> {
         let slice = self.raw_bytes();
         let offset = METADATA_HEADER.len();
         let pos = (((slice[offset + 0] as u32) << 24) | ((slice[offset + 1] as u32) << 16) |
@@ -444,7 +444,7 @@ impl<'tcx> EntryKind<'tcx> {
 ///  |- proc macro #0 (DefIndex 1:N)
 ///  |- proc macro #1 (DefIndex 1:N+1)
 ///  \- ...
-crate fn proc_macro_def_path_table(crate_root: &CrateRoot,
+crate fn proc_macro_def_path_table(crate_root: &CrateRoot<'_>,
                                    proc_macros: &[(ast::Name, Lrc<SyntaxExtension>)])
                                    -> DefPathTable
 {
@@ -1126,10 +1126,7 @@ impl<'a, 'tcx> CrateMetadata {
             // link those in so we skip those crates.
             vec![]
         } else {
-            let lazy_seq: LazySeq<(ExportedSymbol<'tcx>, SymbolExportLevel)> =
-                LazySeq::with_position_and_length(self.root.exported_symbols.position,
-                                                  self.root.exported_symbols.len);
-            lazy_seq.decode((self, tcx)).collect()
+            self.root.exported_symbols.decode((self, tcx)).collect()
         }
     }
 

Diff for: src/librustc_metadata/encoder.rs

@@ -309,7 +309,7 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
         op(&mut IsolatedEncoder::new(self), data)
     }
 
-    fn encode_info_for_items(&mut self) -> Index {
+    fn encode_info_for_items(&mut self) -> Index<'tcx> {
         let krate = self.tcx.hir().krate();
         let mut index = IndexBuilder::new(self);
         let vis = Spanned { span: syntax_pos::DUMMY_SP, node: hir::VisibilityKind::Public };
@@ -371,7 +371,7 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
         self.lazy_seq_ref(adapted.iter().map(|rc| &**rc))
     }
 
-    fn encode_crate_root(&mut self) -> Lazy<CrateRoot> {
+    fn encode_crate_root(&mut self) -> Lazy<CrateRoot<'tcx>> {
         let mut i = self.position();
 
         let crate_deps = self.tracked(IsolatedEncoder::encode_crate_deps, ());
@@ -1595,13 +1595,13 @@ impl<'a, 'b: 'a, 'tcx: 'b> IsolatedEncoder<'a, 'b, 'tcx> {
     // symbol associated with them (they weren't translated) or if they're an FFI
     // definition (as that's not defined in this crate).
     fn encode_exported_symbols(&mut self,
-                               exported_symbols: &[(ExportedSymbol<'_>, SymbolExportLevel)])
-                               -> EncodedExportedSymbols {
+                               exported_symbols: &[(ExportedSymbol<'tcx>, SymbolExportLevel)])
+                               -> LazySeq<(ExportedSymbol<'tcx>, SymbolExportLevel)> {
         // The metadata symbol name is special. It should not show up in
         // downstream crates.
         let metadata_symbol_name = SymbolName::new(&metadata_symbol_name(self.tcx));
 
-        let lazy_seq = self.lazy_seq(exported_symbols
+        self.lazy_seq(exported_symbols
             .iter()
             .filter(|&&(ref exported_symbol, _)| {
                 match *exported_symbol {
@@ -1611,12 +1611,7 @@ impl<'a, 'b: 'a, 'tcx: 'b> IsolatedEncoder<'a, 'b, 'tcx> {
                     _ => true,
                 }
             })
-            .cloned());
-
-        EncodedExportedSymbols {
-            len: lazy_seq.len,
-            position: lazy_seq.position,
-        }
+            .cloned())
     }
 
     fn encode_dylib_dependency_formats(&mut self, _: ()) -> LazySeq<Option<LinkagePreference>> {

Diff for: src/librustc_metadata/index.rs

@@ -2,6 +2,7 @@ use crate::schema::*;
 
 use rustc::hir::def_id::{DefId, DefIndex};
 use rustc_serialize::opaque::Encoder;
+use std::marker::PhantomData;
 use std::u32;
 use log::debug;
 
@@ -74,23 +75,25 @@ impl FixedSizeEncoding for u32 {
 /// `u32::MAX`. Whenever an index is visited, we fill in the
 /// appropriate spot by calling `record_position`. We should never
 /// visit the same index twice.
-pub struct Index {
+pub struct Index<'tcx> {
     positions: Vec<u8>,
+    _marker: PhantomData<&'tcx ()>,
 }
 
-impl Index {
-    pub fn new(max_index: usize) -> Index {
+impl Index<'tcx> {
+    pub fn new(max_index: usize) -> Self {
         Index {
             positions: vec![0xff; max_index * 4],
+            _marker: PhantomData,
         }
     }
 
-    pub fn record(&mut self, def_id: DefId, entry: Lazy<Entry<'_>>) {
+    pub fn record(&mut self, def_id: DefId, entry: Lazy<Entry<'tcx>>) {
         assert!(def_id.is_local());
         self.record_index(def_id.index, entry);
     }
 
-    pub fn record_index(&mut self, item: DefIndex, entry: Lazy<Entry<'_>>) {
+    pub fn record_index(&mut self, item: DefIndex, entry: Lazy<Entry<'tcx>>) {
         assert!(entry.position < (u32::MAX as usize));
         let position = entry.position as u32;
         let array_index = item.index();
@@ -105,7 +108,7 @@ impl Index {
         position.write_to_bytes_at(positions, array_index)
     }
 
-    pub fn write_index(&self, buf: &mut Encoder) -> LazySeq<Index> {
+    pub fn write_index(&self, buf: &mut Encoder) -> LazySeq<Self> {
         let pos = buf.position();
 
         // First we write the length of the lower range ...
@@ -116,7 +119,7 @@ impl Index {
     }
 }
 
-impl<'tcx> LazySeq<Index> {
+impl LazySeq<Index<'tcx>> {
     /// Given the metadata, extract out the offset of a particular
     /// DefIndex (if any).
     #[inline(never)]

Diff for: src/librustc_metadata/index_builder.rs

@@ -60,7 +60,7 @@ use std::ops::{Deref, DerefMut};
 /// Builder that can encode new items, adding them into the index.
 /// Item encoding cannot be nested.
 pub struct IndexBuilder<'a, 'b: 'a, 'tcx: 'b> {
-    items: Index,
+    items: Index<'tcx>,
     pub ecx: &'a mut EncodeContext<'b, 'tcx>,
 }
 
@@ -123,7 +123,7 @@ impl<'a, 'b, 'tcx> IndexBuilder<'a, 'b, 'tcx> {
         })
     }
 
-    pub fn into_items(self) -> Index {
+    pub fn into_items(self) -> Index<'tcx> {
         self.items
     }
 }

Diff for: src/librustc_metadata/lib.rs

@@ -2,6 +2,7 @@
 
 #![feature(box_patterns)]
 #![feature(drain_filter)]
+#![feature(in_band_lifetimes)]
 #![feature(libc)]
 #![feature(nll)]
 #![feature(proc_macro_internals)]

Diff for: src/librustc_metadata/schema.rs

@@ -4,6 +4,7 @@ use rustc::hir;
 use rustc::hir::def::{self, CtorKind};
 use rustc::hir::def_id::{DefIndex, DefId, CrateNum};
 use rustc::ich::StableHashingContext;
+use rustc::middle::exported_symbols::{ExportedSymbol, SymbolExportLevel};
 use rustc::middle::cstore::{DepKind, LinkagePreference, NativeLibrary, ForeignModule};
 use rustc::middle::lang_items;
 use rustc::mir;
@@ -174,7 +175,7 @@ pub enum LazyState {
 }
 
 #[derive(RustcEncodable, RustcDecodable)]
-pub struct CrateRoot {
+pub struct CrateRoot<'tcx> {
     pub name: Symbol,
     pub triple: TargetTriple,
     pub extra_filename: String,
@@ -199,10 +200,10 @@ pub struct CrateRoot {
     pub source_map: LazySeq<syntax_pos::SourceFile>,
     pub def_path_table: Lazy<hir::map::definitions::DefPathTable>,
     pub impls: LazySeq<TraitImpls>,
-    pub exported_symbols: EncodedExportedSymbols,
+    pub exported_symbols: LazySeq<(ExportedSymbol<'tcx>, SymbolExportLevel)>,
     pub interpret_alloc_index: LazySeq<u32>,
 
-    pub index: LazySeq<index::Index>,
+    pub index: LazySeq<index::Index<'tcx>>,
 
     pub compiler_builtins: bool,
     pub needs_allocator: bool,
@@ -577,9 +578,3 @@ impl_stable_hash_for!(struct GeneratorData<'tcx> { layout });
 // Tags used for encoding Spans:
 pub const TAG_VALID_SPAN: u8 = 0;
 pub const TAG_INVALID_SPAN: u8 = 1;
-
-#[derive(RustcEncodable, RustcDecodable)]
-pub struct EncodedExportedSymbols {
-    pub position: usize,
-    pub len: usize,
-}