Implement dual proc macro hashing

This changes the mechanism of `-Z dual-proc-macro` to record the host
proc macro hash in the transistive dependency information and use it
during dependency resolution instead of resolving only by name.

src/librustc/middle/cstore.rs

@@ -216,6 +216,7 @@ pub trait CrateStore {
     fn crate_is_private_dep_untracked(&self, cnum: CrateNum) -> bool;
     fn crate_disambiguator_untracked(&self, cnum: CrateNum) -> CrateDisambiguator;
     fn crate_hash_untracked(&self, cnum: CrateNum) -> Svh;
+    fn crate_host_hash_untracked(&self, cnum: CrateNum) -> Option<Svh>;
     fn item_generics_cloned_untracked(&self, def: DefId, sess: &Session) -> ty::Generics;
     fn postorder_cnums_untracked(&self) -> Vec<CrateNum>;
 

src/librustc/query/mod.rs

@@ -754,6 +754,10 @@ rustc_queries! {
             eval_always
             desc { "looking up the hash a crate" }
         }
+        query crate_host_hash(_: CrateNum) -> Option<Svh> {
+            eval_always
+            desc { "looking up the hash of a host version of a crate" }
+        }
         query original_crate_name(_: CrateNum) -> Symbol {
             eval_always
             desc { "looking up the original name a crate" }

src/librustc/ty/context.rs

@@ -3015,6 +3015,10 @@ pub fn provide(providers: &mut ty::query::Providers<'_>) {
         assert_eq!(cnum, LOCAL_CRATE);
         tcx.arena.alloc_slice(&tcx.cstore.crates_untracked())
     };
+    providers.crate_host_hash = |tcx, cnum| {
+        assert_ne!(cnum, LOCAL_CRATE);
+        tcx.cstore.crate_host_hash_untracked(cnum)
+    };
     providers.postorder_cnums = |tcx, cnum| {
         assert_eq!(cnum, LOCAL_CRATE);
         tcx.arena.alloc_slice(&tcx.cstore.postorder_cnums_untracked())

src/librustc_metadata/creader.rs

@@ -191,6 +191,7 @@ impl<'a> CrateLoader<'a> {
 
         let Library { source, metadata } = lib;
         let crate_root = metadata.get_root();
+        let host_hash = host_lib.as_ref().map(|lib| lib.metadata.get_root().hash);
         self.verify_no_symbol_conflicts(span, &crate_root);
 
         let private_dep = self.sess.opts.externs.get(&name.as_str())
@@ -245,6 +246,7 @@ impl<'a> CrateLoader<'a> {
             def_path_table,
             trait_impls,
             root: crate_root,
+            host_hash,
             blob: metadata,
             cnum_map,
             cnum,
@@ -283,9 +285,7 @@ impl<'a> CrateLoader<'a> {
                 LoadResult::Previous(cnum) => return Some((LoadResult::Previous(cnum), None)),
                 LoadResult::Loaded(library) => Some(LoadResult::Loaded(library))
             };
-            // Don't look for a matching hash when looking for the host crate.
-            // It won't be the same as the target crate hash
-            locate_ctxt.hash = None;
+            locate_ctxt.hash = locate_ctxt.host_hash;
             // Use the locate_ctxt when looking for the host proc macro crate, as that is required
             // so we want it to affect the error message
             (locate_ctxt, result)
@@ -334,10 +334,15 @@ impl<'a> CrateLoader<'a> {
         dep: Option<(&'b CratePaths, &'b CrateDep)>,
     ) -> Result<CrateNum, LoadError<'b>> {
         info!("resolving crate `{}`", name);
-        let (root, hash, extra_filename, path_kind) = match dep {
-            Some((root, dep)) =>
-                (Some(root), Some(&dep.hash), Some(&dep.extra_filename[..]), PathKind::Dependency),
-            None => (None, None, None, PathKind::Crate),
+        let (root, hash, host_hash, extra_filename, path_kind) = match dep {
+            Some((root, dep)) => (
+                Some(root),
+                Some(&dep.hash),
+                dep.host_hash.as_ref(),
+                Some(&dep.extra_filename[..]),
+                PathKind::Dependency
+            ),
+            None => (None, None, None, None, PathKind::Crate),
         };
         let result = if let Some(cnum) = self.existing_match(name, hash, path_kind) {
             (LoadResult::Previous(cnum), None)
@@ -348,6 +353,7 @@ impl<'a> CrateLoader<'a> {
                 span,
                 crate_name: name,
                 hash,
+                host_hash,
                 extra_filename,
                 filesearch: self.sess.target_filesearch(path_kind),
                 target: &self.sess.target.target,

src/librustc_metadata/cstore.rs

@@ -10,6 +10,7 @@ use rustc::mir::interpret::AllocDecodingState;
 use rustc_index::vec::IndexVec;
 use rustc::util::nodemap::FxHashMap;
 use rustc_data_structures::sync::{Lrc, Lock, MetadataRef, Once, AtomicCell};
+use rustc_data_structures::svh::Svh;
 use syntax::ast;
 use syntax::edition::Edition;
 use syntax_expand::base::SyntaxExtension;
@@ -87,6 +88,8 @@ crate struct CrateMetadata {
     /// Whether or not this crate should be consider a private dependency
     /// for purposes of the 'exported_private_dependencies' lint
     crate private_dep: bool,
+    /// The hash for the host proc macro. Used to support `-Z dual-proc-macro`.
+    crate host_hash: Option<Svh>,
 
     // --- Data used only for improving diagnostics ---
 

src/librustc_metadata/cstore_impl.rs

@@ -505,6 +505,10 @@ impl CrateStore for cstore::CStore {
         self.get_crate_data(cnum).root.hash
     }
 
+    fn crate_host_hash_untracked(&self, cnum: CrateNum) -> Option<Svh> {
+        self.get_crate_data(cnum).host_hash
+    }
+
     /// Returns the `DefKey` for a given `DefId`. This indicates the
     /// parent `DefId` as well as some idea of what kind of data the
     /// `DefId` refers to.

src/librustc_metadata/encoder.rs

@@ -1418,6 +1418,7 @@ impl EncodeContext<'tcx> {
                 let dep = CrateDep {
                     name: self.tcx.original_crate_name(cnum),
                     hash: self.tcx.crate_hash(cnum),
+                    host_hash: self.tcx.crate_host_hash(cnum),
                     kind: self.tcx.dep_kind(cnum),
                     extra_filename: self.tcx.extra_filename(cnum),
                 };

src/librustc_metadata/locator.rs

@@ -258,6 +258,7 @@ crate struct Context<'a> {
     pub span: Span,
     pub crate_name: Symbol,
     pub hash: Option<&'a Svh>,
+    pub host_hash: Option<&'a Svh>,
     pub extra_filename: Option<&'a str>,
     // points to either self.sess.target.target or self.sess.host, must match triple
     pub target: &'a Target,
@@ -929,6 +930,7 @@ pub fn find_plugin_registrar(
         span,
         crate_name: name,
         hash: None,
+        host_hash: None,
         extra_filename: None,
         filesearch: sess.host_filesearch(PathKind::Crate),
         target: &sess.host,

src/librustc_metadata/schema.rs

@@ -217,6 +217,7 @@ crate struct CrateRoot<'tcx> {
 crate struct CrateDep {
     pub name: ast::Name,
     pub hash: Svh,
+    pub host_hash: Option<Svh>,
     pub kind: DepKind,
     pub extra_filename: String,
 }