Auto merge of #46427 - michaelwoerister:transitive-svh, r=nikomatsakis

incr.comp.: Incorporate the stable commandline arg hash and SVHs of upstream crates into the SVH.

So far the SVH detected changes in the HIR, which is already very sensitive, but in order for `eval_always` queries to also be sensitive to changes in upstream crates, the SVH also needs to capture changes there.

This PR fixes [rust-icci/crossbeam](https://travis-ci.org/rust-icci/crossbeam/builds/308936448), but I have not yet been able to come up with a minimal regression test.

r? @nikomatsakis

src/librustc/hir/map/collector.rs

@@ -12,6 +12,7 @@
 
 use dep_graph::{DepGraph, DepKind, DepNodeIndex};
 use hir::intravisit::{Visitor, NestedVisitorMap};
+use middle::cstore::CrateStore;
 use session::CrateDisambiguator;
 use std::iter::repeat;
 use syntax::ast::{NodeId, CRATE_NODE_ID};
@@ -119,7 +120,9 @@ pub(super) fn root(krate: &'hir Crate,
     }
 
     pub(super) fn finalize_and_compute_crate_hash(self,
-                                                  crate_disambiguator: CrateDisambiguator)
+                                                  crate_disambiguator: CrateDisambiguator,
+                                                  cstore: &CrateStore,
+                                                  commandline_args_hash: u64)
                                                   -> Vec<MapEntry<'hir>> {
         let mut node_hashes: Vec<_> = self
             .hir_body_nodes
@@ -132,9 +135,23 @@ pub(super) fn finalize_and_compute_crate_hash(self,
 
         node_hashes.sort_unstable_by(|&(ref d1, _), &(ref d2, _)| d1.cmp(d2));
 
+        let mut upstream_crates: Vec<_> = cstore.crates_untracked().iter().map(|&cnum| {
+            let name = cstore.crate_name_untracked(cnum).as_str();
+            let disambiguator = cstore.crate_disambiguator_untracked(cnum)
+                                      .to_fingerprint();
+            let hash = cstore.crate_hash_untracked(cnum);
+            (name, disambiguator, hash)
+        }).collect();
+
+        upstream_crates.sort_unstable_by(|&(name1, dis1, _), &(name2, dis2, _)| {
+            (name1, dis1).cmp(&(name2, dis2))
+        });
+
         self.dep_graph.with_task(DepNode::new_no_params(DepKind::Krate),
                                  &self.hcx,
-                                 (node_hashes, crate_disambiguator.to_fingerprint()),
+                                 ((node_hashes, upstream_crates),
+                                  (commandline_args_hash,
+                                   crate_disambiguator.to_fingerprint())),
                                  identity_fn);
         self.map
     }

src/librustc/hir/map/mod.rs

@@ -1059,7 +1059,10 @@ pub fn map_crate<'hir>(sess: &::session::Session,
         intravisit::walk_crate(&mut collector, &forest.krate);
 
         let crate_disambiguator = sess.local_crate_disambiguator();
-        collector.finalize_and_compute_crate_hash(crate_disambiguator)
+        let cmdline_args = sess.opts.dep_tracking_hash();
+        collector.finalize_and_compute_crate_hash(crate_disambiguator,
+                                                  cstore,
+                                                  cmdline_args)
     };
 
     if log_enabled!(::log::LogLevel::Debug) {