Handle path prefix mapping in a more stable way when computing the crate hash

src/librustc/hir/map/collector.rs

@@ -9,14 +9,15 @@
 // except according to those terms.
 
 use super::*;
-
 use dep_graph::{DepGraph, DepKind, DepNodeIndex};
+use hir::def_id::{LOCAL_CRATE, CrateNum};
 use hir::intravisit::{Visitor, NestedVisitorMap};
 use hir::svh::Svh;
 use middle::cstore::CrateStore;
 use session::CrateDisambiguator;
 use std::iter::repeat;
 use syntax::ast::{NodeId, CRATE_NODE_ID};
+use syntax::codemap::CodeMap;
 use syntax_pos::Span;
 
 use ich::StableHashingContext;
@@ -123,6 +124,7 @@ impl<'a, 'hir> NodeCollector<'a, 'hir> {
  pub(super) fn finalize_and_compute_crate_hash(self,
  crate_disambiguator: CrateDisambiguator,
  cstore: &CrateStore,
+ codemap: &CodeMap,
  commandline_args_hash: u64)
  -> (Vec<MapEntry<'hir>>, Svh) {
  let mut node_hashes: Vec<_> = self
@@ -147,11 +149,25 @@ impl<'a, 'hir> NodeCollector<'a, 'hir> {
  (name1, dis1).cmp(&(name2, dis2))
  });
 
+ // We hash the final, remapped names of all local source files so we
+ // don't have to include the path prefix remapping commandline args.
+ // If we included the full mapping in the SVH, we could only have
+ // reproducible builds by compiling from the same directory. So we just
+ // hash the result of the mapping instead of the mapping itself.
+ let mut source_file_names: Vec<_> = codemap
+ .files()
+ .iter()
+ .filter(|filemap| CrateNum::from_u32(filemap.crate_of_origin) == LOCAL_CRATE)
+ .map(|filemap| filemap.name_hash)
+ .collect();
+
+ source_file_names.sort_unstable();
+
  let (_, crate_dep_node_index) = self
  .dep_graph
  .with_task(DepNode::new_no_params(DepKind::Krate),
  &self.hcx,
- ((node_hashes, upstream_crates),
+ (((node_hashes, upstream_crates), source_file_names),
  (commandline_args_hash,
  crate_disambiguator.to_fingerprint())),
  identity_fn);

src/librustc/hir/map/mod.rs

@@ -1065,6 +1065,7 @@ pub fn map_crate<'hir>(sess: &::session::Session,
  let cmdline_args = sess.opts.dep_tracking_hash();
  collector.finalize_and_compute_crate_hash(crate_disambiguator,
  cstore,
+ sess.codemap(),
  cmdline_args)
  };
 

src/librustc/session/config.rs

@@ -1269,9 +1269,9 @@ options! {DebuggingOptions, DebuggingSetter, basic_debugging_options,
  "set the optimization fuel quota for a crate"),
  print_fuel: Option<String> = (None, parse_opt_string, [TRACKED],
  "make Rustc print the total optimization fuel used by a crate"),
- remap_path_prefix_from: Vec<PathBuf> = (vec![], parse_pathbuf_push, [TRACKED],
+ remap_path_prefix_from: Vec<PathBuf> = (vec![], parse_pathbuf_push, [UNTRACKED],
  "add a source pattern to the file path remapping config"),
- remap_path_prefix_to: Vec<PathBuf> = (vec![], parse_pathbuf_push, [TRACKED],
+ remap_path_prefix_to: Vec<PathBuf> = (vec![], parse_pathbuf_push, [UNTRACKED],
  "add a mapping target to the file path remapping config"),
  force_unstable_if_unmarked: bool = (false, parse_bool, [TRACKED],
  "force all crates to be `rustc_private` unstable"),
@@ -1717,7 +1717,7 @@ pub fn build_session_options_and_crate_config(matches: &getopts::Matches)
  }
 
  let remap_path_prefix_sources = debugging_opts.remap_path_prefix_from.len();
- let remap_path_prefix_targets = debugging_opts.remap_path_prefix_from.len();
+ let remap_path_prefix_targets = debugging_opts.remap_path_prefix_to.len();
 
  if remap_path_prefix_targets < remap_path_prefix_sources {
  for source in &debugging_opts.remap_path_prefix_from[remap_path_prefix_targets..] {