compiler/rustc_hir/src/tests.rs

   1 use crate::definitions::{DefKey, DefPathData, DisambiguatedDefPathData};
   2 use rustc_span::def_id::{DefPathHash, StableCrateId};
   3
   4 #[test]
   5 fn def_path_hash_depends_on_crate_id() {
   6     // This test makes sure that *both* halves of a DefPathHash depend on
   7     // the crate-id of the defining crate. This is a desirable property
   8     // because the crate-id can be more easily changed than the DefPath
   9     // of an item, so, in the case of a crate-local DefPathHash collision,
  10     // the user can simply "role the dice again" for all DefPathHashes in
  11     // the crate by changing the crate disambiguator (e.g. via bumping the
  12     // crate's version number).
  13
  14     let id0 = StableCrateId::new("foo", false, vec!["1".to_string()]);
  15     let id1 = StableCrateId::new("foo", false, vec!["2".to_string()]);
  16
  17     let h0 = mk_test_hash(id0);
  18     let h1 = mk_test_hash(id1);
  19
  20     assert_ne!(h0.stable_crate_id(), h1.stable_crate_id());
  21     assert_ne!(h0.local_hash(), h1.local_hash());
  22
  23     fn mk_test_hash(stable_crate_id: StableCrateId) -> DefPathHash {
  24         let parent_hash = DefPathHash::new(stable_crate_id, 0);
  25
  26         let key = DefKey {
  27             parent: None,
  28             disambiguated_data: DisambiguatedDefPathData {
  29                 data: DefPathData::CrateRoot,
  30                 disambiguator: 0,
  31             },
  32         };
  33
  34         key.compute_stable_hash(parent_hash)
  35     }
  36 }