bjoernager/rust
bjoernager/rust
1
Fork 0
Code Issues Pull requests Activity

Revert "Merge CrateDisambiguator into StableCrateId"

Browse source 
This reverts commit d0ec85d3fb.
This commit is contained in:
bjorn3 2021-06-01 16:32:13 +02:00
parent 6c5b6985fd
commit 8176ab8bc1
30 changed files with 207 additions and 127 deletions
Download patch file Download diff file Expand all files Collapse all files

40
compiler/rustc_span/src/def_id.rs
View file

@ -1,3 +1,4 @@
use crate::crate_disambiguator::CrateDisambiguator;
use crate::HashStableContext;
use rustc_data_structures::fingerprint::Fingerprint;
use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
@ -126,51 +127,26 @@ impl Borrow<Fingerprint> for DefPathHash {
}
}
/// A [StableCrateId] is a 64 bit hash of the crate name combined with all
/// `-Cmetadata` arguments. It is to [CrateNum] what [DefPathHash] is to
/// [DefId]. It is stable across compilation sessions.
/// A [StableCrateId] is a 64 bit hash of `(crate-name, crate-disambiguator)`. It
/// is to [CrateNum] what [DefPathHash] is to [DefId]. It is stable across
/// compilation sessions.
///
/// Since the ID is a hash value there is a (very small) chance that two crates
/// end up with the same [StableCrateId]. The compiler will check for such
/// collisions when loading crates and abort compilation in order to avoid
/// further trouble.
#[derive(Copy, Clone, Hash, PartialEq, Eq, PartialOrd, Ord, Debug)]
#[derive(HashStable_Generic, Encodable, Decodable)]
#[derive(Copy, Clone, Hash, PartialEq, Eq, PartialOrd, Ord, Debug, Encodable, Decodable)]
pub struct StableCrateId(u64);
impl StableCrateId {
pub fn to_u64(self) -> u64 {
self.0
}
/// Computes the stable ID for a crate with the given name and
/// `-Cmetadata` arguments.
pub fn new(crate_name: &str, is_exe: bool, mut metadata: Vec<String>) -> StableCrateId {
/// disambiguator.
pub fn new(crate_name: &str, crate_disambiguator: CrateDisambiguator) -> StableCrateId {
use std::hash::Hash;
use std::hash::Hasher;
let mut hasher = StableHasher::new();
crate_name.hash(&mut hasher);
// We don't want the stable crate id to dependent on the order
// -C metadata arguments, so sort them:
metadata.sort();
// Every distinct -C metadata value is only incorporated once:
metadata.dedup();
hasher.write(b"metadata");
for s in &metadata {
// Also incorporate the length of a metadata string, so that we generate
// different values for `-Cmetadata=ab -Cmetadata=c` and
// `-Cmetadata=a -Cmetadata=bc`
hasher.write_usize(s.len());
hasher.write(s.as_bytes());
}
// Also incorporate crate type, so that we don't get symbol conflicts when
// linking against a library of the same name, if this is an executable.
hasher.write(if is_exe { b"exe" } else { b"lib" });
crate_disambiguator.hash(&mut hasher);
StableCrateId(hasher.finish())
}
}