1 //! Calculation and management of a Strict Version Hash for crates
3 //! The SVH is used for incremental compilation to track when HIR
4 //! nodes have changed between compilations, and also to detect
5 //! mismatches where we have two versions of the same crate that were
6 //! compiled from distinct sources.
8 use rustc_serialize::{Decodable, Decoder, Encodable, Encoder};
10 use std::hash::{Hash, Hasher};
12 use crate::stable_hasher;
14 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
20 /// Creates a new `Svh` given the hash. If you actually want to
21 /// compute the SVH from some HIR, you want the `calculate_svh`
22 /// function found in `rustc_incremental`.
23 pub fn new(hash: u64) -> Svh {
27 pub fn as_u64(&self) -> u64 {
31 pub fn to_string(&self) -> String {
32 format!("{:016x}", self.hash)
37 fn hash<H>(&self, state: &mut H)
41 self.hash.to_le().hash(state);
45 impl fmt::Display for Svh {
46 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
47 f.pad(&self.to_string())
51 impl<S: Encoder> Encodable<S> for Svh {
52 fn encode(&self, s: &mut S) -> Result<(), S::Error> {
53 s.emit_u64(self.as_u64().to_le())
57 impl<D: Decoder> Decodable<D> for Svh {
58 fn decode(d: &mut D) -> Svh {
59 Svh::new(u64::from_le(d.read_u64()))
63 impl<T> stable_hasher::HashStable<T> for Svh {
65 fn hash_stable(&self, ctx: &mut T, hasher: &mut stable_hasher::StableHasher) {
66 let Svh { hash } = *self;
67 hash.hash_stable(ctx, hasher);