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Auto merge of #89836 - pierwill:fix-85142-crate-hash, r=wesleywiser

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Include rustc version in `rustc_span::StableCrateId`

`rustc_span::def_id::StableCrateId` is a hash of various data about a crate during compilation. This PR includes the version of `rustc` in the input when computing this hash. From a cursory reading of [RFC 2603](https://rust-lang.github.io/rfcs/2603-rust-symbol-name-mangling-v0.html), this appears to be acceptable within that design.

In order to pass the `mir-opt` and `ui` test suites, this adds new [normalization for hashes and symbol names in `compiletest`](https://github.com/rust-lang/rust/pull/89836/files#diff-03a0567fa80ca04ed5a55f9ac5c711b4f84659be2d0ac4a984196d581c04f76b). These are enabled by default, but we might prefer it to be configurable.

In the UI tests, I had to truncate a significant amount of error annotations in v0 symbols (and maybe some legacy) in order to get the normalization to work correctly. (See https://github.com/rust-lang/rust/issues/90116.)

Closes #85142.
This commit is contained in:
bors 2021-12-16 02:21:30 +00:00
commit 9e1aff82e6
53 changed files with 333 additions and 205 deletions
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27
compiler/rustc_span/src/def_id.rs
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@ -127,14 +127,17 @@ 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 a crate name, together with all
/// `-Cmetadata` arguments, and some other data. 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
/// Since the ID is a hash value, there is a 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.
///
/// See the discussion in [`DefId`] for more information
/// on the possibility of hash collisions in rustc,
#[derive(Copy, Clone, Hash, PartialEq, Eq, PartialOrd, Ord, Debug)]
#[derive(HashStable_Generic, Encodable, Decodable)]
pub struct StableCrateId(pub(crate) u64);
@ -150,7 +153,7 @@ impl StableCrateId {
let mut hasher = StableHasher::new();
crate_name.hash(&mut hasher);
// We don't want the stable crate id to dependent on the order
// We don't want the stable crate ID to depend on the order of
// -C metadata arguments, so sort them:
metadata.sort();
// Every distinct -C metadata value is only incorporated once:
@ -169,6 +172,18 @@ impl StableCrateId {
// linking against a library of the same name, if this is an executable.
hasher.write(if is_exe { b"exe" } else { b"lib" });
// Also incorporate the rustc version. Otherwise, with -Zsymbol-mangling-version=v0
// and no -Cmetadata, symbols from the same crate compiled with different versions of
// rustc are named the same.
//
// RUSTC_FORCE_INCR_COMP_ARTIFACT_HEADER is used to inject rustc version information
// during testing.
if let Some(val) = std::env::var_os("RUSTC_FORCE_INCR_COMP_ARTIFACT_HEADER") {
hasher.write(val.to_string_lossy().into_owned().as_bytes())
} else {
hasher.write(option_env!("CFG_VERSION").unwrap_or("unknown version").as_bytes());
}
StableCrateId(hasher.finish())
}
}