Auto merge of rust-lang#85891 - bjorn3:revert_merge_crate_disambiguator, r=Mark-Simulacrum

Revert "Merge CrateDisambiguator into StableCrateId"

This reverts rust-lang#85804

Author: bors

compiler/rustc_hir/src/definitions.rs

@@ -14,6 +14,7 @@ use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::stable_hasher::StableHasher;
 use rustc_data_structures::unhash::UnhashMap;
 use rustc_index::vec::IndexVec;
+use rustc_span::crate_disambiguator::CrateDisambiguator;
 use rustc_span::hygiene::ExpnId;
 use rustc_span::symbol::{kw, sym, Symbol};
 
@@ -338,7 +339,7 @@ impl Definitions {
     }
 
     /// Adds a root definition (no parent) and a few other reserved definitions.
-    pub fn new(stable_crate_id: StableCrateId) -> Definitions {
+    pub fn new(crate_name: &str, crate_disambiguator: CrateDisambiguator) -> Definitions {
         let key = DefKey {
             parent: None,
             disambiguated_data: DisambiguatedDefPathData {
@@ -347,6 +348,7 @@ impl Definitions {
             },
         };
 
+        let stable_crate_id = StableCrateId::new(crate_name, crate_disambiguator);
         let parent_hash = DefPathHash::new(stable_crate_id, 0);
         let def_path_hash = key.compute_stable_hash(parent_hash);
 

compiler/rustc_hir/src/tests.rs

@@ -1,4 +1,6 @@
 use crate::definitions::{DefKey, DefPathData, DisambiguatedDefPathData};
+use rustc_data_structures::fingerprint::Fingerprint;
+use rustc_span::crate_disambiguator::CrateDisambiguator;
 use rustc_span::def_id::{DefPathHash, StableCrateId};
 
 #[test]
@@ -11,16 +13,17 @@ fn def_path_hash_depends_on_crate_id() {
     // the crate by changing the crate disambiguator (e.g. via bumping the
     // crate's version number).
 
-    let id0 = StableCrateId::new("foo", false, vec!["1".to_string()]);
-    let id1 = StableCrateId::new("foo", false, vec!["2".to_string()]);
+    let d0 = CrateDisambiguator::from(Fingerprint::new(12, 34));
+    let d1 = CrateDisambiguator::from(Fingerprint::new(56, 78));
 
-    let h0 = mk_test_hash(id0);
-    let h1 = mk_test_hash(id1);
+    let h0 = mk_test_hash("foo", d0);
+    let h1 = mk_test_hash("foo", d1);
 
     assert_ne!(h0.stable_crate_id(), h1.stable_crate_id());
     assert_ne!(h0.local_hash(), h1.local_hash());
 
-    fn mk_test_hash(stable_crate_id: StableCrateId) -> DefPathHash {
+    fn mk_test_hash(crate_name: &str, crate_disambiguator: CrateDisambiguator) -> DefPathHash {
+        let stable_crate_id = StableCrateId::new(crate_name, crate_disambiguator);
         let parent_hash = DefPathHash::new(stable_crate_id, 0);
 
         let key = DefKey {

compiler/rustc_incremental/src/persist/fs.rs

@@ -108,7 +108,7 @@ use rustc_data_structures::svh::Svh;
 use rustc_data_structures::{base_n, flock};
 use rustc_errors::ErrorReported;
 use rustc_fs_util::{link_or_copy, LinkOrCopy};
-use rustc_session::{Session, StableCrateId};
+use rustc_session::{CrateDisambiguator, Session};
 
 use std::fs as std_fs;
 use std::io;
@@ -189,7 +189,7 @@ pub fn in_incr_comp_dir(incr_comp_session_dir: &Path, file_name: &str) -> PathBu
 pub fn prepare_session_directory(
     sess: &Session,
     crate_name: &str,
-    stable_crate_id: StableCrateId,
+    crate_disambiguator: CrateDisambiguator,
 ) -> Result<(), ErrorReported> {
     if sess.opts.incremental.is_none() {
         return Ok(());
@@ -200,7 +200,7 @@ pub fn prepare_session_directory(
     debug!("prepare_session_directory");
 
     // {incr-comp-dir}/{crate-name-and-disambiguator}
-    let crate_dir = crate_path(sess, crate_name, stable_crate_id);
+    let crate_dir = crate_path(sess, crate_name, crate_disambiguator);
     debug!("crate-dir: {}", crate_dir.display());
     create_dir(sess, &crate_dir, "crate")?;
 
@@ -648,12 +648,19 @@ fn string_to_timestamp(s: &str) -> Result<SystemTime, ()> {
     Ok(UNIX_EPOCH + duration)
 }
 
-fn crate_path(sess: &Session, crate_name: &str, stable_crate_id: StableCrateId) -> PathBuf {
+fn crate_path(
+    sess: &Session,
+    crate_name: &str,
+    crate_disambiguator: CrateDisambiguator,
+) -> PathBuf {
     let incr_dir = sess.opts.incremental.as_ref().unwrap().clone();
 
-    let stable_crate_id = base_n::encode(stable_crate_id.to_u64() as u128, INT_ENCODE_BASE);
+    // The full crate disambiguator is really long. 64 bits of it should be
+    // sufficient.
+    let crate_disambiguator = crate_disambiguator.to_fingerprint().to_smaller_hash();
+    let crate_disambiguator = base_n::encode(crate_disambiguator as u128, INT_ENCODE_BASE);
 
-    let crate_name = format!("{}-{}", crate_name, stable_crate_id);
+    let crate_name = format!("{}-{}", crate_name, crate_disambiguator);
     incr_dir.join(crate_name)
 }
 

compiler/rustc_interface/src/passes.rs

@@ -12,7 +12,7 @@ use rustc_data_structures::temp_dir::MaybeTempDir;
 use rustc_data_structures::{box_region_allow_access, declare_box_region_type, parallel};
 use rustc_errors::{ErrorReported, PResult};
 use rustc_expand::base::ExtCtxt;
-use rustc_hir::def_id::{StableCrateId, LOCAL_CRATE};
+use rustc_hir::def_id::LOCAL_CRATE;
 use rustc_hir::Crate;
 use rustc_lint::LintStore;
 use rustc_metadata::creader::CStore;
@@ -170,13 +170,9 @@ pub fn register_plugins<'a>(
     let crate_types = util::collect_crate_types(sess, &krate.attrs);
     sess.init_crate_types(crate_types);
 
-    let stable_crate_id = StableCrateId::new(
-        crate_name,
-        sess.crate_types().contains(&CrateType::Executable),
-        sess.opts.cg.metadata.clone(),
-    );
-    sess.stable_crate_id.set(stable_crate_id).expect("not yet initialized");
-    rustc_incremental::prepare_session_directory(sess, &crate_name, stable_crate_id)?;
+    let disambiguator = util::compute_crate_disambiguator(sess);
+    sess.crate_disambiguator.set(disambiguator).expect("not yet initialized");
+    rustc_incremental::prepare_session_directory(sess, &crate_name, disambiguator)?;
 
     if sess.opts.incremental.is_some() {
         sess.time("incr_comp_garbage_collect_session_directories", || {

compiler/rustc_interface/src/util.rs

@@ -2,9 +2,11 @@ use rustc_ast::mut_visit::{visit_clobber, MutVisitor, *};
 use rustc_ast::ptr::P;
 use rustc_ast::{self as ast, AttrVec, BlockCheckMode};
 use rustc_codegen_ssa::traits::CodegenBackend;
+use rustc_data_structures::fingerprint::Fingerprint;
 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 #[cfg(parallel_compiler)]
 use rustc_data_structures::jobserver;
+use rustc_data_structures::stable_hasher::StableHasher;
 use rustc_data_structures::sync::Lrc;
 use rustc_errors::registry::Registry;
 use rustc_metadata::dynamic_lib::DynamicLibrary;
@@ -16,6 +18,7 @@ use rustc_session::config::{self, CrateType};
 use rustc_session::config::{ErrorOutputType, Input, OutputFilenames};
 use rustc_session::lint::{self, BuiltinLintDiagnostics, LintBuffer};
 use rustc_session::parse::CrateConfig;
+use rustc_session::CrateDisambiguator;
 use rustc_session::{early_error, filesearch, output, DiagnosticOutput, Session};
 use rustc_span::edition::Edition;
 use rustc_span::lev_distance::find_best_match_for_name;
@@ -484,6 +487,39 @@ pub fn get_codegen_sysroot(
     }
 }
 
+pub(crate) fn compute_crate_disambiguator(session: &Session) -> CrateDisambiguator {
+    use std::hash::Hasher;
+
+    // The crate_disambiguator is a 128 bit hash. The disambiguator is fed
+    // into various other hashes quite a bit (symbol hashes, incr. comp. hashes,
+    // debuginfo type IDs, etc), so we don't want it to be too wide. 128 bits
+    // should still be safe enough to avoid collisions in practice.
+    let mut hasher = StableHasher::new();
+
+    let mut metadata = session.opts.cg.metadata.clone();
+    // We don't want the crate_disambiguator 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.
+    let is_exe = session.crate_types().contains(&CrateType::Executable);
+    hasher.write(if is_exe { b"exe" } else { b"lib" });
+
+    CrateDisambiguator::from(hasher.finish::<Fingerprint>())
+}
+
 pub(crate) fn check_attr_crate_type(
     sess: &Session,
     attrs: &[ast::Attribute],

compiler/rustc_metadata/src/creader.rs

@@ -21,7 +21,7 @@ use rustc_session::config::{self, CrateType, ExternLocation};
 use rustc_session::lint::{self, BuiltinLintDiagnostics, ExternDepSpec};
 use rustc_session::output::validate_crate_name;
 use rustc_session::search_paths::PathKind;
-use rustc_session::Session;
+use rustc_session::{CrateDisambiguator, Session};
 use rustc_span::edition::Edition;
 use rustc_span::symbol::{sym, Symbol};
 use rustc_span::{Span, DUMMY_SP};
@@ -222,8 +222,10 @@ impl<'a> CrateLoader<'a> {
         metadata_loader: &'a MetadataLoaderDyn,
         local_crate_name: &str,
     ) -> Self {
+        let local_crate_stable_id =
+            StableCrateId::new(local_crate_name, sess.local_crate_disambiguator());
         let mut stable_crate_ids = FxHashMap::default();
-        stable_crate_ids.insert(sess.local_stable_crate_id(), LOCAL_CRATE);
+        stable_crate_ids.insert(local_crate_stable_id, LOCAL_CRATE);
 
         CrateLoader {
             sess,
@@ -325,14 +327,17 @@ impl<'a> CrateLoader<'a> {
 
     fn verify_no_symbol_conflicts(&self, root: &CrateRoot<'_>) -> Result<(), CrateError> {
         // Check for (potential) conflicts with the local crate
-        if self.sess.local_stable_crate_id() == root.stable_crate_id() {
+        if self.local_crate_name == root.name()
+            && self.sess.local_crate_disambiguator() == root.disambiguator()
+        {
             return Err(CrateError::SymbolConflictsCurrent(root.name()));
         }
 
         // Check for conflicts with any crate loaded so far
         let mut res = Ok(());
         self.cstore.iter_crate_data(|_, other| {
-            if other.stable_crate_id() == root.stable_crate_id() && // same stable crate id
+            if other.name() == root.name() && // same crate-name
+               other.disambiguator() == root.disambiguator() && // same crate-disambiguator
                other.hash() != root.hash()
             {
                 // but different SVH
@@ -406,7 +411,7 @@ impl<'a> CrateLoader<'a> {
                 None => (&source, &crate_root),
             };
             let dlsym_dylib = dlsym_source.dylib.as_ref().expect("no dylib for a proc-macro crate");
-            Some(self.dlsym_proc_macros(&dlsym_dylib.0, dlsym_root.stable_crate_id())?)
+            Some(self.dlsym_proc_macros(&dlsym_dylib.0, dlsym_root.disambiguator())?)
         } else {
             None
         };
@@ -659,7 +664,7 @@ impl<'a> CrateLoader<'a> {
     fn dlsym_proc_macros(
         &self,
         path: &Path,
-        stable_crate_id: StableCrateId,
+        disambiguator: CrateDisambiguator,
     ) -> Result<&'static [ProcMacro], CrateError> {
         // Make sure the path contains a / or the linker will search for it.
         let path = env::current_dir().unwrap().join(path);
@@ -668,7 +673,7 @@ impl<'a> CrateLoader<'a> {
             Err(s) => return Err(CrateError::DlOpen(s)),
         };
 
-        let sym = self.sess.generate_proc_macro_decls_symbol(stable_crate_id);
+        let sym = self.sess.generate_proc_macro_decls_symbol(disambiguator);
         let decls = unsafe {
             let sym = match lib.symbol(&sym) {
                 Ok(f) => f,

compiler/rustc_metadata/src/locator.rs

@@ -226,7 +226,7 @@ use rustc_session::config::{self, CrateType};
 use rustc_session::filesearch::{FileDoesntMatch, FileMatches, FileSearch};
 use rustc_session::search_paths::PathKind;
 use rustc_session::utils::CanonicalizedPath;
-use rustc_session::{Session, StableCrateId};
+use rustc_session::{CrateDisambiguator, Session};
 use rustc_span::symbol::{sym, Symbol};
 use rustc_span::Span;
 use rustc_target::spec::{Target, TargetTriple};
@@ -787,7 +787,7 @@ pub fn find_plugin_registrar(
     metadata_loader: &dyn MetadataLoader,
     span: Span,
     name: Symbol,
-) -> (PathBuf, StableCrateId) {
+) -> (PathBuf, CrateDisambiguator) {
     match find_plugin_registrar_impl(sess, metadata_loader, name) {
         Ok(res) => res,
         // `core` is always available if we got as far as loading plugins.
@@ -799,7 +799,7 @@ fn find_plugin_registrar_impl<'a>(
     sess: &'a Session,
     metadata_loader: &dyn MetadataLoader,
     name: Symbol,
-) -> Result<(PathBuf, StableCrateId), CrateError> {
+) -> Result<(PathBuf, CrateDisambiguator), CrateError> {
     info!("find plugin registrar `{}`", name);
     let mut locator = CrateLocator::new(
         sess,
@@ -816,7 +816,7 @@ fn find_plugin_registrar_impl<'a>(
 
     match locator.maybe_load_library_crate()? {
         Some(library) => match library.source.dylib {
-            Some(dylib) => Ok((dylib.0, library.metadata.get_root().stable_crate_id())),
+            Some(dylib) => Ok((dylib.0, library.metadata.get_root().disambiguator())),
             None => Err(CrateError::NonDylibPlugin(name)),
         },
         None => Err(locator.into_error()),

compiler/rustc_metadata/src/rmeta/decoder.rs

@@ -620,6 +620,10 @@ impl CrateRoot<'_> {
         self.name
     }
 
+    crate fn disambiguator(&self) -> CrateDisambiguator {
+        self.disambiguator
+    }
+
     crate fn hash(&self) -> Svh {
         self.hash
     }
@@ -1923,8 +1927,8 @@ impl CrateMetadata {
         self.root.name
     }
 
-    crate fn stable_crate_id(&self) -> StableCrateId {
-        self.root.stable_crate_id
+    crate fn disambiguator(&self) -> CrateDisambiguator {
+        self.root.disambiguator
     }
 
     crate fn hash(&self) -> Svh {

compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs

@@ -19,7 +19,7 @@ use rustc_middle::middle::stability::DeprecationEntry;
 use rustc_middle::ty::query::Providers;
 use rustc_middle::ty::{self, TyCtxt, Visibility};
 use rustc_session::utils::NativeLibKind;
-use rustc_session::{Session, StableCrateId};
+use rustc_session::{CrateDisambiguator, Session};
 use rustc_span::source_map::{Span, Spanned};
 use rustc_span::symbol::Symbol;
 
@@ -186,6 +186,7 @@ provide! { <'tcx> tcx, def_id, other, cdata,
     }
     native_libraries => { Lrc::new(cdata.get_native_libraries(tcx.sess)) }
     foreign_modules => { cdata.get_foreign_modules(tcx) }
+    crate_disambiguator => { cdata.root.disambiguator }
     crate_hash => { cdata.root.hash }
     crate_host_hash => { cdata.host_hash }
     crate_name => { cdata.root.name }
@@ -488,8 +489,8 @@ impl CrateStore for CStore {
         self.get_crate_data(cnum).root.name
     }
 
-    fn stable_crate_id_untracked(&self, cnum: CrateNum) -> StableCrateId {
-        self.get_crate_data(cnum).root.stable_crate_id
+    fn crate_disambiguator_untracked(&self, cnum: CrateNum) -> CrateDisambiguator {
+        self.get_crate_data(cnum).root.disambiguator
     }
 
     fn crate_hash_untracked(&self, cnum: CrateNum) -> Svh {

compiler/rustc_metadata/src/rmeta/encoder.rs

@@ -671,6 +671,7 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
             extra_filename: tcx.sess.opts.cg.extra_filename.clone(),
             triple: tcx.sess.opts.target_triple.clone(),
             hash: tcx.crate_hash(LOCAL_CRATE),
+            disambiguator: tcx.sess.local_crate_disambiguator(),
             stable_crate_id: tcx.def_path_hash(LOCAL_CRATE.as_def_id()).stable_crate_id(),
             panic_strategy: tcx.sess.panic_strategy(),
             edition: tcx.sess.edition(),