Unify SourceFile::name_hash and StableSourceFileId

1 files changed, 7 insertions, 48 deletions

diff --git a/compiler/rustc_span/src/source_map.rs b/compiler/rustc_span/src/source_map.rs
index cb10e6bf2ba..c61dbcaae95 100644
--- a/compiler/rustc_span/src/source_map.rs
+++ b/compiler/rustc_span/src/source_map.rs
@@ -13,7 +13,6 @@ use crate::*;
 use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::sync::{IntoDynSyncSend, MappedReadGuard, ReadGuard, RwLock};
 use std::fs;
-use std::hash::Hash;
 use std::io::{self, BorrowedBuf, Read};
 use std::path::{self};
 
@@ -152,45 +151,6 @@ impl FileLoader for RealFileLoader {
     }
 }
 
-/// This is a [SourceFile] identifier that is used to correlate source files between
-/// subsequent compilation sessions (which is something we need to do during
-/// incremental compilation).
-///
-/// The [StableSourceFileId] also contains the CrateNum of the crate the source
-/// file was originally parsed for. This way we get two separate entries in
-/// the [SourceMap] if the same file is part of both the local and an upstream
-/// crate. Trying to only have one entry for both cases is problematic because
-/// at the point where we discover that there's a local use of the file in
-/// addition to the upstream one, we might already have made decisions based on
-/// the assumption that it's an upstream file. Treating the two files as
-/// different has no real downsides.
-#[derive(Copy, Clone, PartialEq, Eq, Hash, Encodable, Decodable, Debug)]
-pub struct StableSourceFileId {
-    /// A hash of the source file's [`FileName`]. This is hash so that it's size
-    /// is more predictable than if we included the actual [`FileName`] value.
-    pub file_name_hash: Hash64,
-
-    /// The [`CrateNum`] of the crate this source file was originally parsed for.
-    /// We cannot include this information in the hash because at the time
-    /// of hashing we don't have the context to map from the [`CrateNum`]'s numeric
-    /// value to a `StableCrateId`.
-    pub cnum: CrateNum,
-}
-
-// FIXME: we need a more globally consistent approach to the problem solved by
-// StableSourceFileId, perhaps built atop source_file.name_hash.
-impl StableSourceFileId {
-    pub fn new(source_file: &SourceFile) -> StableSourceFileId {
-        StableSourceFileId::new_from_name(&source_file.name, source_file.cnum)
-    }
-
-    fn new_from_name(name: &FileName, cnum: CrateNum) -> StableSourceFileId {
-        let mut hasher = StableHasher::new();
-        name.hash(&mut hasher);
-        StableSourceFileId { file_name_hash: hasher.finish(), cnum }
-    }
-}
-
 // _____________________________________________________________________________
 // SourceMap
 //
@@ -320,17 +280,17 @@ impl SourceMap {
         // be empty, so the working directory will be used.
         let (filename, _) = self.path_mapping.map_filename_prefix(&filename);
 
-        let file_id = StableSourceFileId::new_from_name(&filename, LOCAL_CRATE);
-        match self.source_file_by_stable_id(file_id) {
+        let stable_id = StableSourceFileId::from_filename_in_current_crate(&filename);
+        match self.source_file_by_stable_id(stable_id) {
             Some(lrc_sf) => Ok(lrc_sf),
             None => {
                 let source_file = SourceFile::new(filename, src, self.hash_kind)?;
 
                 // Let's make sure the file_id we generated above actually matches
                 // the ID we generate for the SourceFile we just created.
-                debug_assert_eq!(StableSourceFileId::new(&source_file), file_id);
+                debug_assert_eq!(source_file.stable_id, stable_id);
 
-                self.register_source_file(file_id, source_file)
+                self.register_source_file(stable_id, source_file)
             }
         }
     }
@@ -343,7 +303,7 @@ impl SourceMap {
         &self,
         filename: FileName,
         src_hash: SourceFileHash,
-        name_hash: Hash128,
+        stable_id: StableSourceFileId,
         source_len: u32,
         cnum: CrateNum,
         file_local_lines: FreezeLock<SourceFileLines>,
@@ -368,12 +328,11 @@ impl SourceMap {
             multibyte_chars,
             non_narrow_chars,
             normalized_pos,
-            name_hash,
+            stable_id,
             cnum,
         };
 
-        let file_id = StableSourceFileId::new(&source_file);
-        self.register_source_file(file_id, source_file)
+        self.register_source_file(stable_id, source_file)
             .expect("not enough address space for imported source file")
     }