Save metadata among work products.

Author: cjgillot

compiler/rustc_interface/src/queries.rs

@@ -45,10 +45,23 @@ impl Linker {
     }
 
     pub fn link(self, sess: &Session, codegen_backend: &dyn CodegenBackend) {
-        let (codegen_results, work_products) = sess.time("finish_ongoing_codegen", || {
+        let (codegen_results, mut work_products) = sess.time("finish_ongoing_codegen", || {
             codegen_backend.join_codegen(self.ongoing_codegen, sess, &self.output_filenames)
         });
 
+        if sess.opts.incremental.is_some()
+            && let Some(path) = self.metadata.path()
+            && let Some((id, product)) =
+                rustc_incremental::copy_cgu_workproduct_to_incr_comp_cache_dir(
+                    sess,
+                    "metadata",
+                    &[("rmeta", path)],
+                    &[],
+                )
+        {
+            work_products.insert(id, product);
+        }
+
         sess.dcx().abort_if_errors();
 
         let _timer = sess.timer("link");

compiler/rustc_metadata/src/rmeta/encoder.rs

@@ -2268,6 +2268,8 @@ pub struct EncodedMetadata {
     // This is an optional stub metadata containing only the crate header.
     // The header should be very small, so we load it directly into memory.
     stub_metadata: Option<Vec<u8>>,
+    // The path containing the metadata, to record as work product.
+    path: Option<Box<Path>>,
     // We need to carry MaybeTempDir to avoid deleting the temporary
     // directory while accessing the Mmap.
     _temp_dir: Option<MaybeTempDir>,
@@ -2283,14 +2285,24 @@ impl EncodedMetadata {
         let file = std::fs::File::open(&path)?;
         let file_metadata = file.metadata()?;
         if file_metadata.len() == 0 {
-            return Ok(Self { full_metadata: None, stub_metadata: None, _temp_dir: None });
+            return Ok(Self {
+                full_metadata: None,
+                stub_metadata: None,
+                path: None,
+                _temp_dir: None,
+            });
         }
         let full_mmap = unsafe { Some(Mmap::map(file)?) };
 
         let stub =
             if let Some(stub_path) = stub_path { Some(std::fs::read(stub_path)?) } else { None };
 
-        Ok(Self { full_metadata: full_mmap, stub_metadata: stub, _temp_dir: temp_dir })
+        Ok(Self {
+            full_metadata: full_mmap,
+            stub_metadata: stub,
+            path: Some(path.into()),
+            _temp_dir: temp_dir,
+        })
     }
 
     #[inline]
@@ -2302,6 +2314,11 @@ impl EncodedMetadata {
     pub fn stub_or_full(&self) -> &[u8] {
         self.stub_metadata.as_deref().unwrap_or(self.full())
     }
+
+    #[inline]
+    pub fn path(&self) -> Option<&Path> {
+        self.path.as_deref()
+    }
 }
 
 impl<S: Encoder> Encodable<S> for EncodedMetadata {
@@ -2326,7 +2343,7 @@ impl<D: Decoder> Decodable<D> for EncodedMetadata {
             None
         };
 
-        Self { full_metadata, stub_metadata: stub, _temp_dir: None }
+        Self { full_metadata, stub_metadata: stub, path: None, _temp_dir: None }
     }
 }