incr.comp.: Delete orphaned work-products.

src/librustc/dep_graph/graph.rs

@@ -126,6 +126,12 @@ impl DepGraph {
     pub fn work_products(&self) -> Ref<FxHashMap<Arc<WorkProductId>, WorkProduct>> {
         self.data.work_products.borrow()
     }
+
+    /// Access the map of work-products created during the cached run. Only
+    /// used during saving of the dep-graph.
+    pub fn previous_work_products(&self) -> Ref<FxHashMap<Arc<WorkProductId>, WorkProduct>> {
+        self.data.previous_work_products.borrow()
+    }
 }
 
 /// A "work product" is an intermediate result that we save into the

src/librustc_incremental/lib.rs

@@ -57,3 +57,4 @@ pub use persist::save_trans_partition;
 pub use persist::save_work_products;
 pub use persist::in_incr_comp_dir;
 pub use persist::finalize_session_directory;
+pub use persist::delete_workproduct_files;

src/librustc_incremental/persist/load.rs

@@ -18,7 +18,6 @@ use rustc::ty::TyCtxt;
 use rustc_data_structures::fx::{FxHashSet, FxHashMap};
 use rustc_serialize::Decodable as RustcDecodable;
 use rustc_serialize::opaque::Decoder;
-use std::fs;
 use std::path::{Path};
 
 use IncrementalHashesMap;
@@ -29,6 +28,7 @@ use super::dirty_clean;
 use super::hash::*;
 use super::fs::*;
 use super::file_format;
+use super::work_product;
 
 pub type DirtyNodes = FxHashSet<DepNode<DefPathIndex>>;
 
@@ -322,17 +322,7 @@ fn reconcile_work_products<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
 fn delete_dirty_work_product(tcx: TyCtxt,
                              swp: SerializedWorkProduct) {
     debug!("delete_dirty_work_product({:?})", swp);
-    for &(_, ref file_name) in &swp.work_product.saved_files {
-        let path = in_incr_comp_dir_sess(tcx.sess, file_name);
-        match fs::remove_file(&path) {
-            Ok(()) => { }
-            Err(err) => {
-                tcx.sess.warn(
-                    &format!("file-system error deleting outdated file `{}`: {}",
-                             path.display(), err));
-            }
-        }
-    }
+    work_product::delete_workproduct_files(tcx.sess, &swp.work_product);
 }
 
 fn load_prev_metadata_hashes(tcx: TyCtxt,

src/librustc_incremental/persist/mod.rs

@@ -29,3 +29,4 @@ pub use self::load::load_dep_graph;
 pub use self::save::save_dep_graph;
 pub use self::save::save_work_products;
 pub use self::work_product::save_trans_partition;
+pub use self::work_product::delete_workproduct_files;

src/librustc_incremental/persist/save.rs

@@ -30,6 +30,7 @@ use super::preds::*;
 use super::fs::*;
 use super::dirty_clean;
 use super::file_format;
+use super::work_product;
 use calculate_svh::IchHasher;
 
 pub fn save_dep_graph<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
@@ -84,6 +85,31 @@ pub fn save_work_products(sess: &Session) {
     let _ignore = sess.dep_graph.in_ignore();
     let path = work_products_path(sess);
     save_in(sess, path, |e| encode_work_products(sess, e));
+
+    // We also need to clean out old work-products, as not all of them are
+    // deleted during invalidation. Some object files don't change their
+    // content, they are just not needed anymore.
+    let new_work_products = sess.dep_graph.work_products();
+    let previous_work_products = sess.dep_graph.previous_work_products();
+
+    for (id, wp) in previous_work_products.iter() {
+        if !new_work_products.contains_key(id) {
+            work_product::delete_workproduct_files(sess, wp);
+            debug_assert!(wp.saved_files.iter().all(|&(_, ref file_name)| {
+                !in_incr_comp_dir_sess(sess, file_name).exists()
+            }));
+        }
+    }
+
+    // Check that we did not delete one of the current work-products:
+    debug_assert!({
+        new_work_products.iter()
+                         .flat_map(|(_, wp)| wp.saved_files
+                                               .iter()
+                                               .map(|&(_, ref name)| name))
+                         .map(|name| in_incr_comp_dir_sess(sess, name))
+                         .all(|path| path.exists())
+    });
 }
 
 fn save_in<F>(sess: &Session, path_buf: PathBuf, encode: F)

src/librustc_incremental/persist/work_product.rs

@@ -17,6 +17,7 @@ use rustc::session::config::OutputType;
 use rustc::util::fs::link_or_copy;
 use std::path::PathBuf;
 use std::sync::Arc;
+use std::fs as std_fs;
 
 pub fn save_trans_partition(sess: &Session,
                             cgu_name: &str,
@@ -61,3 +62,17 @@ pub fn save_trans_partition(sess: &Session,
 
     sess.dep_graph.insert_work_product(&work_product_id, work_product);
 }
+
+pub fn delete_workproduct_files(sess: &Session, work_product: &WorkProduct) {
+    for &(_, ref file_name) in &work_product.saved_files {
+        let path = in_incr_comp_dir_sess(sess, file_name);
+        match std_fs::remove_file(&path) {
+            Ok(()) => { }
+            Err(err) => {
+                sess.warn(
+                    &format!("file-system error deleting outdated file `{}`: {}",
+                             path.display(), err));
+            }
+        }
+    }
+}