incr.comp.: Improve debug output for work products.

src/librustc/dep_graph/graph.rs

@@ -157,9 +157,9 @@ impl DepGraph {
     }
 
     #[inline(always)]
-    pub(super) fn register_dep_node_debug_str<F>(&self,
-                                                 dep_node: DepNode,
-                                                 debug_str_gen: F)
+    pub fn register_dep_node_debug_str<F>(&self,
+                                          dep_node: DepNode,
+                                          debug_str_gen: F)
         where F: FnOnce() -> String
     {
         let mut dep_node_debug = self.data.dep_node_debug.borrow_mut();
@@ -206,6 +206,7 @@ impl DepGraph {
 /// previous hash. If it matches up, we can reuse the object file.
 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
 pub struct WorkProduct {
+    pub cgu_name: String,
     /// Extra hash used to decide if work-product is still suitable;
     /// note that this is *not* a hash of the work-product itself.
     /// See documentation on `WorkProduct` type for an example.

src/librustc/session/config.rs

@@ -489,6 +489,12 @@ impl Options {
             self.debugging_opts.query_dep_graph
     }
 
+    #[inline(always)]
+    pub fn enable_dep_node_debug_strs(&self) -> bool {
+        cfg!(debug_assertions) &&
+            (self.debugging_opts.query_dep_graph || self.debugging_opts.incremental_info)
+    }
+
     pub fn single_codegen_unit(&self) -> bool {
         self.incremental.is_none() ||
         self.cg.codegen_units == 1

src/librustc_incremental/persist/load.rs

@@ -189,7 +189,8 @@ pub fn decode_dep_graph<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
                          &serialized_dep_graph.nodes,
                          &dirty_raw_nodes,
                          &mut clean_work_products,
-                         &mut dirty_work_products);
+                         &mut dirty_work_products,
+                         &work_products);
         }
     }
 
@@ -394,7 +395,8 @@ fn process_edge<'a, 'tcx, 'edges>(
     nodes: &IndexVec<DepNodeIndex, DepNode>,
     dirty_raw_nodes: &DirtyNodes,
     clean_work_products: &mut FxHashSet<WorkProductId>,
-    dirty_work_products: &mut FxHashSet<WorkProductId>)
+    dirty_work_products: &mut FxHashSet<WorkProductId>,
+    work_products: &[SerializedWorkProduct])
 {
     // If the target is dirty, skip the edge. If this is an edge
     // that targets a work-product, we can print the blame
@@ -418,9 +420,11 @@ fn process_edge<'a, 'tcx, 'edges>(
                         format!("{:?}", blame)
                     };
 
-                    eprintln!("incremental: module {:?} is dirty because {:?} \
-                               changed or was removed",
-                              wp_id,
+                    let wp = work_products.iter().find(|swp| swp.id == wp_id).unwrap();
+
+                    eprintln!("incremental: module {:?} is dirty because \
+                              {:?} changed or was removed",
+                              wp.work_product.cgu_name,
                               blame_str);
                 }
             }

src/librustc_incremental/persist/work_product.rs

@@ -55,6 +55,7 @@ pub fn save_trans_partition(sess: &Session,
     };
 
     let work_product = WorkProduct {
+        cgu_name: cgu_name.to_string(),
         input_hash: partition_hash,
         saved_files: saved_files,
     };

src/librustc_trans/partitioning.rs

@@ -270,6 +270,14 @@ pub fn partition<'a, 'tcx, I>(scx: &SharedCrateContext<'a, 'tcx>,
         (&cgu1.name[..]).cmp(&cgu2.name[..])
     });
 
+    if scx.sess().opts.enable_dep_node_debug_strs() {
+        for cgu in &result {
+            let dep_node = cgu.work_product_dep_node();
+            scx.tcx().dep_graph.register_dep_node_debug_str(dep_node,
+                                                            || cgu.name().to_string());
+        }
+    }
+
     result
 }