Compute proc_macros in resolutions.

compiler/rustc_resolve/src/lib.rs

@@ -1035,6 +1035,9 @@ pub struct Resolver<'a> {
 
     main_def: Option<MainDefinition>,
     trait_impls: BTreeMap<DefId, Vec<LocalDefId>>,
+    /// A list of proc macro LocalDefIds, written out in the order in which
+    /// they are declared in the static array generated by proc_macro_harness.
+    proc_macros: Vec<NodeId>,
 }
 
 /// Nothing really interesting here; it just provides memory for the rest of the crate.
@@ -1400,6 +1403,7 @@ impl<'a> Resolver<'a> {
             item_generics_num_lifetimes: Default::default(),
             main_def: Default::default(),
             trait_impls: Default::default(),
+            proc_macros: Default::default(),
         };
 
         let root_parent_scope = ParentScope::module(graph_root, &resolver);
@@ -1434,6 +1438,7 @@ impl<'a> Resolver<'a> {
     }
 
     pub fn into_outputs(self) -> ResolverOutputs {
+        let proc_macros = self.proc_macros.iter().map(|id| self.local_def_id(*id)).collect();
         let definitions = self.definitions;
         let visibilities = self.visibilities;
         let extern_crate_map = self.extern_crate_map;
@@ -1458,10 +1463,12 @@ impl<'a> Resolver<'a> {
                 .collect(),
             main_def,
             trait_impls: self.trait_impls,
+            proc_macros,
         }
     }
 
     pub fn clone_outputs(&self) -> ResolverOutputs {
+        let proc_macros = self.proc_macros.iter().map(|id| self.local_def_id(*id)).collect();
         ResolverOutputs {
             definitions: self.definitions.clone(),
             cstore: Box::new(self.cstore().clone()),
@@ -1478,6 +1485,7 @@ impl<'a> Resolver<'a> {
                 .collect(),
             main_def: self.main_def.clone(),
             trait_impls: self.trait_impls.clone(),
+            proc_macros,
         }
     }