expand: Turn `ast::Crate` into a first class expansion target

And stop creating a fake `mod` item for the crate root when expanding a crate.

2 files changed, 18 insertions, 10 deletions

diff --git a/compiler/rustc_resolve/src/build_reduced_graph.rs b/compiler/rustc_resolve/src/build_reduced_graph.rs
index 3cf9d324a38..26a5260b93f 100644
--- a/compiler/rustc_resolve/src/build_reduced_graph.rs
+++ b/compiler/rustc_resolve/src/build_reduced_graph.rs
@@ -651,11 +651,6 @@ impl<'a, 'b> BuildReducedGraphVisitor<'a, 'b> {
 
     /// Constructs the reduced graph for one item.
     fn build_reduced_graph_for_item(&mut self, item: &'b Item) {
-        if matches!(item.kind, ItemKind::Mod(..)) && item.ident.name == kw::Empty {
-            // Fake crate root item from expand.
-            return;
-        }
-
         let parent_scope = &self.parent_scope;
         let parent = parent_scope.module;
         let expansion = parent_scope.expansion;
@@ -1499,4 +1494,13 @@ impl<'a, 'b> Visitor<'b> for BuildReducedGraphVisitor<'a, 'b> {
 
         visit::walk_variant(self, variant);
     }
+
+    fn visit_crate(&mut self, krate: &'b ast::Crate) {
+        if let Some(id) = krate.is_placeholder {
+            self.visit_invoc_in_module(id);
+        } else {
+            visit::walk_crate(self, krate);
+            self.contains_macro_use(&krate.attrs);
+        }
+    }
 }
diff --git a/compiler/rustc_resolve/src/def_collector.rs b/compiler/rustc_resolve/src/def_collector.rs
index 5879cb1daa5..391baa85c61 100644
--- a/compiler/rustc_resolve/src/def_collector.rs
+++ b/compiler/rustc_resolve/src/def_collector.rs
@@ -7,7 +7,7 @@ use rustc_expand::expand::AstFragment;
 use rustc_hir::def_id::LocalDefId;
 use rustc_hir::definitions::*;
 use rustc_span::hygiene::LocalExpnId;
-use rustc_span::symbol::{kw, sym};
+use rustc_span::symbol::sym;
 use rustc_span::Span;
 use tracing::debug;
 
@@ -92,10 +92,6 @@ impl<'a, 'b> visit::Visitor<'a> for DefCollector<'a, 'b> {
         // information we encapsulate into, the better
         let def_data = match &i.kind {
             ItemKind::Impl { .. } => DefPathData::Impl,
-            ItemKind::Mod(..) if i.ident.name == kw::Empty => {
-                // Fake crate root item from expand.
-                return visit::walk_item(self, i);
-            }
             ItemKind::Mod(..)
             | ItemKind::Trait(..)
             | ItemKind::TraitAlias(..)
@@ -346,4 +342,12 @@ impl<'a, 'b> visit::Visitor<'a> for DefCollector<'a, 'b> {
     fn visit_field_def(&mut self, field: &'a FieldDef) {
         self.collect_field(field, None);
     }
+
+    fn visit_crate(&mut self, krate: &'a Crate) {
+        if let Some(id) = krate.is_placeholder {
+            self.visit_macro_invoc(id)
+        } else {
+            visit::walk_crate(self, krate)
+        }
+    }
 }