1 files changed, 20 insertions, 5 deletions
diff --git a/compiler/rustc_passes/src/lib_features.rs b/compiler/rustc_passes/src/lib_features.rs
index e05994f13..04173c792 100644
--- a/compiler/rustc_passes/src/lib_features.rs
+++ b/compiler/rustc_passes/src/lib_features.rs
@@ -5,6 +5,7 @@
 //! collect them instead.
 
 use rustc_ast::{Attribute, MetaItemKind};
+use rustc_attr::{rust_version_symbol, VERSION_PLACEHOLDER};
 use rustc_errors::struct_span_err;
 use rustc_hir::intravisit::Visitor;
 use rustc_middle::hir::nested_filter;
@@ -29,11 +30,16 @@ impl<'tcx> LibFeatureCollector<'tcx> {
     }
 
     fn extract(&self, attr: &Attribute) -> Option<(Symbol, Option<Symbol>, Span)> {
-        let stab_attrs =
-            [sym::stable, sym::unstable, sym::rustc_const_stable, sym::rustc_const_unstable];
+        let stab_attrs = [
+            sym::stable,
+            sym::unstable,
+            sym::rustc_const_stable,
+            sym::rustc_const_unstable,
+            sym::rustc_default_body_unstable,
+        ];
 
         // Find a stability attribute: one of #[stable(…)], #[unstable(…)],
-        // #[rustc_const_stable(…)], or #[rustc_const_unstable(…)].
+        // #[rustc_const_stable(…)], #[rustc_const_unstable(…)] or #[rustc_default_body_unstable].
         if let Some(stab_attr) = stab_attrs.iter().find(|stab_attr| attr.has_name(**stab_attr)) {
             let meta_kind = attr.meta_kind();
             if let Some(MetaItemKind::List(ref metas)) = meta_kind {
@@ -49,12 +55,21 @@ impl<'tcx> LibFeatureCollector<'tcx> {
                         }
                     }
                 }
+
+                if let Some(s) = since && s.as_str() == VERSION_PLACEHOLDER {
+                    since = Some(rust_version_symbol());
+                }
+
                 if let Some(feature) = feature {
                     // This additional check for stability is to make sure we
                     // don't emit additional, irrelevant errors for malformed
                     // attributes.
-                    let is_unstable =
-                        matches!(*stab_attr, sym::unstable | sym::rustc_const_unstable);
+                    let is_unstable = matches!(
+                        *stab_attr,
+                        sym::unstable
+                            | sym::rustc_const_unstable
+                            | sym::rustc_default_body_unstable
+                    );
                     if since.is_some() || is_unstable {
                         return Some((feature, since, attr.span));
                     }