1 files changed, 34 insertions, 25 deletions

diff --git a/compiler/rustc_passes/src/lib_features.rs b/compiler/rustc_passes/src/lib_features.rs
index e05994f13..b5843c0ae 100644
--- a/compiler/rustc_passes/src/lib_features.rs
+++ b/compiler/rustc_passes/src/lib_features.rs
@@ -5,7 +5,7 @@
 //! collect them instead.
 
 use rustc_ast::{Attribute, MetaItemKind};
-use rustc_errors::struct_span_err;
+use rustc_attr::{rust_version_symbol, VERSION_PLACEHOLDER};
 use rustc_hir::intravisit::Visitor;
 use rustc_middle::hir::nested_filter;
 use rustc_middle::middle::lib_features::LibFeatures;
@@ -14,6 +14,8 @@ use rustc_middle::ty::TyCtxt;
 use rustc_span::symbol::Symbol;
 use rustc_span::{sym, Span};
 
+use crate::errors::{FeaturePreviouslyDeclared, FeatureStableTwice};
+
 fn new_lib_features() -> LibFeatures {
     LibFeatures { stable: Default::default(), unstable: Default::default() }
 }
@@ -29,11 +31,16 @@ 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 +56,21 @@ 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));
                     }
@@ -77,14 +93,12 @@ impl<'tcx> LibFeatureCollector<'tcx> {
             (Some(since), _, false) => {
                 if let Some((prev_since, _)) = self.lib_features.stable.get(&feature) {
                     if *prev_since != since {
-                        self.span_feature_error(
+                        self.tcx.sess.emit_err(FeatureStableTwice {
                             span,
-                            &format!(
-                                "feature `{}` is declared stable since {}, \
-                                 but was previously declared stable since {}",
-                                feature, since, prev_since,
-                            ),
-                        );
+                            feature,
+                            since,
+                            prev_since: *prev_since,
+                        });
                         return;
                     }
                 }
@@ -95,22 +109,17 @@ impl<'tcx> LibFeatureCollector<'tcx> {
                 self.lib_features.unstable.insert(feature, span);
             }
             (Some(_), _, true) | (None, true, _) => {
-                self.span_feature_error(
+                let declared = if since.is_some() { "stable" } else { "unstable" };
+                let prev_declared = if since.is_none() { "stable" } else { "unstable" };
+                self.tcx.sess.emit_err(FeaturePreviouslyDeclared {
                     span,
-                    &format!(
-                        "feature `{}` is declared {}, but was previously declared {}",
-                        feature,
-                        if since.is_some() { "stable" } else { "unstable" },
-                        if since.is_none() { "stable" } else { "unstable" },
-                    ),
-                );
+                    feature,
+                    declared,
+                    prev_declared,
+                });
             }
         }
     }
-
-    fn span_feature_error(&self, span: Span, msg: &str) {
-        struct_span_err!(self.tcx.sess, span, E0711, "{}", &msg).emit();
-    }
 }
 
 impl<'tcx> Visitor<'tcx> for LibFeatureCollector<'tcx> {