Feature gate (Rustc){En,De}codable and bench for crater run

Author: petrochenkov

src/librustc/lint/builtin.rs

@@ -335,6 +335,12 @@ declare_lint! {
      via the module system"
 }
 
+declare_lint! {
+    pub CRATER_RUN,
+    Deny,
+    "crater run"
+}
+
 declare_lint! {
     pub MACRO_EXPANDED_MACRO_EXPORTS_ACCESSED_BY_ABSOLUTE_PATHS,
     Deny,

src/librustc_resolve/macros.rs

@@ -1012,10 +1012,17 @@ impl<'a> Resolver<'a> {
 
     fn check_stability_and_deprecation(&self, ext: &SyntaxExtension, path: &str, span: Span) {
         if let Some(stability) = &ext.stability {
-            if let StabilityLevel::Unstable { reason, issue } = stability.level {
+            if let StabilityLevel::Unstable { .. } = stability.level {
                 let feature = stability.feature;
                 if !self.active_features.contains(&feature) && !span.allows_unstable(feature) {
-                    stability::report_unstable(self.session, feature, reason, issue, span);
+                    if !self.session.opts.debugging_opts.force_unstable_if_unmarked {
+                        self.session.buffer_lint(
+                            lint::builtin::CRATER_RUN,
+                            ast::CRATE_NODE_ID,
+                            span,
+                            &format!("`{}` is unstable", path),
+                        );
+                    }
                 }
             }
             if let Some(depr) = &stability.rustc_depr {

src/libsyntax_ext/deriving/mod.rs

@@ -2,7 +2,7 @@
 
 use rustc_data_structures::sync::Lrc;
 use syntax::ast::{self, MetaItem};
-use syntax::attr::Deprecation;
+use syntax::attr::Stability;
 use syntax::edition::Edition;
 use syntax::ext::base::{Annotatable, ExtCtxt, Resolver, MultiItemModifier};
 use syntax::ext::base::{SyntaxExtension, SyntaxExtensionKind};
@@ -61,7 +61,7 @@ impl MultiItemModifier for BuiltinDerive {
 }
 
 macro_rules! derive_traits {
-    ($( [$deprecation:expr] $name:ident => $func:path, )+) => {
+    ($( [$stability:expr] $name:ident => $func:path, )+) => {
         pub fn is_builtin_trait(name: ast::Name) -> bool {
             match name {
                 $( sym::$name )|+ => true,
@@ -82,10 +82,7 @@ macro_rules! derive_traits {
                 resolver.add_builtin(
                     ast::Ident::with_empty_ctxt(sym::$name),
                     Lrc::new(SyntaxExtension {
-                        deprecation: $deprecation.map(|msg| Deprecation {
-                            since: Some(Symbol::intern("1.0.0")),
-                            note: Some(Symbol::intern(msg)),
-                        }),
+                        stability: $stability,
                         allow_internal_unstable: allow_internal_unstable.clone(),
                         ..SyntaxExtension::default(
                             SyntaxExtensionKind::LegacyDerive(Box::new(BuiltinDerive($func))),
@@ -105,10 +102,14 @@ derive_traits! {
     [None]
     Hash => hash::expand_deriving_hash,
 
-    [None]
+    [Some(Stability::unstable(
+        sym::rustc_private, Some(Symbol::intern("RustcEncodable crater run")), 0
+    ))]
     RustcEncodable => encodable::expand_deriving_rustc_encodable,
 
-    [None]
+    [Some(Stability::unstable(
+        sym::rustc_private, Some(Symbol::intern("RustcDecodable crater run")), 0
+    ))]
     RustcDecodable => decodable::expand_deriving_rustc_decodable,
 
     [None]
@@ -130,9 +131,9 @@ derive_traits! {
     Copy => bounds::expand_deriving_copy,
 
     // deprecated
-    [Some("derive(Encodable) is deprecated in favor of derive(RustcEncodable)")]
+    [Some(Stability::unstable(sym::rustc_private, Some(Symbol::intern("Encodable crater run")), 0))]
     Encodable => encodable::expand_deriving_encodable,
-    [Some("derive(Decodable) is deprecated in favor of derive(RustcDecodable)")]
+    [Some(Stability::unstable(sym::rustc_private, Some(Symbol::intern("Decodable crater run")), 0))]
     Decodable => decodable::expand_deriving_decodable,
 }
 

src/libsyntax_ext/lib.rs

@@ -138,9 +138,16 @@ pub fn register_builtins(resolver: &mut dyn syntax::ext::base::Resolver,
     register(sym::test, SyntaxExtension::default(
         SyntaxExtensionKind::LegacyAttr(Box::new(test::expand_test)), edition
     ));
-    register(sym::bench, SyntaxExtension::default(
-        SyntaxExtensionKind::LegacyAttr(Box::new(test::expand_bench)), edition
-    ));
+    register(sym::bench, SyntaxExtension {
+        stability: Some(Stability::unstable(
+            sym::test,
+            Some(Symbol::intern("bench crater run")),
+            0,
+        )),
+        ..SyntaxExtension::default(
+            SyntaxExtensionKind::LegacyAttr(Box::new(test::expand_bench)), edition
+        )
+    });
 
     // format_args uses `unstable` things internally.
     let allow_internal_unstable = Some([sym::fmt_internals][..].into());