Require a list of features to allow in allow_internal_unstable

src/liballoc/macros.rs

@@ -34,7 +34,8 @@
 #[cfg(not(test))]
 #[macro_export]
 #[stable(feature = "rust1", since = "1.0.0")]
-#[allow_internal_unstable]
+#[cfg_attr(not(stage0), allow_internal_unstable(box_syntax))]
+#[cfg_attr(stage0, allow_internal_unstable)]
 macro_rules! vec {
     ($elem:expr; $n:expr) => (
         $crate::vec::from_elem($elem, $n)

src/libcore/macros.rs

@@ -1,6 +1,7 @@
 /// Entry point of thread panic, for details, see std::macros
 #[macro_export]
-#[allow_internal_unstable]
+#[cfg_attr(not(stage0), allow_internal_unstable(core_panic, __rust_unstable_column))]
+#[cfg_attr(stage0, allow_internal_unstable)]
 #[stable(feature = "core", since = "1.6.0")]
 macro_rules! panic {
     () => (
@@ -409,7 +410,8 @@ macro_rules! write {
 /// ```
 #[macro_export]
 #[stable(feature = "rust1", since = "1.0.0")]
-#[allow_internal_unstable]
+#[cfg_attr(stage0, allow_internal_unstable)]
+#[cfg_attr(not(stage0), allow_internal_unstable(format_args_nl))]
 macro_rules! writeln {
     ($dst:expr) => (
         write!($dst, "\n")

src/librustc/hir/lowering.rs

@@ -681,13 +681,18 @@ impl<'a> LoweringContext<'a> {
         Ident::with_empty_ctxt(Symbol::gensym(s))
     }
 
-    fn allow_internal_unstable(&self, reason: CompilerDesugaringKind, span: Span) -> Span {
+    fn allow_internal_unstable(
+        &self,
+        reason: CompilerDesugaringKind,
+        span: Span,
+        allow_internal_unstable: Vec<Symbol>,
+    ) -> Span {
         let mark = Mark::fresh(Mark::root());
         mark.set_expn_info(source_map::ExpnInfo {
             call_site: span,
             def_site: Some(span),
             format: source_map::CompilerDesugaring(reason),
-            allow_internal_unstable: true,
+            allow_internal_unstable,
             allow_internal_unsafe: false,
             local_inner_macros: false,
             edition: source_map::hygiene::default_edition(),
@@ -964,7 +969,13 @@ impl<'a> LoweringContext<'a> {
             attrs: ThinVec::new(),
         };
 
-        let unstable_span = self.allow_internal_unstable(CompilerDesugaringKind::Async, span);
+        let unstable_span = self.allow_internal_unstable(
+            CompilerDesugaringKind::Async,
+            span,
+            vec![
+                Symbol::intern("gen_future"),
+            ],
+        );
         let gen_future = self.expr_std_path(
             unstable_span, &["future", "from_generator"], None, ThinVec::new());
         hir::ExprKind::Call(P(gen_future), hir_vec![generator])
@@ -1363,6 +1374,7 @@ impl<'a> LoweringContext<'a> {
         let exist_ty_span = self.allow_internal_unstable(
             CompilerDesugaringKind::ExistentialReturnType,
             span,
+            Vec::new(), // doesn'c actually allow anything unstable
         );
 
         let exist_ty_def_index = self
@@ -3927,8 +3939,13 @@ impl<'a> LoweringContext<'a> {
             }),
             ExprKind::TryBlock(ref body) => {
                 self.with_catch_scope(body.id, |this| {
-                    let unstable_span =
-                        this.allow_internal_unstable(CompilerDesugaringKind::TryBlock, body.span);
+                    let unstable_span = this.allow_internal_unstable(
+                        CompilerDesugaringKind::TryBlock,
+                        body.span,
+                        vec![
+                            Symbol::intern("try_trait"),
+                        ],
+                    );
                     let mut block = this.lower_block(body, true).into_inner();
                     let tail = block.expr.take().map_or_else(
                         || {
@@ -4363,6 +4380,7 @@ impl<'a> LoweringContext<'a> {
                 let desugared_span = self.allow_internal_unstable(
                     CompilerDesugaringKind::ForLoop,
                     head_sp,
+                    Vec::new(),
                 );
 
                 let iter = self.str_to_ident("iter");
@@ -4525,8 +4543,13 @@ impl<'a> LoweringContext<'a> {
                 //                 return Try::from_error(From::from(err)),
                 // }
 
-                let unstable_span =
-                    self.allow_internal_unstable(CompilerDesugaringKind::QuestionMark, e.span);
+                let unstable_span = self.allow_internal_unstable(
+                    CompilerDesugaringKind::QuestionMark,
+                    e.span,
+                    vec![
+                        Symbol::intern("try_trait")
+                    ],
+                );
 
                 // `Try::into_result(<expr>)`
                 let discr = {

src/librustc/middle/stability.rs

@@ -561,11 +561,6 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
     /// deprecated. If the item is indeed deprecated, we will emit a deprecation lint attached to
     /// `id`.
     pub fn eval_stability(self, def_id: DefId, id: Option<NodeId>, span: Span) -> EvalResult {
-        if span.allows_unstable() {
-            debug!("stability: skipping span={:?} since it is internal", span);
-            return EvalResult::Allow;
-        }
-
         let lint_deprecated = |def_id: DefId,
                                id: NodeId,
                                note: Option<Symbol>,
@@ -694,6 +689,10 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
 
         match stability {
             Some(&Stability { level: attr::Unstable { reason, issue }, feature, .. }) => {
+                if span.allows_unstable(&feature.as_str()) {
+                    debug!("stability: skipping span={:?} since it is internal", span);
+                    return EvalResult::Allow;
+                }
                 if self.stability().active_features.contains(&feature) {
                     return EvalResult::Allow;
                 }

src/librustc_allocator/expand.rs

@@ -91,7 +91,9 @@ impl MutVisitor for ExpandAllocatorDirectives<'_> {
             call_site: item.span, // use the call site of the static
             def_site: None,
             format: MacroAttribute(Symbol::intern(name)),
-            allow_internal_unstable: true,
+            allow_internal_unstable: vec![
+                Symbol::intern("rustc_attrs"),
+            ],
             allow_internal_unsafe: false,
             local_inner_macros: false,
             edition: hygiene::default_edition(),

src/librustc_metadata/creader.rs

@@ -570,7 +570,7 @@ impl<'a> CrateLoader<'a> {
                 ProcMacro::Bang { name, client } => {
                     (name, SyntaxExtension::ProcMacro {
                         expander: Box::new(BangProcMacro { client }),
-                        allow_internal_unstable: false,
+                        allow_internal_unstable: Vec::new(),
                         edition: root.edition,
                     })
                 }

src/librustc_metadata/cstore_impl.rs

@@ -425,7 +425,9 @@ impl cstore::CStore {
             let client = proc_macro::bridge::client::Client::expand1(proc_macro::quote);
             let ext = SyntaxExtension::ProcMacro {
                 expander: Box::new(BangProcMacro { client }),
-                allow_internal_unstable: true,
+                allow_internal_unstable: vec![
+                    Symbol::intern("proc_macro_def_site"),
+                ],
                 edition: data.root.edition,
             };
             return LoadedMacro::ProcMacro(Lrc::new(ext));

src/librustc_mir/transform/qualify_consts.rs

@@ -907,7 +907,7 @@ impl<'a, 'tcx> Visitor<'tcx> for Qualifier<'a, 'tcx, 'tcx> {
                                     // Check `#[unstable]` const fns or `#[rustc_const_unstable]`
                                     // functions without the feature gate active in this crate in
                                     // order to report a better error message than the one below.
-                                    if self.span.allows_unstable() {
+                                    if self.span.allows_unstable(&feature.as_str()) {
                                         // `allow_internal_unstable` can make such calls stable.
                                         is_const_fn = true;
                                     } else {

src/librustc_plugin/registry.rs

@@ -110,8 +110,8 @@ impl<'a> Registry<'a> {
                     edition,
                 }
             }
-            IdentTT(ext, _, allow_internal_unstable) => {
-                IdentTT(ext, Some(self.krate_span), allow_internal_unstable)
+            IdentTT { ext, span: _, allow_internal_unstable } => {
+                IdentTT { ext, span: Some(self.krate_span), allow_internal_unstable }
             }
             _ => extension,
         }));
@@ -126,7 +126,7 @@ impl<'a> Registry<'a> {
         self.register_syntax_extension(Symbol::intern(name), NormalTT {
             expander: Box::new(expander),
             def_info: None,
-            allow_internal_unstable: false,
+            allow_internal_unstable: Vec::new(),
             allow_internal_unsafe: false,
             local_inner_macros: false,
             unstable_feature: None,

src/libstd/macros.rs

@@ -53,7 +53,8 @@
 /// ```
 #[macro_export]
 #[stable(feature = "rust1", since = "1.0.0")]
-#[allow_internal_unstable]
+#[cfg_attr(stage0, allow_internal_unstable)]
+#[cfg_attr(not(stage0), allow_internal_unstable(__rust_unstable_column, libstd_sys_internals))]
 macro_rules! panic {
     () => ({
         panic!("explicit panic")
@@ -111,7 +112,8 @@ macro_rules! panic {
 /// ```
 #[macro_export]
 #[stable(feature = "rust1", since = "1.0.0")]
-#[allow_internal_unstable]
+#[cfg_attr(stage0, allow_internal_unstable)]
+#[cfg_attr(not(stage0), allow_internal_unstable(print_internals))]
 macro_rules! print {
     ($($arg:tt)*) => ($crate::io::_print(format_args!($($arg)*)));
 }
@@ -143,7 +145,8 @@ macro_rules! print {
 /// ```
 #[macro_export]
 #[stable(feature = "rust1", since = "1.0.0")]
-#[allow_internal_unstable]
+#[cfg_attr(stage0, allow_internal_unstable)]
+#[cfg_attr(not(stage0), allow_internal_unstable(print_internals, format_args_nl))]
 macro_rules! println {
     () => (print!("\n"));
     ($($arg:tt)*) => ({
@@ -174,7 +177,8 @@ macro_rules! println {
 /// ```
 #[macro_export]
 #[stable(feature = "eprint", since = "1.19.0")]
-#[allow_internal_unstable]
+#[cfg_attr(stage0, allow_internal_unstable)]
+#[cfg_attr(not(stage0), allow_internal_unstable(print_internals))]
 macro_rules! eprint {
     ($($arg:tt)*) => ($crate::io::_eprint(format_args!($($arg)*)));
 }
@@ -202,7 +206,8 @@ macro_rules! eprint {
 /// ```
 #[macro_export]
 #[stable(feature = "eprint", since = "1.19.0")]
-#[allow_internal_unstable]
+#[cfg_attr(stage0, allow_internal_unstable)]
+#[cfg_attr(not(stage0), allow_internal_unstable(print_internals, format_args_nl))]
 macro_rules! eprintln {
     () => (eprint!("\n"));
     ($($arg:tt)*) => ({
@@ -325,7 +330,8 @@ macro_rules! dbg {
 /// A macro to await on an async call.
 #[macro_export]
 #[unstable(feature = "await_macro", issue = "50547")]
-#[allow_internal_unstable]
+#[cfg_attr(stage0, allow_internal_unstable)]
+#[cfg_attr(not(stage0), allow_internal_unstable(gen_future, generators))]
 #[allow_internal_unsafe]
 macro_rules! await {
     ($e:expr) => { {

src/libstd/thread/local.rs

@@ -126,7 +126,8 @@ impl<T: 'static> fmt::Debug for LocalKey<T> {
 /// [`std::thread::LocalKey`]: ../std/thread/struct.LocalKey.html
 #[macro_export]
 #[stable(feature = "rust1", since = "1.0.0")]
-#[allow_internal_unstable]
+#[cfg_attr(stage0, allow_internal_unstable)]
+#[cfg_attr(not(stage0), allow_internal_unstable(thread_local_internals))]
 macro_rules! thread_local {
     // empty (base case for the recursion)
     () => {};
@@ -148,7 +149,10 @@ macro_rules! thread_local {
            reason = "should not be necessary",
            issue = "0")]
 #[macro_export]
-#[allow_internal_unstable]
+#[cfg_attr(stage0, allow_internal_unstable)]
+#[cfg_attr(not(stage0), allow_internal_unstable(
+    thread_local_internals, cfg_target_thread_local, thread_local,
+))]
 #[allow_internal_unsafe]
 macro_rules! __thread_local_inner {
     (@key $(#[$attr:meta])* $vis:vis $name:ident, $t:ty, $init:expr) => {

src/libsyntax/ext/base.rs

@@ -621,7 +621,8 @@ pub enum SyntaxExtension {
     /// A function-like procedural macro. TokenStream -> TokenStream.
     ProcMacro {
         expander: Box<dyn ProcMacro + sync::Sync + sync::Send>,
-        allow_internal_unstable: bool,
+        /// Whitelist of unstable features that are treated as stable inside this macro
+        allow_internal_unstable: Vec<Symbol>,
         edition: Edition,
     },
 
@@ -638,8 +639,10 @@ pub enum SyntaxExtension {
         expander: Box<dyn TTMacroExpander + sync::Sync + sync::Send>,
         def_info: Option<(ast::NodeId, Span)>,
         /// Whether the contents of the macro can
-        /// directly use `#[unstable]` things (true == yes).
-        allow_internal_unstable: bool,
+        /// directly use `#[unstable]` things.
+        ///
+        /// Only allows things that require a feature gate in the given whitelist
+        allow_internal_unstable: Vec<Symbol>,
         /// Whether the contents of the macro can use `unsafe`
         /// without triggering the `unsafe_code` lint.
         allow_internal_unsafe: bool,
@@ -654,8 +657,11 @@ pub enum SyntaxExtension {
 
     /// A function-like syntax extension that has an extra ident before
     /// the block.
-    ///
-    IdentTT(Box<dyn IdentMacroExpander + sync::Sync + sync::Send>, Option<Span>, bool),
+    IdentTT {
+        ext: Box<dyn IdentMacroExpander + sync::Sync + sync::Send>,
+        span: Option<Span>,
+        allow_internal_unstable: Vec<Symbol>,
+    },
 
     /// An attribute-like procedural macro. TokenStream -> TokenStream.
     /// The input is the annotated item.
@@ -682,7 +688,7 @@ impl SyntaxExtension {
         match *self {
             SyntaxExtension::DeclMacro { .. } |
             SyntaxExtension::NormalTT { .. } |
-            SyntaxExtension::IdentTT(..) |
+            SyntaxExtension::IdentTT { .. } |
             SyntaxExtension::ProcMacro { .. } =>
                 MacroKind::Bang,
             SyntaxExtension::NonMacroAttr { .. } |
@@ -716,7 +722,7 @@ impl SyntaxExtension {
             SyntaxExtension::ProcMacroDerive(.., edition) => edition,
             // Unstable legacy stuff
             SyntaxExtension::NonMacroAttr { .. } |
-            SyntaxExtension::IdentTT(..) |
+            SyntaxExtension::IdentTT { .. } |
             SyntaxExtension::MultiDecorator(..) |
             SyntaxExtension::MultiModifier(..) |
             SyntaxExtension::BuiltinDerive(..) => hygiene::default_edition(),

src/libsyntax/ext/derive.rs

@@ -58,7 +58,10 @@ pub fn add_derived_markers<T>(cx: &mut ExtCtxt<'_>, span: Span, traits: &[ast::P
         call_site: span,
         def_site: None,
         format: ExpnFormat::MacroAttribute(Symbol::intern(&pretty_name)),
-        allow_internal_unstable: true,
+        allow_internal_unstable: vec![
+            Symbol::intern("rustc_attrs"),
+            Symbol::intern("structural_match"),
+        ],
         allow_internal_unsafe: false,
         local_inner_macros: false,
         edition: hygiene::default_edition(),