Feature gate rustc attributes harder

src/librustc_resolve/macros.rs

@@ -19,9 +19,8 @@ use syntax::ext::base::{MacroKind, SyntaxExtension};
 use syntax::ext::expand::{AstFragment, Invocation, InvocationKind};
 use syntax::ext::hygiene::Mark;
 use syntax::ext::tt::macro_rules;
-use syntax::feature_gate::{
-    feature_err, is_builtin_attr_name, AttributeGate, GateIssue, Stability, BUILTIN_ATTRIBUTES,
-};
+use syntax::feature_gate::{feature_err, emit_feature_err, is_builtin_attr_name};
+use syntax::feature_gate::{AttributeGate, GateIssue, Stability, BUILTIN_ATTRIBUTES};
 use syntax::symbol::{Symbol, kw, sym};
 use syntax::visit::Visitor;
 use syntax::util::lev_distance::find_best_match_for_name;
@@ -298,12 +297,25 @@ impl<'a> Resolver<'a> {
         let res = self.resolve_macro_to_res_inner(path, kind, parent_scope, trace, force);
 
         // Report errors and enforce feature gates for the resolved macro.
+        let features = self.session.features_untracked();
         if res != Err(Determinacy::Undetermined) {
             // Do not report duplicated errors on every undetermined resolution.
             for segment in &path.segments {
                 if let Some(args) = &segment.args {
                     self.session.span_err(args.span(), "generic arguments in macro path");
                 }
+                if kind == MacroKind::Attr && !features.rustc_attrs &&
+                   segment.ident.as_str().starts_with("rustc") {
+                    let msg = "attributes starting with `rustc` are \
+                               reserved for use by the `rustc` compiler";
+                    emit_feature_err(
+                        &self.session.parse_sess,
+                        sym::rustc_attrs,
+                        segment.ident.span,
+                        GateIssue::Language,
+                        msg,
+                    );
+                }
             }
         }
 
@@ -320,18 +332,10 @@ impl<'a> Resolver<'a> {
             }
             Res::NonMacroAttr(attr_kind) => {
                 if kind == MacroKind::Attr {
-                    let features = self.session.features_untracked();
                     if attr_kind == NonMacroAttrKind::Custom {
                         assert!(path.segments.len() == 1);
                         let name = path.segments[0].ident.as_str();
-                        if name.starts_with("rustc_") {
-                            if !features.rustc_attrs {
-                                let msg = "unless otherwise specified, attributes with the prefix \
-                                           `rustc_` are reserved for internal compiler diagnostics";
-                                self.report_unknown_attribute(path.span, &name, msg,
-                                                              sym::rustc_attrs);
-                            }
-                        } else if !features.custom_attribute {
+                        if !features.custom_attribute && !name.starts_with("rustc_") {
                             let msg = format!("The attribute `{}` is currently unknown to the \
                                                compiler and may have meaning added to it in the \
                                                future", path);

src/libsyntax/feature_gate.rs

@@ -1637,6 +1637,14 @@ impl<'a> Context<'a> {
             }
             debug!("check_attribute: {:?} is builtin, {:?}, {:?}", attr.path, ty, gateage);
             return;
+        } else {
+            for segment in &attr.path.segments {
+                if segment.ident.as_str().starts_with("rustc") {
+                    let msg = "attributes starting with `rustc` are \
+                               reserved for use by the `rustc` compiler";
+                    gate_feature!(self, rustc_attrs, segment.ident.span, msg);
+                }
+            }
         }
         for &(n, ty) in self.plugin_attributes {
             if attr.path == n {
@@ -1648,11 +1656,7 @@ impl<'a> Context<'a> {
             }
         }
         if !attr::is_known(attr) {
-            if attr.name_or_empty().as_str().starts_with("rustc_") {
-                let msg = "unless otherwise specified, attributes with the prefix `rustc_` \
-                           are reserved for internal compiler diagnostics";
-                gate_feature!(self, rustc_attrs, attr.span, msg);
-            } else if !is_macro {
+            if !is_macro && !attr.name_or_empty().as_str().starts_with("rustc_") {
                 // Only run the custom attribute lint during regular feature gate
                 // checking. Macro gating runs before the plugin attributes are
                 // registered, so we skip this in that case.

src/test/ui/consts/min_const_fn/allow_const_fn_ptr_feature_gate.rs

@@ -5,7 +5,7 @@ const fn error(_: fn()) {}
 
 #[stable(feature = "rust1", since = "1.0.0")]
 #[rustc_allow_const_fn_ptr]
-//~^ ERROR unless otherwise specified, attributes with the prefix `rustc_` are reserved
+//~^ ERROR attributes starting with `rustc` are reserved for use by the `rustc` compiler
 const fn compiles(_: fn()) {}
 
 fn main() {}

src/test/ui/consts/min_const_fn/allow_const_fn_ptr_feature_gate.stderr

@@ -1,4 +1,4 @@
-error[E0658]: unless otherwise specified, attributes with the prefix `rustc_` are reserved for internal compiler diagnostics
+error[E0658]: attributes starting with `rustc` are reserved for use by the `rustc` compiler
   --> $DIR/allow_const_fn_ptr_feature_gate.rs:7:3
    |
 LL | #[rustc_allow_const_fn_ptr]

src/test/ui/feature-gates/feature-gate-rustc-attrs.rs

@@ -1,6 +1,6 @@
 // Test that `#[rustc_*]` attributes are gated by `rustc_attrs` feature gate.
 
 #[rustc_foo]
-//~^ ERROR unless otherwise specified, attributes with the prefix `rustc_` are reserved
+//~^ ERROR attributes starting with `rustc` are reserved for use by the `rustc` compiler
 
 fn main() {}

src/test/ui/feature-gates/feature-gate-rustc-attrs.stderr

@@ -1,4 +1,4 @@
-error[E0658]: unless otherwise specified, attributes with the prefix `rustc_` are reserved for internal compiler diagnostics
+error[E0658]: attributes starting with `rustc` are reserved for use by the `rustc` compiler
   --> $DIR/feature-gate-rustc-attrs.rs:3:3
    |
 LL | #[rustc_foo]

src/test/ui/proc-macro/expand-to-unstable-2.rs

@@ -6,7 +6,7 @@
 extern crate derive_unstable_2;
 
 #[derive(Unstable)]
-//~^ ERROR: reserved for internal compiler
+//~^ ERROR attributes starting with `rustc` are reserved for use by the `rustc` compiler
 struct A;
 
 fn main() {

src/test/ui/proc-macro/expand-to-unstable-2.stderr

@@ -1,4 +1,4 @@
-error[E0658]: unless otherwise specified, attributes with the prefix `rustc_` are reserved for internal compiler diagnostics
+error[E0658]: attributes starting with `rustc` are reserved for use by the `rustc` compiler
   --> $DIR/expand-to-unstable-2.rs:8:10
    |
 LL | #[derive(Unstable)]

src/test/ui/reserved/reserved-attr-on-macro.rs

@@ -1,5 +1,5 @@
 #[rustc_attribute_should_be_reserved]
-//~^ ERROR unless otherwise specified, attributes with the prefix `rustc_` are reserved
+//~^ ERROR attributes starting with `rustc` are reserved for use by the `rustc` compiler
 macro_rules! foo {
     () => (());
 }

src/test/ui/reserved/reserved-attr-on-macro.stderr

@@ -1,4 +1,4 @@
-error[E0658]: unless otherwise specified, attributes with the prefix `rustc_` are reserved for internal compiler diagnostics
+error[E0658]: attributes starting with `rustc` are reserved for use by the `rustc` compiler
   --> $DIR/reserved-attr-on-macro.rs:1:3
    |
 LL | #[rustc_attribute_should_be_reserved]

src/test/ui/suggestions/attribute-typos.stderr

@@ -1,4 +1,4 @@
-error[E0658]: unless otherwise specified, attributes with the prefix `rustc_` are reserved for internal compiler diagnostics
+error[E0658]: attributes starting with `rustc` are reserved for use by the `rustc` compiler
   --> $DIR/attribute-typos.rs:11:3
    |
 LL | #[rustc_err]