resolve: Remove rustc_attrs as a standalone feature gate

Now it only gates specific built-in attributes

Author: petrochenkov

src/librustc_resolve/macros.rs

@@ -20,7 +20,6 @@ use rustc_feature::is_builtin_attr_name;
 use rustc_hir::def::{self, DefKind, NonMacroAttrKind};
 use rustc_hir::def_id;
 use rustc_session::lint::builtin::UNUSED_MACROS;
-use rustc_session::parse::feature_err;
 use rustc_session::Session;
 use rustc_span::edition::Edition;
 use rustc_span::hygiene::{self, ExpnData, ExpnId, ExpnKind};
@@ -397,20 +396,16 @@ impl<'a> Resolver<'a> {
             Err(Determinacy::Undetermined) => return Err(Indeterminate),
         };
 
-        // Report errors and enforce feature gates for the resolved macro.
-        let features = self.session.features_untracked();
+        // Report errors for the resolved macro.
         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";
-                feature_err(&self.session.parse_sess, sym::rustc_attrs, segment.ident.span, msg)
-                    .emit();
+            if kind == MacroKind::Attr && segment.ident.as_str().starts_with("rustc") {
+                self.session.span_err(
+                    segment.ident.span,
+                    "attributes starting with `rustc` are reserved for use by the `rustc` compiler",
+                );
             }
         }
 

src/test/ui-fulldeps/auxiliary/lint-for-crate-rpass.rs

@@ -2,19 +2,19 @@
 
 #![feature(plugin_registrar, rustc_private)]
 #![feature(box_syntax)]
+
 extern crate rustc_driver;
 extern crate rustc_hir;
-extern crate rustc_span;
-#[macro_use]
 extern crate rustc_lint;
+extern crate rustc_span;
 #[macro_use]
 extern crate rustc_session;
 extern crate rustc_ast;
 
+use rustc_ast::attr;
 use rustc_driver::plugin::Registry;
 use rustc_lint::{LateContext, LateLintPass, LintContext, LintPass};
 use rustc_span::symbol::Symbol;
-use rustc_ast::attr;
 
 macro_rules! fake_lint_pass {
     ($struct:ident, $($attr:expr),*) => {
@@ -50,17 +50,17 @@ declare_lint!(CRATE_NOT_GREEN, Warn, "crate not marked with #![crate_green]");
 
 fake_lint_pass! {
     PassOkay,
-    Symbol::intern("rustc_crate_okay")
+    Symbol::intern("crate_okay")
 }
 
 fake_lint_pass! {
     PassRedBlue,
-    Symbol::intern("rustc_crate_red"), Symbol::intern("rustc_crate_blue")
+    Symbol::intern("crate_red"), Symbol::intern("crate_blue")
 }
 
 fake_lint_pass! {
     PassGreyGreen,
-    Symbol::intern("rustc_crate_grey"), Symbol::intern("rustc_crate_green")
+    Symbol::intern("crate_grey"), Symbol::intern("crate_green")
 }
 
 #[plugin_registrar]

src/test/ui-fulldeps/auxiliary/macro-crate-test.rs

@@ -1,23 +1,23 @@
-// run-pass
+// check-pass
 // aux-build:lint-for-crate-rpass.rs
 // ignore-stage1
 // compile-flags: -D crate-not-okay
 
-#![feature(plugin, register_attr, custom_inner_attributes, rustc_attrs)]
+#![feature(plugin, register_attr, custom_inner_attributes)]
 
 #![register_attr(
-    rustc_crate_okay,
-    rustc_crate_blue,
-    rustc_crate_red,
-    rustc_crate_grey,
-    rustc_crate_green,
+    crate_okay,
+    crate_blue,
+    crate_red,
+    crate_grey,
+    crate_green,
 )]
 
 #![plugin(lint_for_crate_rpass)] //~ WARNING compiler plugins are deprecated
-#![rustc_crate_okay]
-#![rustc_crate_blue]
-#![rustc_crate_red]
-#![rustc_crate_grey]
-#![rustc_crate_green]
+#![crate_okay]
+#![crate_blue]
+#![crate_red]
+#![crate_grey]
+#![crate_green]
 
 fn main() {}

src/test/ui-fulldeps/issue-15778-pass.rs

@@ -1,38 +1,32 @@
-error[E0658]: attributes starting with `rustc` are reserved for use by the `rustc` compiler
+error: attributes starting with `rustc` are reserved for use by the `rustc` compiler
   --> $DIR/feature-gate-rustc-attrs.rs:8:3
    |
 LL | #[rustc::unknown]
    |   ^^^^^
-   |
-   = help: add `#![feature(rustc_attrs)]` to the crate attributes to enable
 
 error: expected attribute, found macro `rustc::unknown`
   --> $DIR/feature-gate-rustc-attrs.rs:8:3
    |
 LL | #[rustc::unknown]
    |   ^^^^^^^^^^^^^^ not an attribute
 
-error[E0658]: attributes starting with `rustc` are reserved for use by the `rustc` compiler
+error: attributes starting with `rustc` are reserved for use by the `rustc` compiler
   --> $DIR/feature-gate-rustc-attrs.rs:13:12
    |
 LL | #[unknown::rustc]
    |            ^^^^^
-   |
-   = help: add `#![feature(rustc_attrs)]` to the crate attributes to enable
 
 error: expected attribute, found macro `unknown::rustc`
   --> $DIR/feature-gate-rustc-attrs.rs:13:3
    |
 LL | #[unknown::rustc]
    |   ^^^^^^^^^^^^^^ not an attribute
 
-error[E0658]: attributes starting with `rustc` are reserved for use by the `rustc` compiler
+error: attributes starting with `rustc` are reserved for use by the `rustc` compiler
   --> $DIR/feature-gate-rustc-attrs.rs:20:3
    |
 LL | #[rustc_unknown]
    |   ^^^^^^^^^^^^^
-   |
-   = help: add `#![feature(rustc_attrs)]` to the crate attributes to enable
 
 error: cannot find attribute `rustc_unknown` in this scope
   --> $DIR/feature-gate-rustc-attrs.rs:20:3

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

@@ -0,0 +1,32 @@
+// force-host
+// no-prefer-dynamic
+
+#![deny(unused)]
+#![crate_type = "proc-macro"]
+
+extern crate proc_macro;
+use proc_macro::*;
+
+#[proc_macro_attribute]
+pub fn duplicate(attr: TokenStream, item: TokenStream) -> TokenStream {
+    let mut new_name = Some(attr.into_iter().nth(0).unwrap());
+    let mut encountered_idents = 0;
+    let input = item.to_string();
+    let ret = item
+        .into_iter()
+        .map(move |token| match token {
+            TokenTree::Ident(_) if encountered_idents == 1 => {
+                encountered_idents += 1;
+                new_name.take().unwrap()
+            }
+            TokenTree::Ident(_) => {
+                encountered_idents += 1;
+                token
+            }
+            _ => token,
+        })
+        .collect::<TokenStream>();
+    let mut input_again = input.parse::<TokenStream>().unwrap();
+    input_again.extend(ret);
+    input_again
+}

src/test/ui/proc-macro/auxiliary/duplicate.rs

@@ -1,12 +1,10 @@
-error[E0658]: attributes starting with `rustc` are reserved for use by the `rustc` compiler
+error: attributes starting with `rustc` are reserved for use by the `rustc` compiler
   --> $DIR/expand-to-unstable-2.rs:10:10
    |
 LL | #[derive(Unstable)]
    |          ^^^^^^^^
    |
-   = help: add `#![feature(rustc_attrs)]` to the crate attributes to enable
    = note: this error originates in a derive macro (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: aborting due to previous error
 
-For more information about this error, try `rustc --explain E0658`.

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

@@ -1,36 +1,33 @@
-// check-pass
-// aux-build:macro-crate-test.rs
-// ignore-stage1
+// The duplicate macro will create a copy of the item with the given identifier.
 
-#![feature(rustc_attrs)]
+// check-pass
+// aux-build:duplicate.rs
 
 #[macro_use]
-extern crate macro_crate_test;
-
-// The duplicate macro will create a copy of the item with the given identifier.
+extern crate duplicate;
 
-#[rustc_duplicate(MyCopy)]
+#[duplicate(MyCopy)]
 struct MyStruct {
-    number: i32
+    number: i32,
 }
 
 trait TestTrait {
-    #[rustc_duplicate(TestType2)]
+    #[duplicate(TestType2)]
     type TestType;
 
-    #[rustc_duplicate(required_fn2)]
+    #[duplicate(required_fn2)]
     fn required_fn(&self);
 
-    #[rustc_duplicate(provided_fn2)]
-    fn provided_fn(&self) { }
+    #[duplicate(provided_fn2)]
+    fn provided_fn(&self) {}
 }
 
 impl TestTrait for MyStruct {
-    #[rustc_duplicate(TestType2)]
+    #[duplicate(TestType2)]
     type TestType = f64;
 
-    #[rustc_duplicate(required_fn2)]
-    fn required_fn(&self) { }
+    #[duplicate(required_fn2)]
+    fn required_fn(&self) {}
 }
 
 fn main() {

src/test/ui-fulldeps/macro-crate-multi-decorator.rs renamed to src/test/ui/proc-macro/macro-crate-multi-decorator.rs

@@ -1,10 +1,8 @@
-error[E0658]: attributes starting with `rustc` are reserved for use by the `rustc` compiler
+error: 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]
    |   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = help: add `#![feature(rustc_attrs)]` to the crate attributes to enable
 
 error: cannot determine resolution for the macro `foo`
   --> $DIR/reserved-attr-on-macro.rs:10:5
@@ -22,4 +20,3 @@ LL | #[rustc_attribute_should_be_reserved]
 
 error: aborting due to 3 previous errors
 
-For more information about this error, try `rustc --explain E0658`.

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

@@ -1,10 +1,8 @@
-error[E0658]: attributes starting with `rustc` are reserved for use by the `rustc` compiler
+error: attributes starting with `rustc` are reserved for use by the `rustc` compiler
   --> $DIR/attribute-typos.rs:11:3
    |
 LL | #[rustc_err]
    |   ^^^^^^^^^
-   |
-   = help: add `#![feature(rustc_attrs)]` to the crate attributes to enable
 
 error: cannot find attribute `rustc_err` in this scope
   --> $DIR/attribute-typos.rs:11:3
@@ -31,4 +29,3 @@ LL | #[deprcated]
 
 error: aborting due to 4 previous errors
 
-For more information about this error, try `rustc --explain E0658`.