resolve: Resolve a few very special in macro namespace

src/librustc_resolve/macros.rs

@@ -1082,6 +1082,7 @@ impl<'a, 'cl> Resolver<'a, 'cl> {
                 self.define(module, ident, MacroNS,
                             (def, vis, item.span, expansion, IsMacroExport));
             } else {
+                self.check_reserved_macro_name(ident, MacroNS);
                 self.unused_macros.insert(def_id);
             }
         } else {

src/librustc_resolve/resolve_imports.rs

@@ -454,13 +454,24 @@ impl<'a, 'crateloader> Resolver<'a, 'crateloader> {
         })
     }
 
+    crate fn check_reserved_macro_name(&self, ident: Ident, ns: Namespace) {
+        // Reserve some names that are not quite covered by the general check
+        // performed on `Resolver::builtin_attrs`.
+        if ns == MacroNS &&
+           (ident.name == "cfg" || ident.name == "cfg_attr" || ident.name == "derive") {
+            self.session.span_err(ident.span,
+                                  &format!("name `{}` is reserved in macro namespace", ident));
+        }
+    }
+
     // Define the name or return the existing binding if there is a collision.
     pub fn try_define(&mut self,
                       module: Module<'a>,
                       ident: Ident,
                       ns: Namespace,
                       binding: &'a NameBinding<'a>)
                       -> Result<(), &'a NameBinding<'a>> {
+        self.check_reserved_macro_name(ident, ns);
         self.update_resolution(module, ident, ns, |this, resolution| {
             if let Some(old_binding) = resolution.binding {
                 if binding.is_glob_import() {

src/test/ui/macros/ambiguous-builtin-attrs.rs

@@ -1,4 +1,6 @@
-#![feature(decl_macro)]
+#![feature(decl_macro)] //~ ERROR `feature` is ambiguous
+
+macro feature() {}
 
 macro repr() {}
 
@@ -7,21 +9,21 @@ struct S;
 #[cfg_attr(all(), repr(C))] //~ ERROR `repr` is ambiguous
 struct SCond;
 
-macro cfg() {}
+macro cfg() {} //~ ERROR name `cfg` is reserved in macro namespace
 
 #[cfg(all())] //~ ERROR `cfg` is ambiguous
 struct A;
 #[cfg(any())] // ERROR FIXME
 struct A;
 
-macro cfg_attr() {}
+macro cfg_attr() {} //~ ERROR name `cfg_attr` is reserved in macro namespace
 
 #[cfg_attr(all(), cold)] // ERROR FIXME
 fn g() {}
 #[cfg_attr(any(), cold)] // ERROR FIXME
 fn h() {}
 
-macro derive() {}
+macro derive() {} //~ ERROR name `derive` is reserved in macro namespace
 
 #[derive(Clone)] // ERROR FIXME
 struct B;
@@ -43,4 +45,11 @@ fn f() {}
 #[cfg_attr(all(), inline)] //~ ERROR `inline` is ambiguous
 fn f_cond() {}
 
+fn non_macro_expanded_location<#[inline] T>() { //~ ERROR `inline` is ambiguous
+    match 0u8 {
+        #[repr(C)] //~ ERROR `repr` is ambiguous
+        _ => {}
+    }
+}
+
 fn main() {}

src/test/ui/macros/ambiguous-builtin-attrs.stderr

@@ -1,88 +1,157 @@
+error: name `cfg` is reserved in macro namespace
+  --> $DIR/ambiguous-builtin-attrs.rs:12:7
+   |
+LL | macro cfg() {} //~ ERROR name `cfg` is reserved in macro namespace
+   |       ^^^
+
+error: name `cfg_attr` is reserved in macro namespace
+  --> $DIR/ambiguous-builtin-attrs.rs:19:7
+   |
+LL | macro cfg_attr() {} //~ ERROR name `cfg_attr` is reserved in macro namespace
+   |       ^^^^^^^^
+
+error: name `derive` is reserved in macro namespace
+  --> $DIR/ambiguous-builtin-attrs.rs:26:7
+   |
+LL | macro derive() {} //~ ERROR name `derive` is reserved in macro namespace
+   |       ^^^^^^
+
 error[E0659]: `repr` is ambiguous
-  --> $DIR/ambiguous-builtin-attrs.rs:5:3
+  --> $DIR/ambiguous-builtin-attrs.rs:7:3
    |
 LL | #[repr(C)] //~ ERROR `repr` is ambiguous
    |   ^^^^
    |
 note: `repr` could refer to the name defined here
-  --> $DIR/ambiguous-builtin-attrs.rs:3:1
+  --> $DIR/ambiguous-builtin-attrs.rs:5:1
    |
 LL | macro repr() {}
    | ^^^^^^^^^^^^^^^
 note: `repr` could also refer to the name defined here
-  --> $DIR/ambiguous-builtin-attrs.rs:5:3
+  --> $DIR/ambiguous-builtin-attrs.rs:7:3
    |
 LL | #[repr(C)] //~ ERROR `repr` is ambiguous
    |   ^^^^
 
 error[E0659]: `repr` is ambiguous
-  --> $DIR/ambiguous-builtin-attrs.rs:7:19
+  --> $DIR/ambiguous-builtin-attrs.rs:9:19
    |
 LL | #[cfg_attr(all(), repr(C))] //~ ERROR `repr` is ambiguous
    |                   ^^^^
    |
 note: `repr` could refer to the name defined here
-  --> $DIR/ambiguous-builtin-attrs.rs:3:1
+  --> $DIR/ambiguous-builtin-attrs.rs:5:1
    |
 LL | macro repr() {}
    | ^^^^^^^^^^^^^^^
 note: `repr` could also refer to the name defined here
-  --> $DIR/ambiguous-builtin-attrs.rs:7:19
+  --> $DIR/ambiguous-builtin-attrs.rs:9:19
    |
 LL | #[cfg_attr(all(), repr(C))] //~ ERROR `repr` is ambiguous
    |                   ^^^^
 
 error[E0659]: `cfg` is ambiguous
-  --> $DIR/ambiguous-builtin-attrs.rs:12:3
+  --> $DIR/ambiguous-builtin-attrs.rs:14:3
    |
 LL | #[cfg(all())] //~ ERROR `cfg` is ambiguous
    |   ^^^
    |
 note: `cfg` could refer to the name defined here
-  --> $DIR/ambiguous-builtin-attrs.rs:10:1
+  --> $DIR/ambiguous-builtin-attrs.rs:12:1
    |
-LL | macro cfg() {}
+LL | macro cfg() {} //~ ERROR name `cfg` is reserved in macro namespace
    | ^^^^^^^^^^^^^^
 note: `cfg` could also refer to the name defined here
-  --> $DIR/ambiguous-builtin-attrs.rs:12:3
+  --> $DIR/ambiguous-builtin-attrs.rs:14:3
    |
 LL | #[cfg(all())] //~ ERROR `cfg` is ambiguous
    |   ^^^
 
 error[E0659]: `inline` is ambiguous
-  --> $DIR/ambiguous-builtin-attrs.rs:41:3
+  --> $DIR/ambiguous-builtin-attrs.rs:43:3
    |
 LL | #[inline] //~ ERROR `inline` is ambiguous
    |   ^^^^^^
    |
 note: `inline` could refer to the name defined here
-  --> $DIR/ambiguous-builtin-attrs.rs:39:1
+  --> $DIR/ambiguous-builtin-attrs.rs:41:1
    |
 LL | macro_rules! inline { () => () }
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 note: `inline` could also refer to the name defined here
-  --> $DIR/ambiguous-builtin-attrs.rs:41:3
+  --> $DIR/ambiguous-builtin-attrs.rs:43:3
    |
 LL | #[inline] //~ ERROR `inline` is ambiguous
    |   ^^^^^^
 
 error[E0659]: `inline` is ambiguous
-  --> $DIR/ambiguous-builtin-attrs.rs:43:19
+  --> $DIR/ambiguous-builtin-attrs.rs:45:19
    |
 LL | #[cfg_attr(all(), inline)] //~ ERROR `inline` is ambiguous
    |                   ^^^^^^
    |
 note: `inline` could refer to the name defined here
-  --> $DIR/ambiguous-builtin-attrs.rs:39:1
+  --> $DIR/ambiguous-builtin-attrs.rs:41:1
    |
 LL | macro_rules! inline { () => () }
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 note: `inline` could also refer to the name defined here
-  --> $DIR/ambiguous-builtin-attrs.rs:43:19
+  --> $DIR/ambiguous-builtin-attrs.rs:45:19
    |
 LL | #[cfg_attr(all(), inline)] //~ ERROR `inline` is ambiguous
    |                   ^^^^^^
 
-error: aborting due to 5 previous errors
+error[E0659]: `inline` is ambiguous
+  --> $DIR/ambiguous-builtin-attrs.rs:48:34
+   |
+LL | fn non_macro_expanded_location<#[inline] T>() { //~ ERROR `inline` is ambiguous
+   |                                  ^^^^^^
+   |
+note: `inline` could refer to the name defined here
+  --> $DIR/ambiguous-builtin-attrs.rs:41:1
+   |
+LL | macro_rules! inline { () => () }
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+note: `inline` could also refer to the name defined here
+  --> $DIR/ambiguous-builtin-attrs.rs:48:34
+   |
+LL | fn non_macro_expanded_location<#[inline] T>() { //~ ERROR `inline` is ambiguous
+   |                                  ^^^^^^
+
+error[E0659]: `repr` is ambiguous
+  --> $DIR/ambiguous-builtin-attrs.rs:50:11
+   |
+LL |         #[repr(C)] //~ ERROR `repr` is ambiguous
+   |           ^^^^
+   |
+note: `repr` could refer to the name defined here
+  --> $DIR/ambiguous-builtin-attrs.rs:5:1
+   |
+LL | macro repr() {}
+   | ^^^^^^^^^^^^^^^
+note: `repr` could also refer to the name defined here
+  --> $DIR/ambiguous-builtin-attrs.rs:50:11
+   |
+LL |         #[repr(C)] //~ ERROR `repr` is ambiguous
+   |           ^^^^
+
+error[E0659]: `feature` is ambiguous
+  --> $DIR/ambiguous-builtin-attrs.rs:1:4
+   |
+LL | #![feature(decl_macro)] //~ ERROR `feature` is ambiguous
+   |    ^^^^^^^
+   |
+note: `feature` could refer to the name defined here
+  --> $DIR/ambiguous-builtin-attrs.rs:3:1
+   |
+LL | macro feature() {}
+   | ^^^^^^^^^^^^^^^^^^
+note: `feature` could also refer to the name defined here
+  --> $DIR/ambiguous-builtin-attrs.rs:1:4
+   |
+LL | #![feature(decl_macro)] //~ ERROR `feature` is ambiguous
+   |    ^^^^^^^
+
+error: aborting due to 11 previous errors
 
 For more information about this error, try `rustc --explain E0659`.