resolve: Remove unshadowable_attrs

Author: petrochenkov

src/librustc_resolve/lib.rs

@@ -1449,7 +1449,6 @@ pub struct Resolver<'a, 'b: 'a> {
     macro_names: FxHashSet<Ident>,
     builtin_macros: FxHashMap<Name, &'a NameBinding<'a>>,
     macro_use_prelude: FxHashMap<Name, &'a NameBinding<'a>>,
-    unshadowable_attrs: FxHashMap<Name, &'a NameBinding<'a>>,
     pub all_macros: FxHashMap<Name, Def>,
     macro_map: FxHashMap<DefId, Lrc<SyntaxExtension>>,
     macro_defs: FxHashMap<Mark, DefId>,
@@ -1767,7 +1766,6 @@ impl<'a, 'crateloader: 'a> Resolver<'a, 'crateloader> {
             macro_names: FxHashSet(),
             builtin_macros: FxHashMap(),
             macro_use_prelude: FxHashMap(),
-            unshadowable_attrs: FxHashMap(),
             all_macros: FxHashMap(),
             macro_map: FxHashMap(),
             invocations,

src/librustc_resolve/macros.rs

@@ -220,23 +220,6 @@ impl<'a, 'crateloader: 'a> base::Resolver for Resolver<'a, 'crateloader> {
         }
     }
 
-    fn add_unshadowable_attr(&mut self, ident: ast::Ident, ext: Lrc<SyntaxExtension>) {
-        let def_id = DefId {
-            krate: BUILTIN_MACROS_CRATE,
-            index: DefIndex::from_array_index(self.macro_map.len(),
-                                              DefIndexAddressSpace::Low),
-        };
-        let kind = ext.kind();
-        self.macro_map.insert(def_id, ext);
-        let binding = self.arenas.alloc_name_binding(NameBinding {
-            kind: NameBindingKind::Def(Def::Macro(def_id, kind), false),
-            span: DUMMY_SP,
-            vis: ty::Visibility::Invisible,
-            expansion: Mark::root(),
-        });
-        self.unshadowable_attrs.insert(ident.name, binding);
-    }
-
     fn resolve_imports(&mut self) {
         ImportResolver { resolver: self }.resolve_imports()
     }
@@ -493,14 +476,8 @@ impl<'a, 'cl> Resolver<'a, 'cl> {
             return def;
         }
 
-        if kind == MacroKind::Attr {
-            if let Some(ext) = self.unshadowable_attrs.get(&path[0].name) {
-                return Ok(ext.def());
-            }
-        }
-
         let legacy_resolution = self.resolve_legacy_scope(
-            path[0], invoc_id, invocation.parent_legacy_scope.get(), false
+            path[0], invoc_id, invocation.parent_legacy_scope.get(), false, kind == MacroKind::Attr
         );
         let result = if let Some(legacy_binding) = legacy_resolution {
             Ok(legacy_binding.def())
@@ -643,7 +620,19 @@ impl<'a, 'cl> Resolver<'a, 'cl> {
                 }
                 WhereToResolve::MacroUsePrelude => {
                     match self.macro_use_prelude.get(&ident.name).cloned() {
-                        Some(binding) => Ok((binding, FromPrelude(true))),
+                        Some(binding) => {
+                            let mut result = Ok((binding, FromPrelude(true)));
+                            // FIXME: Keep some built-in macros working even if they are
+                            // shadowed by non-attribute macros imported with `macro_use`.
+                            // We need to come up with some more principled approach instead.
+                            if is_attr && (ident.name == "test" || ident.name == "bench") {
+                                if let Def::Macro(_, MacroKind::Bang) =
+                                        binding.def_ignoring_ambiguity() {
+                                    result = Err(Determinacy::Determined);
+                                }
+                            }
+                            result
+                        }
                         None => Err(Determinacy::Determined),
                     }
                 }
@@ -811,8 +800,16 @@ impl<'a, 'cl> Resolver<'a, 'cl> {
                             ident: Ident,
                             invoc_id: Mark,
                             invoc_parent_legacy_scope: LegacyScope<'a>,
-                            record_used: bool)
+                            record_used: bool,
+                            is_attr: bool)
                             -> Option<&'a NameBinding<'a>> {
+        if is_attr && (ident.name == "test" || ident.name == "bench") {
+            // FIXME: Keep some built-in macros working even if they are
+            // shadowed by user-defined `macro_rules`.
+            // We need to come up with some more principled approach instead.
+            return None;
+        }
+
         let ident = ident.modern();
 
         // This is *the* result, resolution from the scope closest to the resolved identifier.
@@ -898,7 +895,7 @@ impl<'a, 'cl> Resolver<'a, 'cl> {
             let span = ident.span;
             let invocation = self.invocations[&invoc_id];
             let legacy_resolution = self.resolve_legacy_scope(
-                ident, invoc_id, invocation.parent_legacy_scope.get(), true
+                ident, invoc_id, invocation.parent_legacy_scope.get(), true, kind == MacroKind::Attr
             );
             let resolution = self.resolve_lexical_macro_path_segment(
                 ident, MacroNS, invoc_id, true, true, kind == MacroKind::Attr, span

src/libsyntax/ext/base.rs

@@ -721,7 +721,6 @@ pub trait Resolver {
     fn visit_ast_fragment_with_placeholders(&mut self, mark: Mark, fragment: &AstFragment,
                                             derives: &[Mark]);
     fn add_builtin(&mut self, ident: ast::Ident, ext: Lrc<SyntaxExtension>);
-    fn add_unshadowable_attr(&mut self, ident: ast::Ident, ext: Lrc<SyntaxExtension>);
 
     fn resolve_imports(&mut self);
     // Resolves attribute and derive legacy macros from `#![plugin(..)]`.
@@ -761,7 +760,6 @@ impl Resolver for DummyResolver {
     fn visit_ast_fragment_with_placeholders(&mut self, _invoc: Mark, _fragment: &AstFragment,
                                             _derives: &[Mark]) {}
     fn add_builtin(&mut self, _ident: ast::Ident, _ext: Lrc<SyntaxExtension>) {}
-    fn add_unshadowable_attr(&mut self, _ident: ast::Ident, _ext: Lrc<SyntaxExtension>) {}
 
     fn resolve_imports(&mut self) {}
     fn find_legacy_attr_invoc(&mut self, _attrs: &mut Vec<Attribute>, _allow_derive: bool)

src/libsyntax_ext/lib.rs

@@ -72,18 +72,6 @@ pub fn register_builtins(resolver: &mut dyn syntax::ext::base::Resolver,
                          enable_quotes: bool) {
     deriving::register_builtin_derives(resolver);
 
-    {
-        let mut register_unshadowable = |name, ext| {
-            resolver.add_unshadowable_attr(ast::Ident::with_empty_ctxt(name), Lrc::new(ext));
-        };
-
-        register_unshadowable(Symbol::intern("test"),
-            MultiModifier(Box::new(test::expand_test)));
-
-        register_unshadowable(Symbol::intern("bench"),
-            MultiModifier(Box::new(test::expand_bench)));
-    }
-
     let mut register = |name, ext| {
         resolver.add_builtin(ast::Ident::with_empty_ctxt(name), Lrc::new(ext));
     };
@@ -147,6 +135,8 @@ pub fn register_builtins(resolver: &mut dyn syntax::ext::base::Resolver,
     }
 
     register(Symbol::intern("test_case"), MultiModifier(Box::new(test_case::expand)));
+    register(Symbol::intern("test"), MultiModifier(Box::new(test::expand_test)));
+    register(Symbol::intern("bench"), MultiModifier(Box::new(test::expand_bench)));
 
     // format_args uses `unstable` things internally.
     register(Symbol::intern("format_args"),

src/test/ui/issues/issue-11692-2.rs

@@ -9,6 +9,5 @@
 // except according to those terms.
 
 fn main() {
-    concat!(test!());
-    //~^ error: cannot find macro `test!` in this scope
+    concat!(test!()); //~ ERROR `test` can only be used in attributes
 }

src/test/ui/issues/issue-11692-2.stderr

@@ -1,7 +1,7 @@
-error: cannot find macro `test!` in this scope
+error: `test` can only be used in attributes
   --> $DIR/issue-11692-2.rs:12:13
    |
-LL |     concat!(test!());
+LL |     concat!(test!()); //~ ERROR `test` can only be used in attributes
    |             ^^^^
 
 error: aborting due to previous error

src/test/ui/test-shadowing/test-cant-be-shadowed.rs

@@ -16,3 +16,8 @@
 
 #[test]
 fn foo(){}
+
+macro_rules! test { () => () }
+
+#[test]
+fn bar() {}