Stabilize uniform_paths

src/librustc/hir/def.rs

@@ -240,7 +240,7 @@ impl CtorKind {
 }
 
 impl NonMacroAttrKind {
-    fn descr(self) -> &'static str {
+    pub fn descr(self) -> &'static str {
         match self {
             NonMacroAttrKind::Builtin => "built-in attribute",
             NonMacroAttrKind::Tool => "tool attribute",

src/librustc_resolve/lib.rs

@@ -67,7 +67,7 @@ use syntax_pos::{Span, DUMMY_SP, MultiSpan};
 use errors::{Applicability, DiagnosticBuilder, DiagnosticId};
 
 use std::cell::{Cell, RefCell};
-use std::{cmp, fmt, iter, ptr};
+use std::{cmp, fmt, iter, mem, ptr};
 use std::collections::BTreeSet;
 use std::mem::replace;
 use rustc_data_structures::ptr_key::PtrKey;
@@ -2375,11 +2375,27 @@ impl<'a> Resolver<'a> {
                 ast::UseTreeKind::Simple(..) if segments.len() == 1 => &[TypeNS, ValueNS][..],
                 _ => &[TypeNS],
             };
+            let report_error = |this: &Self, ns| {
+                let what = if ns == TypeNS { "type parameters" } else { "local variables" };
+                this.session.span_err(ident.span, &format!("imports cannot refer to {}", what));
+            };
+
             for &ns in nss {
-                if let Some(LexicalScopeBinding::Def(..)) =
-                        self.resolve_ident_in_lexical_scope(ident, ns, None, use_tree.prefix.span) {
-                    let what = if ns == TypeNS { "type parameters" } else { "local variables" };
-                    self.session.span_err(ident.span, &format!("imports cannot refer to {}", what));
+                match self.resolve_ident_in_lexical_scope(ident, ns, None, use_tree.prefix.span) {
+                    Some(LexicalScopeBinding::Def(..)) => {
+                        report_error(self, ns);
+                    }
+                    Some(LexicalScopeBinding::Item(binding)) => {
+                        let orig_blacklisted_binding =
+                            mem::replace(&mut self.blacklisted_binding, Some(binding));
+                        if let Some(LexicalScopeBinding::Def(..)) =
+                                self.resolve_ident_in_lexical_scope(ident, ns, None,
+                                                                    use_tree.prefix.span) {
+                            report_error(self, ns);
+                        }
+                        self.blacklisted_binding = orig_blacklisted_binding;
+                    }
+                    None => {}
                 }
             }
         } else if let ast::UseTreeKind::Nested(use_trees) = &use_tree.kind {
@@ -3874,6 +3890,13 @@ impl<'a> Resolver<'a> {
                         module = Some(ModuleOrUniformRoot::Module(next_module));
                         record_segment_def(self, def);
                     } else if def == Def::ToolMod && i + 1 != path.len() {
+                        if binding.is_import() {
+                            self.session.struct_span_err(
+                                ident.span, "cannot use a tool module through an import"
+                            ).span_note(
+                                binding.span, "the tool module imported here"
+                            ).emit();
+                        }
                         let def = Def::NonMacroAttr(NonMacroAttrKind::Tool);
                         return PathResult::NonModule(PathResolution::new(def));
                     } else if def == Def::Err {

src/librustc_resolve/macros.rs

@@ -376,6 +376,7 @@ impl<'a> Resolver<'a> {
                     .push((path, path_span, kind, parent_scope.clone(), def.ok()));
             }
 
+            self.prohibit_imported_non_macro_attrs(None, def.ok(), path_span);
             def
         } else {
             let binding = self.early_resolve_ident_in_lexical_scope(
@@ -390,7 +391,9 @@ impl<'a> Resolver<'a> {
                     .push((path[0].ident, kind, parent_scope.clone(), binding.ok()));
             }
 
-            binding.map(|binding| binding.def())
+            let def = binding.map(|binding| binding.def());
+            self.prohibit_imported_non_macro_attrs(binding.ok(), def.ok(), path_span);
+            def
         }
     }
 
@@ -828,27 +831,23 @@ impl<'a> Resolver<'a> {
             // but its `Def` should coincide with a crate passed with `--extern`
             // (otherwise there would be ambiguity) and we can skip feature error in this case.
             'ok: {
-                if !is_import || self.session.features_untracked().uniform_paths {
+                if !is_import || !rust_2015 {
                     break 'ok;
                 }
                 if ns == TypeNS && use_prelude && self.extern_prelude_get(ident, true).is_some() {
                     break 'ok;
                 }
-                if rust_2015 {
-                    let root_ident = Ident::new(keywords::PathRoot.name(), orig_ident.span);
-                    let root_module = self.resolve_crate_root(root_ident);
-                    if self.resolve_ident_in_module_ext(ModuleOrUniformRoot::Module(root_module),
-                                                        orig_ident, ns, None, false, path_span)
-                                                        .is_ok() {
-                        break 'ok;
-                    }
+                let root_ident = Ident::new(keywords::PathRoot.name(), orig_ident.span);
+                let root_module = self.resolve_crate_root(root_ident);
+                if self.resolve_ident_in_module_ext(ModuleOrUniformRoot::Module(root_module),
+                                                    orig_ident, ns, None, false, path_span)
+                                                    .is_ok() {
+                    break 'ok;
                 }
 
-                let msg = "imports can only refer to extern crate names \
-                           passed with `--extern` on stable channel";
-                let mut err = feature_err(&self.session.parse_sess, "uniform_paths",
-                                          ident.span, GateIssue::Language, msg);
-
+                let msg = "imports can only refer to extern crate names passed with \
+                           `--extern` in macros originating from 2015 edition";
+                let mut err = self.session.struct_span_err(ident.span, msg);
                 let what = self.binding_description(binding, ident,
                                                     flags.contains(Flags::MISC_FROM_PRELUDE));
                 let note_msg = format!("this import refers to {what}", what = what);
@@ -977,6 +976,20 @@ impl<'a> Resolver<'a> {
         }
     }
 
+    fn prohibit_imported_non_macro_attrs(&self, binding: Option<&'a NameBinding<'a>>,
+                                         def: Option<Def>, span: Span) {
+        if let Some(Def::NonMacroAttr(kind)) = def {
+            if kind != NonMacroAttrKind::Tool && binding.map_or(true, |b| b.is_import()) {
+                let msg = format!("cannot use a {} through an import", kind.descr());
+                let mut err = self.session.struct_span_err(span, &msg);
+                if let Some(binding) = binding {
+                    err.span_note(binding.span, &format!("the {} imported here", kind.descr()));
+                }
+                err.emit();
+            }
+        }
+    }
+
     fn suggest_macro_name(&mut self, name: &str, kind: MacroKind,
                           err: &mut DiagnosticBuilder<'a>, span: Span) {
         // First check if this is a locally-defined bang macro.
@@ -1073,17 +1086,21 @@ impl<'a> Resolver<'a> {
             let ident = ident.modern();
             self.macro_names.insert(ident);
             let def = Def::Macro(def_id, MacroKind::Bang);
-            let vis = ty::Visibility::Invisible; // Doesn't matter for legacy bindings
+            let is_macro_export = attr::contains_name(&item.attrs, "macro_export");
+            let vis = if is_macro_export {
+                ty::Visibility::Public
+            } else {
+                ty::Visibility::Restricted(DefId::local(CRATE_DEF_INDEX))
+            };
             let binding = (def, vis, item.span, expansion).to_name_binding(self.arenas);
             self.set_binding_parent_module(binding, self.current_module);
             let legacy_binding = self.arenas.alloc_legacy_binding(LegacyBinding {
                 parent_legacy_scope: *current_legacy_scope, binding, ident
             });
             *current_legacy_scope = LegacyScope::Binding(legacy_binding);
             self.all_macros.insert(ident.name, def);
-            if attr::contains_name(&item.attrs, "macro_export") {
+            if is_macro_export {
                 let module = self.graph_root;
-                let vis = ty::Visibility::Public;
                 self.define(module, ident, MacroNS,
                             (def, vis, item.span, expansion, IsMacroExport));
             } else {

src/librustc_resolve/resolve_imports.rs

@@ -223,6 +223,11 @@ impl<'a> Resolver<'a> {
         }
 
         let check_usable = |this: &mut Self, binding: &'a NameBinding<'a>| {
+            if let Some(blacklisted_binding) = this.blacklisted_binding {
+                if ptr::eq(binding, blacklisted_binding) {
+                    return Err((Determined, Weak::No));
+                }
+            }
             // `extern crate` are always usable for backwards compatibility, see issue #37020,
             // remove this together with `PUB_USE_OF_PRIVATE_EXTERN_CRATE`.
             let usable = this.is_accessible(binding.vis) || binding.is_extern_crate();

src/libsyntax/feature_gate.rs

@@ -440,9 +440,6 @@ declare_features! (
     // support for arbitrary delimited token streams in non-macro attributes
     (active, unrestricted_attribute_tokens, "1.30.0", Some(55208), None),
 
-    // Allows `use x::y;` to resolve through `self::x`, not just `::x`.
-    (active, uniform_paths, "1.30.0", Some(53130), None),
-
     // Allows unsized rvalues at arguments and parameters.
     (active, unsized_locals, "1.30.0", Some(48055), None),
 
@@ -687,6 +684,8 @@ declare_features! (
     (accepted, cfg_attr_multi, "1.33.0", Some(54881), None),
     // Top level or-patterns (`p | q`) in `if let` and `while let`.
     (accepted, if_while_or_patterns, "1.33.0", Some(48215), None),
+    // Allows `use x::y;` to search `x` in the current scope.
+    (accepted, uniform_paths, "1.32.0", Some(53130), None),
 );
 
 // If you change this, please modify `src/doc/unstable-book` as well. You must

src/test/run-pass/uniform-paths/auxiliary/issue-53691.rs

@@ -1,7 +1,5 @@
 // edition:2018
 
-#![feature(uniform_paths)]
-
 mod m { pub fn f() {} }
 mod n { pub fn g() {} }
 

src/test/run-pass/uniform-paths/basic-nested.rs

@@ -1,12 +1,12 @@
-// run-pass
-#![allow(unused_imports)]
-#![allow(non_camel_case_types)]
+// This test is similar to `basic.rs`, but nested in modules.
 
+// run-pass
 // edition:2018
 
-#![feature(decl_macro, uniform_paths)]
+#![feature(decl_macro)]
 
-// This test is similar to `basic.rs`, but nested in modules.
+#![allow(unused_imports)]
+#![allow(non_camel_case_types)]
 
 mod foo {
     // Test that ambiguity errors are not emitted between `self::test` and

src/test/run-pass/uniform-paths/basic.rs

@@ -1,10 +1,8 @@
 // run-pass
-#![allow(unused_imports)]
-#![allow(non_camel_case_types)]
-
 // edition:2018
 
-#![feature(uniform_paths)]
+#![allow(unused_imports)]
+#![allow(non_camel_case_types)]
 
 // Test that ambiguity errors are not emitted between `self::test` and
 // `::test`, assuming the latter (crate) is not in `extern_prelude`.

src/test/run-pass/uniform-paths/macros-nested.rs

@@ -1,11 +1,9 @@
-// run-pass
-#![allow(non_camel_case_types)]
+// This test is similar to `macros.rs`, but nested in modules.
 
+// run-pass
 // edition:2018
 
-#![feature(uniform_paths)]
-
-// This test is similar to `macros.rs`, but nested in modules.
+#![allow(non_camel_case_types)]
 
 mod foo {
     // Test that ambiguity errors are not emitted between `self::test` and

src/test/run-pass/uniform-paths/macros.rs

@@ -1,11 +1,9 @@
-// run-pass
-#![allow(non_camel_case_types)]
+// This test is similar to `basic.rs`, but with macros defining local items.
 
+// run-pass
 // edition:2018
 
-#![feature(uniform_paths)]
-
-// This test is similar to `basic.rs`, but with macros defining local items.
+#![allow(non_camel_case_types)]
 
 // Test that ambiguity errors are not emitted between `self::test` and
 // `::test`, assuming the latter (crate) is not in `extern_prelude`.

src/test/run-pass/uniform-paths/same-crate.rs

@@ -1,9 +1,6 @@
 // run-pass
-
 // edition:2018
 
-#![feature(uniform_paths)]
-
 pub const A: usize = 0;
 
 pub mod foo {

src/test/ui/editions/edition-imports-2015.rs

@@ -3,8 +3,6 @@
 // aux-build:edition-imports-2018.rs
 // aux-build:absolute.rs
 
-#![feature(uniform_paths)]
-
 #[macro_use]
 extern crate edition_imports_2018;
 

src/test/ui/editions/edition-imports-2015.stderr

@@ -1,5 +1,5 @@
 error: cannot glob-import all possible crates
-  --> $DIR/edition-imports-2015.rs:25:5
+  --> $DIR/edition-imports-2015.rs:23:5
    |
 LL |     gen_glob!(); //~ ERROR cannot glob-import all possible crates
    |     ^^^^^^^^^^^^

src/test/ui/editions/edition-imports-virtual-2015-gated.stderr

@@ -1,4 +1,4 @@
-error[E0658]: imports can only refer to extern crate names passed with `--extern` on stable channel (see issue #53130)
+error: imports can only refer to extern crate names passed with `--extern` in macros originating from 2015 edition
   --> <::edition_imports_2015::gen_gated macros>:1:50
    |
 LL | (  ) => { fn check_gated (  ) { enum E { A } use E :: * ; } }
@@ -9,7 +9,6 @@ LL | (  ) => { fn check_gated (  ) { enum E { A } use E :: * ; } }
 LL |     gen_gated!();
    |     ------------- not an extern crate passed with `--extern`
    |
-   = help: add #![feature(uniform_paths)] to the crate attributes to enable
 note: this import refers to the enum defined here
   --> $DIR/edition-imports-virtual-2015-gated.rs:9:5
    |
@@ -19,4 +18,3 @@ LL |     gen_gated!();
 
 error: aborting due to previous error
 
-For more information about this error, try `rustc --explain E0658`.

src/test/ui/imports/issue-56125.rs

@@ -2,8 +2,6 @@
 // compile-flags:--extern issue_56125
 // aux-build:issue-56125.rs
 
-#![feature(uniform_paths)]
-
 mod m1 {
     use issue_56125::last_segment::*;
     //~^ ERROR `issue_56125` is ambiguous