Auto merge of #50911 - petrochenkov:macuse, r=alexcrichton

Stabilize `use_extern_macros`

Closes #35896

Author: bors

src/librustc_resolve/build_reduced_graph.rs

@@ -833,19 +833,12 @@ impl<'a, 'cl> Resolver<'a, 'cl> {
                                     -> bool {
         let allow_shadowing = expansion == Mark::root();
         let legacy_imports = self.legacy_macro_imports(&item.attrs);
-        let mut used = legacy_imports != LegacyMacroImports::default();
+        let used = legacy_imports != LegacyMacroImports::default();
 
         // `#[macro_use]` is only allowed at the crate root.
         if self.current_module.parent.is_some() && used {
             span_err!(self.session, item.span, E0468,
                       "an `extern crate` loading macros must be at the crate root");
-        } else if !self.use_extern_macros && !used &&
-                  self.cstore.dep_kind_untracked(module.def_id().unwrap().krate)
-                      .macros_only() {
-            let msg = "proc macro crates and `#[no_link]` crates have no effect without \
-                       `#[macro_use]`";
-            self.session.span_warn(item.span, msg);
-            used = true; // Avoid the normal unused extern crate warning
         }
 
         let (graph_root, arenas) = (self.graph_root, self.arenas);

src/librustc_resolve/check_unused.rs

@@ -131,7 +131,7 @@ pub fn check_crate(resolver: &mut Resolver, krate: &ast::Crate) {
                  directive.vis.get() == ty::Visibility::Public ||
                  directive.span.is_dummy() => {
                 if let ImportDirectiveSubclass::MacroUse = directive.subclass {
-                    if resolver.use_extern_macros && !directive.span.is_dummy() {
+                    if !directive.span.is_dummy() {
                         resolver.session.buffer_lint(
                             lint::builtin::MACRO_USE_EXTERN_CRATE,
                             directive.id,

src/librustc_resolve/lib.rs

@@ -80,7 +80,7 @@ use std::mem::replace;
 use rustc_data_structures::sync::Lrc;
 
 use resolve_imports::{ImportDirective, ImportDirectiveSubclass, NameResolution, ImportResolver};
-use macros::{InvocationData, LegacyBinding, LegacyScope, MacroBinding};
+use macros::{InvocationData, LegacyBinding, MacroBinding};
 
 // NB: This module needs to be declared first so diagnostics are
 // registered before they are used.
@@ -1399,23 +1399,18 @@ pub struct Resolver<'a, 'b: 'a> {
     /// crate-local macro expanded `macro_export` referred to by a module-relative path
     macro_expanded_macro_export_errors: BTreeSet<(Span, Span)>,
 
-    gated_errors: FxHashSet<Span>,
     disallowed_shadowing: Vec<&'a LegacyBinding<'a>>,
 
     arenas: &'a ResolverArenas<'a>,
     dummy_binding: &'a NameBinding<'a>,
-    /// true if `#![feature(use_extern_macros)]`
-    use_extern_macros: bool,
 
     crate_loader: &'a mut CrateLoader<'b>,
     macro_names: FxHashSet<Ident>,
     macro_prelude: FxHashMap<Name, &'a NameBinding<'a>>,
     pub all_macros: FxHashMap<Name, Def>,
-    lexical_macro_resolutions: Vec<(Ident, &'a Cell<LegacyScope<'a>>)>,
     macro_map: FxHashMap<DefId, Lrc<SyntaxExtension>>,
     macro_defs: FxHashMap<Mark, DefId>,
     local_macro_def_scopes: FxHashMap<NodeId, Module<'a>>,
-    macro_exports: Vec<Export>, // FIXME: Remove when `use_extern_macros` is stabilized
     pub whitelisted_legacy_custom_derives: Vec<Name>,
     pub found_unresolved_macro: bool,
 
@@ -1657,8 +1652,6 @@ impl<'a, 'crateloader: 'a> Resolver<'a, 'crateloader> {
         invocations.insert(Mark::root(),
                            arenas.alloc_invocation_data(InvocationData::root(graph_root)));
 
-        let features = session.features_untracked();
-
         let mut macro_defs = FxHashMap();
         macro_defs.insert(Mark::root(), root_def_id);
 
@@ -1717,7 +1710,6 @@ impl<'a, 'crateloader: 'a> Resolver<'a, 'crateloader> {
             ambiguity_errors: Vec::new(),
             use_injections: Vec::new(),
             proc_mac_errors: Vec::new(),
-            gated_errors: FxHashSet(),
             disallowed_shadowing: Vec::new(),
             macro_expanded_macro_export_errors: BTreeSet::new(),
 
@@ -1729,15 +1721,11 @@ impl<'a, 'crateloader: 'a> Resolver<'a, 'crateloader> {
                 vis: ty::Visibility::Public,
             }),
 
-            use_extern_macros: features.use_extern_macros(),
-
             crate_loader,
             macro_names: FxHashSet(),
             macro_prelude: FxHashMap(),
             all_macros: FxHashMap(),
-            lexical_macro_resolutions: Vec::new(),
             macro_map: FxHashMap(),
-            macro_exports: Vec::new(),
             invocations,
             macro_defs,
             local_macro_def_scopes: FxHashMap(),
@@ -1770,9 +1758,7 @@ impl<'a, 'crateloader: 'a> Resolver<'a, 'crateloader> {
     fn per_ns<F: FnMut(&mut Self, Namespace)>(&mut self, mut f: F) {
         f(self, TypeNS);
         f(self, ValueNS);
-        if self.use_extern_macros {
-            f(self, MacroNS);
-        }
+        f(self, MacroNS);
     }
 
     fn macro_def(&self, mut ctxt: SyntaxContext) -> DefId {
@@ -2186,11 +2172,8 @@ impl<'a, 'crateloader: 'a> Resolver<'a, 'crateloader> {
 
     fn resolve_item(&mut self, item: &Item) {
         let name = item.ident.name;
-
         debug!("(resolving item) resolving {}", name);
 
-        self.check_proc_macro_attrs(&item.attrs);
-
         match item.node {
             ItemKind::Enum(_, ref generics) |
             ItemKind::Ty(_, ref generics) |
@@ -2218,8 +2201,6 @@ impl<'a, 'crateloader: 'a> Resolver<'a, 'crateloader> {
                         walk_list!(this, visit_param_bound, bounds);
 
                         for trait_item in trait_items {
-                            this.check_proc_macro_attrs(&trait_item.attrs);
-
                             let type_parameters = HasTypeParameters(&trait_item.generics,
                                                                     TraitOrImplItemRibKind);
                             this.with_type_parameter_rib(type_parameters, |this| {
@@ -2498,7 +2479,6 @@ impl<'a, 'crateloader: 'a> Resolver<'a, 'crateloader> {
                         this.visit_generics(generics);
                         this.with_current_self_type(self_type, |this| {
                             for impl_item in impl_items {
-                                this.check_proc_macro_attrs(&impl_item.attrs);
                                 this.resolve_visibility(&impl_item.vis);
 
                                 // We also need a new scope for the impl item type parameters.
@@ -4488,10 +4468,6 @@ impl<'a, 'crateloader: 'a> Resolver<'a, 'crateloader> {
     }
 
     fn report_shadowing_errors(&mut self) {
-        for (ident, scope) in replace(&mut self.lexical_macro_resolutions, Vec::new()) {
-            self.resolve_legacy_scope(scope, ident, true);
-        }
-
         let mut reported_errors = FxHashSet();
         for binding in replace(&mut self.disallowed_shadowing, Vec::new()) {
             if self.resolve_legacy_scope(&binding.parent, binding.ident, false).is_some() &&
@@ -4612,36 +4588,6 @@ impl<'a, 'crateloader: 'a> Resolver<'a, 'crateloader> {
         err.emit();
         self.name_already_seen.insert(name, span);
     }
-
-    fn check_proc_macro_attrs(&mut self, attrs: &[ast::Attribute]) {
-        if self.use_extern_macros { return; }
-
-        for attr in attrs {
-            if attr.path.segments.len() > 1 {
-                continue
-            }
-            let ident = attr.path.segments[0].ident;
-            let result = self.resolve_lexical_macro_path_segment(ident,
-                                                                 MacroNS,
-                                                                 false,
-                                                                 false,
-                                                                 true,
-                                                                 attr.path.span);
-            if let Ok(binding) = result {
-                if let SyntaxExtension::AttrProcMacro(..) = *binding.binding().get_macro(self) {
-                    attr::mark_known(attr);
-
-                    let msg = "attribute procedural macros are experimental";
-                    let feature = "use_extern_macros";
-
-                    feature_err(&self.session.parse_sess, feature,
-                                attr.span, GateIssue::Language, msg)
-                        .span_label(binding.span(), "procedural macro imported here")
-                        .emit();
-                }
-            }
-        }
-    }
 }
 
 fn is_self_type(path: &[Ident], namespace: Namespace) -> bool {

src/librustc_resolve/macros.rs

@@ -16,7 +16,7 @@ use build_reduced_graph::{BuildReducedGraphVisitor, IsMacroExport};
 use resolve_imports::ImportResolver;
 use rustc::hir::def_id::{DefId, BUILTIN_MACROS_CRATE, CRATE_DEF_INDEX, DefIndex,
                          DefIndexAddressSpace};
-use rustc::hir::def::{Def, Export, NonMacroAttrKind};
+use rustc::hir::def::{Def, NonMacroAttrKind};
 use rustc::hir::map::{self, DefCollector};
 use rustc::{ty, lint};
 use rustc::middle::cstore::CrateStore;
@@ -524,21 +524,13 @@ impl<'a, 'cl> Resolver<'a, 'cl> {
         self.current_module = if module.is_trait() { module.parent.unwrap() } else { module };
 
         // Possibly apply the macro helper hack
-        if self.use_extern_macros && kind == MacroKind::Bang && path.len() == 1 &&
+        if kind == MacroKind::Bang && path.len() == 1 &&
            path[0].span.ctxt().outer().expn_info().map_or(false, |info| info.local_inner_macros) {
             let root = Ident::new(keywords::DollarCrate.name(), path[0].span);
             path.insert(0, root);
         }
 
         if path.len() > 1 {
-            if !self.use_extern_macros && self.gated_errors.insert(span) {
-                let msg = "non-ident macro paths are experimental";
-                let feature = "use_extern_macros";
-                emit_feature_err(&self.session.parse_sess, feature, span, GateIssue::Language, msg);
-                self.found_unresolved_macro = true;
-                return Err(Determinacy::Determined);
-            }
-
             let res = self.resolve_path(None, &path, Some(MacroNS), false, span, CrateLint::No);
             let def = match res {
                 PathResult::NonModule(path_res) => match path_res.base_def() {
@@ -843,7 +835,6 @@ impl<'a, 'cl> Resolver<'a, 'cl> {
                                 record_used: bool)
                                 -> Option<MacroBinding<'a>> {
         let ident = ident.modern();
-        let mut possible_time_travel = None;
         let mut relative_depth: u32 = 0;
         let mut binding = None;
         loop {
@@ -853,9 +844,6 @@ impl<'a, 'cl> Resolver<'a, 'cl> {
                     match invocation.expansion.get() {
                         LegacyScope::Invocation(_) => scope.set(invocation.legacy_scope.get()),
                         LegacyScope::Empty => {
-                            if possible_time_travel.is_none() {
-                                possible_time_travel = Some(scope);
-                            }
                             scope = &invocation.legacy_scope;
                         }
                         _ => {
@@ -870,7 +858,7 @@ impl<'a, 'cl> Resolver<'a, 'cl> {
                 }
                 LegacyScope::Binding(potential_binding) => {
                     if potential_binding.ident == ident {
-                        if (!self.use_extern_macros || record_used) && relative_depth > 0 {
+                        if record_used && relative_depth > 0 {
                             self.disallowed_shadowing.push(potential_binding);
                         }
                         binding = Some(potential_binding);
@@ -884,21 +872,11 @@ impl<'a, 'cl> Resolver<'a, 'cl> {
         let binding = if let Some(binding) = binding {
             MacroBinding::Legacy(binding)
         } else if let Some(binding) = self.macro_prelude.get(&ident.name).cloned() {
-            if !self.use_extern_macros {
-                self.record_use(ident, MacroNS, binding, DUMMY_SP);
-            }
             MacroBinding::Global(binding)
         } else {
             return None;
         };
 
-        if !self.use_extern_macros {
-            if let Some(scope) = possible_time_travel {
-                // Check for disallowed shadowing later
-                self.lexical_macro_resolutions.push((ident, scope));
-            }
-        }
-
         Some(binding)
     }
 
@@ -1008,9 +986,6 @@ impl<'a, 'cl> Resolver<'a, 'cl> {
             find_best_match_for_name(names, name, None)
         // Then check modules.
         }).or_else(|| {
-            if !self.use_extern_macros {
-                return None;
-            }
             let is_macro = |def| {
                 if let Def::Macro(_, def_kind) = def {
                     def_kind == kind
@@ -1086,19 +1061,10 @@ impl<'a, 'cl> Resolver<'a, 'cl> {
             let def = Def::Macro(def_id, MacroKind::Bang);
             self.all_macros.insert(ident.name, def);
             if attr::contains_name(&item.attrs, "macro_export") {
-                if self.use_extern_macros {
-                    let module = self.graph_root;
-                    let vis = ty::Visibility::Public;
-                    self.define(module, ident, MacroNS,
-                                (def, vis, item.span, expansion, IsMacroExport));
-                } else {
-                    self.macro_exports.push(Export {
-                        ident: ident.modern(),
-                        def: def,
-                        vis: ty::Visibility::Public,
-                        span: item.span,
-                    });
-                }
+                let module = self.graph_root;
+                let vis = ty::Visibility::Public;
+                self.define(module, ident, MacroNS,
+                            (def, vis, item.span, expansion, IsMacroExport));
             } else {
                 self.unused_macros.insert(def_id);
             }

src/librustc_resolve/resolve_imports.rs

@@ -24,7 +24,7 @@ use rustc::lint::builtin::{DUPLICATE_MACRO_EXPORTS, PUB_USE_OF_PRIVATE_EXTERN_CR
 use rustc::hir::def_id::{CRATE_DEF_INDEX, DefId};
 use rustc::hir::def::*;
 use rustc::session::DiagnosticMessageId;
-use rustc::util::nodemap::{FxHashMap, FxHashSet};
+use rustc::util::nodemap::FxHashSet;
 
 use syntax::ast::{Ident, Name, NodeId, CRATE_NODE_ID};
 use syntax::ext::base::Determinacy::{self, Determined, Undetermined};
@@ -1142,24 +1142,6 @@ impl<'a, 'b:'a, 'c: 'b> ImportResolver<'a, 'b, 'c> {
         *module.globs.borrow_mut() = Vec::new();
 
         let mut reexports = Vec::new();
-        let mut exported_macro_names = FxHashMap();
-        if ptr::eq(module, self.graph_root) {
-            let macro_exports = mem::replace(&mut self.macro_exports, Vec::new());
-            for export in macro_exports.into_iter().rev() {
-                if let Some(later_span) = exported_macro_names.insert(export.ident.modern(),
-                                                                      export.span) {
-                    self.session.buffer_lint_with_diagnostic(
-                        DUPLICATE_MACRO_EXPORTS,
-                        CRATE_NODE_ID,
-                        later_span,
-                        &format!("a macro named `{}` has already been exported", export.ident),
-                        BuiltinLintDiagnostics::DuplicatedMacroExports(
-                            export.ident, export.span, later_span));
-                } else {
-                    reexports.push(export);
-                }
-            }
-        }
 
         for (&(ident, ns), resolution) in module.resolutions.borrow().iter() {
             let resolution = &mut *resolution.borrow_mut();
@@ -1174,16 +1156,6 @@ impl<'a, 'b:'a, 'c: 'b> ImportResolver<'a, 'b, 'c> {
                     if !def.def_id().is_local() {
                         self.cstore.export_macros_untracked(def.def_id().krate);
                     }
-                    if let Def::Macro(..) = def {
-                        if let Some(&span) = exported_macro_names.get(&ident.modern()) {
-                            let msg =
-                                format!("a macro named `{}` has already been exported", ident);
-                            self.session.struct_span_err(span, &msg)
-                                .span_label(span, format!("`{}` already exported", ident))
-                                .span_note(binding.span, "previous macro export here")
-                                .emit();
-                        }
-                    }
                     reexports.push(Export {
                         ident: ident.modern(),
                         def: def,

src/libstd/lib.rs

@@ -302,7 +302,7 @@
 #![feature(unboxed_closures)]
 #![feature(untagged_unions)]
 #![feature(unwind_attributes)]
-#![feature(use_extern_macros)]
+#![cfg_attr(stage0, feature(use_extern_macros))]
 #![feature(doc_cfg)]
 #![feature(doc_masked)]
 #![feature(doc_spotlight)]

src/libsyntax/ext/expand.rs

@@ -1124,9 +1124,7 @@ impl<'a, 'b> InvocationCollector<'a, 'b> {
                 return attrs;
             }
 
-            if self.cx.ecfg.use_extern_macros_enabled() {
-                attr = find_attr_invoc(&mut attrs);
-            }
+            attr = find_attr_invoc(&mut attrs);
             traits = collect_derives(&mut self.cx, &mut attrs);
             attrs
         });
@@ -1147,9 +1145,7 @@ impl<'a, 'b> InvocationCollector<'a, 'b> {
                 return attrs;
             }
 
-            if self.cx.ecfg.use_extern_macros_enabled() {
-                attr = find_attr_invoc(&mut attrs);
-            }
+            attr = find_attr_invoc(&mut attrs);
             attrs
         });
 
@@ -1667,10 +1663,6 @@ impl<'feat> ExpansionConfig<'feat> {
         fn proc_macro_expr = proc_macro_expr,
         fn proc_macro_non_items = proc_macro_non_items,
     }
-
-    pub fn use_extern_macros_enabled(&self) -> bool {
-        self.features.map_or(false, |features| features.use_extern_macros())
-    }
 }
 
 // A Marker adds the given mark to the syntax context.