resolve/metadata: Stop encoding macros as reexports

compiler/rustc_ast_lowering/src/item.rs

@@ -444,8 +444,8 @@ impl<'hir> LoweringContext<'_, 'hir> {
             ),
             ItemKind::MacroDef(MacroDef { ref body, macro_rules }) => {
                 let body = P(self.lower_mac_args(body));
-
-                hir::ItemKind::Macro(ast::MacroDef { body, macro_rules })
+                let macro_kind = self.resolver.decl_macro_kind(self.resolver.local_def_id(id));
+                hir::ItemKind::Macro(ast::MacroDef { body, macro_rules }, macro_kind)
             }
             ItemKind::MacCall(..) => {
                 panic!("`TyMac` should have been expanded by now")

compiler/rustc_ast_lowering/src/lib.rs

@@ -61,7 +61,7 @@ use rustc_session::lint::LintBuffer;
 use rustc_session::parse::feature_err;
 use rustc_session::utils::{FlattenNonterminals, NtToTokenstream};
 use rustc_session::Session;
-use rustc_span::hygiene::ExpnId;
+use rustc_span::hygiene::{ExpnId, MacroKind};
 use rustc_span::source_map::{respan, DesugaringKind};
 use rustc_span::symbol::{kw, sym, Ident, Symbol};
 use rustc_span::{Span, DUMMY_SP};
@@ -210,6 +210,8 @@ pub trait ResolverAstLowering {
         expn_id: ExpnId,
         span: Span,
     ) -> LocalDefId;
+
+    fn decl_macro_kind(&self, def_id: LocalDefId) -> MacroKind;
 }
 
 /// Context of `impl Trait` in code, which determines whether it is allowed in an HIR subtree,

compiler/rustc_hir/src/hir.rs

@@ -15,6 +15,7 @@ use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::sorted_map::SortedMap;
 use rustc_index::vec::IndexVec;
 use rustc_macros::HashStable_Generic;
+use rustc_span::hygiene::MacroKind;
 use rustc_span::source_map::Spanned;
 use rustc_span::symbol::{kw, sym, Ident, Symbol};
 use rustc_span::{def_id::LocalDefId, BytePos, MultiSpan, Span, DUMMY_SP};
@@ -2803,7 +2804,7 @@ pub enum ItemKind<'hir> {
     /// A function declaration.
     Fn(FnSig<'hir>, Generics<'hir>, BodyId),
     /// A MBE macro definition (`macro_rules!` or `macro`).
-    Macro(ast::MacroDef),
+    Macro(ast::MacroDef, MacroKind),
     /// A module.
     Mod(Mod<'hir>),
     /// An external module, e.g. `extern { .. }`.

compiler/rustc_hir/src/intravisit.rs

@@ -575,7 +575,7 @@ pub fn walk_item<'v, V: Visitor<'v>>(visitor: &mut V, item: &'v Item<'v>) {
             item.span,
             item.hir_id(),
         ),
-        ItemKind::Macro(_) => {
+        ItemKind::Macro(..) => {
             visitor.visit_id(item.hir_id());
         }
         ItemKind::Mod(ref module) => {

compiler/rustc_hir_pretty/src/lib.rs

@@ -570,7 +570,7 @@ impl<'a> State<'a> {
                 self.end(); // need to close a box
                 self.ann.nested(self, Nested::Body(body));
             }
-            hir::ItemKind::Macro(ref macro_def) => {
+            hir::ItemKind::Macro(ref macro_def, _) => {
                 self.print_mac_def(macro_def, &item.ident, item.span, |state| {
                     state.print_visibility(&item.vis)
                 });

compiler/rustc_metadata/src/rmeta/decoder.rs

@@ -5,6 +5,7 @@ use crate::rmeta::table::{FixedSizeEncoding, Table};
 use crate::rmeta::*;
 
 use rustc_ast as ast;
+use rustc_ast::ptr::P;
 use rustc_attr as attr;
 use rustc_data_structures::captures::Captures;
 use rustc_data_structures::fx::FxHashMap;
@@ -1076,6 +1077,7 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
                         res,
                         vis: ty::Visibility::Public,
                         span: ident.span,
+                        macro_rules: false,
                     });
                 }
             }
@@ -1087,17 +1089,19 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
             for child_index in children.decode((self, sess)) {
                 if let Some(ident) = self.opt_item_ident(child_index, sess) {
                     let kind = self.def_kind(child_index);
-                    if matches!(kind, DefKind::Macro(..)) {
-                        // FIXME: Macros are currently encoded twice, once as items and once as
-                        // reexports. We ignore the items here and only use the reexports.
-                        continue;
-                    }
                     let def_id = self.local_def_id(child_index);
                     let res = Res::Def(kind, def_id);
                     let vis = self.get_visibility(child_index);
                     let span = self.get_span(child_index, sess);
+                    let macro_rules = match kind {
+                        DefKind::Macro(..) => match self.kind(child_index) {
+                            EntryKind::MacroDef(_, macro_rules) => macro_rules,
+                            _ => unreachable!(),
+                        },
+                        _ => false,
+                    };
 
-                    callback(ModChild { ident, res, vis, span });
+                    callback(ModChild { ident, res, vis, span, macro_rules });
 
                     // For non-re-export structs and variants add their constructors to children.
                     // Re-export lists automatically contain constructors when necessary.
@@ -1109,7 +1113,13 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
                                 let ctor_res =
                                     Res::Def(DefKind::Ctor(CtorOf::Struct, ctor_kind), ctor_def_id);
                                 let vis = self.get_visibility(ctor_def_id.index);
-                                callback(ModChild { ident, res: ctor_res, vis, span });
+                                callback(ModChild {
+                                    ident,
+                                    res: ctor_res,
+                                    vis,
+                                    span,
+                                    macro_rules: false,
+                                });
                             }
                         }
                         DefKind::Variant => {
@@ -1134,7 +1144,13 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
                                     vis = ty::Visibility::Restricted(crate_def_id);
                                 }
                             }
-                            callback(ModChild { ident, res: ctor_res, vis, span });
+                            callback(ModChild {
+                                ident,
+                                res: ctor_res,
+                                vis,
+                                span,
+                                macro_rules: false,
+                            });
                         }
                         _ => {}
                     }
@@ -1402,9 +1418,11 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
         tcx.arena.alloc_from_iter(self.root.exported_symbols.decode((self, tcx)))
     }
 
-    fn get_macro(self, id: DefIndex, sess: &Session) -> MacroDef {
+    fn get_macro(self, id: DefIndex, sess: &Session) -> ast::MacroDef {
         match self.kind(id) {
-            EntryKind::MacroDef(macro_def) => macro_def.decode((self, sess)),
+            EntryKind::MacroDef(mac_args, macro_rules) => {
+                ast::MacroDef { body: P(mac_args.decode((self, sess))), macro_rules }
+            }
             _ => bug!(),
         }
     }

compiler/rustc_metadata/src/rmeta/encoder.rs

@@ -1406,8 +1406,8 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
 
                 EntryKind::Fn(self.lazy(data))
             }
-            hir::ItemKind::Macro(ref macro_def) => {
-                EntryKind::MacroDef(self.lazy(macro_def.clone()))
+            hir::ItemKind::Macro(ref macro_def, _) => {
+                EntryKind::MacroDef(self.lazy(&*macro_def.body), macro_def.macro_rules)
             }
             hir::ItemKind::Mod(ref m) => {
                 return self.encode_info_for_mod(item.def_id, m);

compiler/rustc_metadata/src/rmeta/mod.rs

@@ -2,7 +2,7 @@ use decoder::Metadata;
 use def_path_hash_map::DefPathHashMapRef;
 use table::{Table, TableBuilder};
 
-use rustc_ast::{self as ast, MacroDef};
+use rustc_ast as ast;
 use rustc_attr as attr;
 use rustc_data_structures::svh::Svh;
 use rustc_data_structures::sync::MetadataRef;
@@ -350,7 +350,7 @@ enum EntryKind {
     Fn(Lazy<FnData>),
     ForeignFn(Lazy<FnData>),
     Mod(Lazy<[ModChild]>),
-    MacroDef(Lazy<MacroDef>),
+    MacroDef(Lazy<ast::MacArgs>, /*macro_rules*/ bool),
     ProcMacro(MacroKind),
     Closure,
     Generator,

compiler/rustc_middle/src/hir/map/mod.rs

@@ -14,7 +14,6 @@ use rustc_hir::*;
 use rustc_index::vec::Idx;
 use rustc_middle::hir::nested_filter;
 use rustc_span::def_id::StableCrateId;
-use rustc_span::hygiene::MacroKind;
 use rustc_span::source_map::Spanned;
 use rustc_span::symbol::{kw, sym, Ident, Symbol};
 use rustc_span::Span;
@@ -232,7 +231,7 @@ impl<'hir> Map<'hir> {
                 ItemKind::Static(..) => DefKind::Static,
                 ItemKind::Const(..) => DefKind::Const,
                 ItemKind::Fn(..) => DefKind::Fn,
-                ItemKind::Macro(..) => DefKind::Macro(MacroKind::Bang),
+                ItemKind::Macro(_, macro_kind) => DefKind::Macro(macro_kind),
                 ItemKind::Mod(..) => DefKind::Mod,
                 ItemKind::OpaqueTy(..) => DefKind::OpaqueTy,
                 ItemKind::TyAlias(..) => DefKind::TyAlias,

compiler/rustc_middle/src/metadata.rs

@@ -21,4 +21,6 @@ pub struct ModChild {
     pub vis: ty::Visibility,
     /// Span of the item.
     pub span: Span,
+    /// A proper `macro_rules` item (not a reexport).
+    pub macro_rules: bool,
 }

compiler/rustc_passes/src/check_attr.rs

@@ -1951,7 +1951,7 @@ impl<'tcx> Visitor<'tcx> for CheckAttrVisitor<'tcx> {
         // Historically we've run more checks on non-exported than exported macros,
         // so this lets us continue to run them while maintaining backwards compatibility.
         // In the long run, the checks should be harmonized.
-        if let ItemKind::Macro(ref macro_def) = item.kind {
+        if let ItemKind::Macro(ref macro_def, _) = item.kind {
             let def_id = item.def_id.to_def_id();
             if macro_def.macro_rules && !self.tcx.has_attr(def_id, sym::macro_export) {
                 check_non_exported_macro_for_invalid_attrs(self.tcx, item);

compiler/rustc_privacy/src/lib.rs

@@ -564,7 +564,7 @@ impl<'tcx> EmbargoVisitor<'tcx> {
             // privacy and mark them reachable.
             DefKind::Macro(_) => {
                 let item = self.tcx.hir().expect_item(def_id);
-                if let hir::ItemKind::Macro(MacroDef { macro_rules: false, .. }) = item.kind {
+                if let hir::ItemKind::Macro(MacroDef { macro_rules: false, .. }, _) = item.kind {
                     if vis.is_accessible_from(module.to_def_id(), self.tcx) {
                         self.update(def_id, level);
                     }
@@ -686,7 +686,7 @@ impl<'tcx> Visitor<'tcx> for EmbargoVisitor<'tcx> {
                     }
                 }
             }
-            hir::ItemKind::Macro(ref macro_def) => {
+            hir::ItemKind::Macro(ref macro_def, _) => {
                 self.update_reachability_from_macro(item.def_id, macro_def);
             }
             hir::ItemKind::ForeignMod { items, .. } => {

compiler/rustc_resolve/src/access_levels.rs

@@ -133,7 +133,7 @@ impl<'r, 'ast> Visitor<'ast> for AccessLevelsVisitor<'ast, 'r> {
             ast::ItemKind::Impl(..) => return,
 
             // Only exported `macro_rules!` items are public, but they always are
-            ast::ItemKind::MacroDef(..) => {
+            ast::ItemKind::MacroDef(ref macro_def) if macro_def.macro_rules => {
                 let is_macro_export =
                     item.attrs.iter().any(|attr| attr.has_name(sym::macro_export));
                 if is_macro_export { Some(AccessLevel::Public) } else { None }
@@ -155,7 +155,8 @@ impl<'r, 'ast> Visitor<'ast> for AccessLevelsVisitor<'ast, 'r> {
             | ast::ItemKind::Struct(..)
             | ast::ItemKind::Union(..)
             | ast::ItemKind::Trait(..)
-            | ast::ItemKind::TraitAlias(..) => {
+            | ast::ItemKind::TraitAlias(..)
+            | ast::ItemKind::MacroDef(..) => {
                 if item.vis.kind.is_pub() {
                     self.prev_level
                 } else {

compiler/rustc_resolve/src/build_reduced_graph.rs

@@ -940,7 +940,7 @@ impl<'a, 'b> BuildReducedGraphVisitor<'a, 'b> {
     /// Builds the reduced graph for a single item in an external crate.
     fn build_reduced_graph_for_external_crate_res(&mut self, child: ModChild) {
         let parent = self.parent_scope.module;
-        let ModChild { ident, res, vis, span } = child;
+        let ModChild { ident, res, vis, span, macro_rules } = child;
         let res = res.expect_non_local();
         let expansion = self.parent_scope.expansion;
         // Record primary definitions.
@@ -972,7 +972,9 @@ impl<'a, 'b> BuildReducedGraphVisitor<'a, 'b> {
                 _,
             ) => self.r.define(parent, ident, ValueNS, (res, vis, span, expansion)),
             Res::Def(DefKind::Macro(..), _) | Res::NonMacroAttr(..) => {
-                self.r.define(parent, ident, MacroNS, (res, vis, span, expansion))
+                if !macro_rules {
+                    self.r.define(parent, ident, MacroNS, (res, vis, span, expansion))
+                }
             }
             Res::Def(
                 DefKind::TyParam

compiler/rustc_resolve/src/imports.rs

@@ -1399,14 +1399,22 @@ impl<'a, 'b> ImportResolver<'a, 'b> {
         let mut reexports = Vec::new();
 
         module.for_each_child(self.r, |_, ident, _, binding| {
-            // Filter away ambiguous imports and anything that has def-site hygiene.
-            // FIXME: Implement actual cross-crate hygiene.
-            let is_good_import =
-                binding.is_import() && !binding.is_ambiguity() && !ident.span.from_expansion();
-            if is_good_import || binding.is_macro_def() {
+            // FIXME: Consider changing the binding inserted by `#[macro_export] macro_rules`
+            // into the crate root to actual `NameBindingKind::Import`.
+            if binding.is_import()
+                || matches!(binding.kind, NameBindingKind::Res(_, _is_macro_export @ true))
+            {
                 let res = binding.res().expect_non_local();
-                if res != def::Res::Err {
-                    reexports.push(ModChild { ident, res, vis: binding.vis, span: binding.span });
+                // Ambiguous imports are treated as errors at this point and are
+                // not exposed to other crates (see #36837 for more details).
+                if res != def::Res::Err && !binding.is_ambiguity() {
+                    reexports.push(ModChild {
+                        ident,
+                        res,
+                        vis: binding.vis,
+                        span: binding.span,
+                        macro_rules: false,
+                    });
                 }
             }
         });

compiler/rustc_resolve/src/lib.rs

@@ -845,10 +845,6 @@ impl<'a> NameBinding<'a> {
         )
     }
 
-    fn is_macro_def(&self) -> bool {
-        matches!(self.kind, NameBindingKind::Res(Res::Def(DefKind::Macro(..), _), _))
-    }
-
     fn macro_kind(&self) -> Option<MacroKind> {
         self.res().macro_kind()
     }
@@ -990,6 +986,9 @@ pub struct Resolver<'a> {
     crate_loader: CrateLoader<'a>,
     macro_names: FxHashSet<Ident>,
     builtin_macros: FxHashMap<Symbol, BuiltinMacroState>,
+    /// A small map keeping true kinds of built-in macros that appear to be fn-like on
+    /// the surface (`macro` items in libcore), but are actually attributes or derives.
+    builtin_macro_kinds: FxHashMap<LocalDefId, MacroKind>,
     registered_attrs: FxHashSet<Ident>,
     registered_tools: RegisteredTools,
     macro_use_prelude: FxHashMap<Symbol, &'a NameBinding<'a>>,
@@ -1261,6 +1260,10 @@ impl ResolverAstLowering for Resolver<'_> {
 
         def_id
     }
+
+    fn decl_macro_kind(&self, def_id: LocalDefId) -> MacroKind {
+        self.builtin_macro_kinds.get(&def_id).copied().unwrap_or(MacroKind::Bang)
+    }
 }
 
 impl<'a> Resolver<'a> {
@@ -1381,6 +1384,7 @@ impl<'a> Resolver<'a> {
             crate_loader: CrateLoader::new(session, metadata_loader, crate_name),
             macro_names: FxHashSet::default(),
             builtin_macros: Default::default(),
+            builtin_macro_kinds: Default::default(),
             registered_attrs,
             registered_tools,
             macro_use_prelude: FxHashMap::default(),

compiler/rustc_resolve/src/macros.rs

@@ -1209,7 +1209,13 @@ impl<'a> Resolver<'a> {
                 // while still taking everything else from the source code.
                 // If we already loaded this builtin macro, give a better error message than 'no such builtin macro'.
                 match mem::replace(builtin_macro, BuiltinMacroState::AlreadySeen(item.span)) {
-                    BuiltinMacroState::NotYetSeen(ext) => result.kind = ext,
+                    BuiltinMacroState::NotYetSeen(ext) => {
+                        result.kind = ext;
+                        if item.id != ast::DUMMY_NODE_ID {
+                            self.builtin_macro_kinds
+                                .insert(self.local_def_id(item.id), result.macro_kind());
+                        }
+                    }
                     BuiltinMacroState::AlreadySeen(span) => {
                         struct_span_err!(
                             self.session,

compiler/rustc_save_analysis/src/sig.rs

@@ -416,7 +416,7 @@ impl<'hir> Sig for hir::Item<'hir> {
 
                 Ok(sig)
             }
-            hir::ItemKind::Macro(_) => {
+            hir::ItemKind::Macro(..) => {
                 let mut text = "macro".to_owned();
                 let name = self.ident.to_string();
                 text.push_str(&name);

compiler/rustc_typeck/src/collect.rs

@@ -730,7 +730,7 @@ fn convert_item(tcx: TyCtxt<'_>, item_id: hir::ItemId) {
         // These don't define types.
         hir::ItemKind::ExternCrate(_)
         | hir::ItemKind::Use(..)
-        | hir::ItemKind::Macro(_)
+        | hir::ItemKind::Macro(..)
         | hir::ItemKind::Mod(_)
         | hir::ItemKind::GlobalAsm(_) => {}
         hir::ItemKind::ForeignMod { items, .. } => {

src/librustdoc/clean/mod.rs

@@ -1855,7 +1855,7 @@ fn clean_maybe_renamed_item(
             ItemKind::Fn(ref sig, ref generics, body_id) => {
                 clean_fn_or_proc_macro(item, sig, generics, body_id, &mut name, cx)
             }
-            ItemKind::Macro(ref macro_def) => {
+            ItemKind::Macro(ref macro_def, _) => {
                 let ty_vis = cx.tcx.visibility(def_id).clean(cx);
                 MacroItem(Macro {
                     source: display_macro_source(cx, name, macro_def, def_id, ty_vis),

src/librustdoc/doctest.rs

@@ -1164,7 +1164,7 @@ impl<'a, 'hir, 'tcx> intravisit::Visitor<'hir> for HirCollector<'a, 'hir, 'tcx>
 
     fn visit_item(&mut self, item: &'hir hir::Item<'_>) {
         let name = match &item.kind {
-            hir::ItemKind::Macro(ref macro_def) => {
+            hir::ItemKind::Macro(ref macro_def, _) => {
                 // FIXME(#88038): Non exported macros have historically not been tested,
                 // but we really ought to start testing them.
                 let def_id = item.def_id.to_def_id();

src/librustdoc/visit_ast.rs

@@ -325,7 +325,7 @@ impl<'a, 'tcx> RustdocVisitor<'a, 'tcx> {
 
                 om.items.push((item, renamed))
             }
-            hir::ItemKind::Macro(ref macro_def) => {
+            hir::ItemKind::Macro(ref macro_def, _) => {
                 // `#[macro_export] macro_rules!` items are handled seperately in `visit()`,
                 // above, since they need to be documented at the module top level. Accordingly,
                 // we only want to handle macros if one of three conditions holds: