Auto merge of #40220 - jseyfried:ast_macro_def, r=nrc

syntax: add `ast::ItemKind::MacroDef`, simplify hygiene info

This PR
 - adds a new variant `MacroDef` to `ast::ItemKind` for `macro_rules!` and eventually `macro` items,
 - [breaking-change] forbids macro defs without a name (`macro_rules! { () => {} }` compiles today),
 - removes `ast::MacroDef`, and
 - no longer uses `Mark` and `Invocation` to identify and characterize macro definitions.
   - We used to apply (at least) two `Mark`s to an expanded identifier's `SyntaxContext` -- the definition mark(s) and the expansion mark(s). We now only apply the latter.

r? @nrc

src/librustc/hir/lowering.rs

@@ -79,6 +79,7 @@ pub struct LoweringContext<'a> {
     trait_items: BTreeMap<hir::TraitItemId, hir::TraitItem>,
     impl_items: BTreeMap<hir::ImplItemId, hir::ImplItem>,
     bodies: BTreeMap<hir::BodyId, hir::Body>,
+    exported_macros: Vec<hir::MacroDef>,
 
     trait_impls: BTreeMap<DefId, Vec<NodeId>>,
     trait_default_impl: BTreeMap<DefId, NodeId>,
@@ -121,6 +122,7 @@ pub fn lower_crate(sess: &Session,
         bodies: BTreeMap::new(),
         trait_impls: BTreeMap::new(),
         trait_default_impl: BTreeMap::new(),
+        exported_macros: Vec::new(),
         loop_scopes: Vec::new(),
         is_in_loop_condition: false,
         type_def_lifetime_params: DefIdMap(),
@@ -170,9 +172,10 @@ impl<'a> LoweringContext<'a> {
 
         impl<'lcx, 'interner> Visitor<'lcx> for ItemLowerer<'lcx, 'interner> {
             fn visit_item(&mut self, item: &'lcx Item) {
-                let hir_item = self.lctx.lower_item(item);
-                self.lctx.items.insert(item.id, hir_item);
-                visit::walk_item(self, item);
+                if let Some(hir_item) = self.lctx.lower_item(item) {
+                    self.lctx.items.insert(item.id, hir_item);
+                    visit::walk_item(self, item);
+                }
             }
 
             fn visit_trait_item(&mut self, item: &'lcx TraitItem) {
@@ -195,14 +198,13 @@ impl<'a> LoweringContext<'a> {
 
         let module = self.lower_mod(&c.module);
         let attrs = self.lower_attrs(&c.attrs);
-        let exported_macros = c.exported_macros.iter().map(|m| self.lower_macro_def(m)).collect();
         let body_ids = body_ids(&self.bodies);
 
         hir::Crate {
             module: module,
             attrs: attrs,
             span: c.span,
-            exported_macros: exported_macros,
+            exported_macros: hir::HirVec::from(self.exported_macros),
             items: self.items,
             trait_items: self.trait_items,
             impl_items: self.impl_items,
@@ -1134,7 +1136,7 @@ impl<'a> LoweringContext<'a> {
                                bounds,
                                items)
             }
-            ItemKind::Mac(_) => panic!("Shouldn't still be around"),
+            ItemKind::MacroDef(..) | ItemKind::Mac(..) => panic!("Shouldn't still be around"),
         }
     }
 
@@ -1256,42 +1258,45 @@ impl<'a> LoweringContext<'a> {
         }
     }
 
-    fn lower_macro_def(&mut self, m: &MacroDef) -> hir::MacroDef {
-        hir::MacroDef {
-            name: m.ident.name,
-            attrs: self.lower_attrs(&m.attrs),
-            id: m.id,
-            span: m.span,
-            body: m.body.clone().into(),
-        }
-    }
-
     fn lower_item_id(&mut self, i: &Item) -> SmallVector<hir::ItemId> {
-        if let ItemKind::Use(ref view_path) = i.node {
-            if let ViewPathList(_, ref imports) = view_path.node {
-                return iter::once(i.id).chain(imports.iter().map(|import| import.node.id))
-                    .map(|id| hir::ItemId { id: id }).collect();
+        match i.node {
+            ItemKind::Use(ref view_path) => {
+                if let ViewPathList(_, ref imports) = view_path.node {
+                    return iter::once(i.id).chain(imports.iter().map(|import| import.node.id))
+                        .map(|id| hir::ItemId { id: id }).collect();
+                }
             }
+            ItemKind::MacroDef(..) => return SmallVector::new(),
+            _ => {}
         }
         SmallVector::one(hir::ItemId { id: i.id })
     }
 
-    pub fn lower_item(&mut self, i: &Item) -> hir::Item {
+    pub fn lower_item(&mut self, i: &Item) -> Option<hir::Item> {
         let mut name = i.ident.name;
         let attrs = self.lower_attrs(&i.attrs);
         let mut vis = self.lower_visibility(&i.vis);
+        if let ItemKind::MacroDef(ref tts) = i.node {
+            if i.attrs.iter().any(|attr| attr.name() == "macro_export") {
+                self.exported_macros.push(hir::MacroDef {
+                    name: name, attrs: attrs, id: i.id, span: i.span, body: tts.clone().into(),
+                });
+            }
+            return None;
+        }
+
         let node = self.with_parent_def(i.id, |this| {
             this.lower_item_kind(i.id, &mut name, &attrs, &mut vis, &i.node)
         });
 
-        hir::Item {
+        Some(hir::Item {
             id: i.id,
             name: name,
             attrs: attrs,
             node: node,
             vis: vis,
             span: i.span,
-        }
+        })
     }
 
     fn lower_foreign_item(&mut self, i: &ForeignItem) -> hir::ForeignItem {

src/librustc/hir/map/def_collector.rs

@@ -108,7 +108,7 @@ impl<'a> visit::Visitor<'a> for DefCollector<'a> {
             ItemKind::Mod(..) => DefPathData::Module(i.ident.name.as_str()),
             ItemKind::Static(..) | ItemKind::Const(..) | ItemKind::Fn(..) =>
                 DefPathData::ValueNs(i.ident.name.as_str()),
-            ItemKind::Mac(..) if i.id == DUMMY_NODE_ID => return, // Scope placeholder
+            ItemKind::MacroDef(..) => DefPathData::MacroDef(i.ident.name.as_str()),
             ItemKind::Mac(..) => return self.visit_macro_invoc(i.id, false),
             ItemKind::Use(ref view_path) => {
                 match view_path.node {
@@ -269,10 +269,6 @@ impl<'a> visit::Visitor<'a> for DefCollector<'a> {
         self.create_def(def.lifetime.id, DefPathData::LifetimeDef(def.lifetime.name.as_str()));
     }
 
-    fn visit_macro_def(&mut self, macro_def: &'a MacroDef) {
-        self.create_def(macro_def.id, DefPathData::MacroDef(macro_def.ident.name.as_str()));
-    }
-
     fn visit_stmt(&mut self, stmt: &'a Stmt) {
         match stmt.node {
             StmtKind::Mac(..) => self.visit_macro_invoc(stmt.id, false),

src/librustc/middle/cstore.rs

@@ -136,7 +136,7 @@ pub struct NativeLibrary {
 }
 
 pub enum LoadedMacro {
-    MacroRules(ast::MacroDef),
+    MacroDef(ast::Item),
     ProcMacro(Rc<SyntaxExtension>),
 }
 

src/librustc_driver/driver.rs

@@ -43,7 +43,6 @@ use super::Compilation;
 use serialize::json;
 
 use std::env;
-use std::mem;
 use std::ffi::{OsString, OsStr};
 use std::fs;
 use std::io::{self, Write};
@@ -708,8 +707,6 @@ pub fn phase_2_configure_and_expand<F>(sess: &Session,
         krate
     });
 
-    krate.exported_macros = mem::replace(&mut resolver.exported_macros, Vec::new());
-
     krate = time(time_passes, "maybe building test harness", || {
         syntax::test::modify_for_testing(&sess.parse_sess,
                                          &mut resolver,

src/librustc_metadata/cstore_impl.rs

@@ -414,12 +414,13 @@ impl CrateStore for cstore::CStore {
         sess.imported_macro_spans.borrow_mut()
             .insert(local_span, (name.to_string(), data.get_span(id.index, sess)));
 
-        LoadedMacro::MacroRules(ast::MacroDef {
+        LoadedMacro::MacroDef(ast::Item {
             ident: ast::Ident::with_empty_ctxt(name),
             id: ast::DUMMY_NODE_ID,
             span: local_span,
             attrs: attrs,
-            body: body.into(),
+            node: ast::ItemKind::MacroDef(body.into()),
+            vis: ast::Visibility::Inherited,
         })
     }
 

src/librustc_passes/hir_stats.rs

@@ -375,9 +375,4 @@ impl<'v> ast_visit::Visitor<'v> for StatCollector<'v> {
     fn visit_attribute(&mut self, attr: &'v ast::Attribute) {
         self.record("Attribute", Id::None, attr);
     }
-
-    fn visit_macro_def(&mut self, macro_def: &'v ast::MacroDef) {
-        self.record("MacroDef", Id::None, macro_def);
-        ast_visit::walk_macro_def(self, macro_def)
-    }
 }

src/librustc_resolve/build_reduced_graph.rs

@@ -37,7 +37,6 @@ use syntax::ast::{Mutability, StmtKind, TraitItem, TraitItemKind};
 use syntax::ast::{Variant, ViewPathGlob, ViewPathList, ViewPathSimple};
 use syntax::ext::base::SyntaxExtension;
 use syntax::ext::base::Determinacy::Undetermined;
-use syntax::ext::expand::mark_tts;
 use syntax::ext::hygiene::Mark;
 use syntax::ext::tt::macro_rules;
 use syntax::parse::token;
@@ -373,7 +372,7 @@ impl<'a> Resolver<'a> {
                 self.define(parent, ident, TypeNS, (module, vis, sp, expansion));
                 self.current_module = module;
             }
-            ItemKind::Mac(_) => panic!("unexpanded macro in resolve!"),
+            ItemKind::MacroDef(..) | ItemKind::Mac(_) => unreachable!(),
         }
     }
 
@@ -493,6 +492,16 @@ impl<'a> Resolver<'a> {
         })
     }
 
+    pub fn macro_def_scope(&mut self, expansion: Mark) -> Module<'a> {
+        let def_id = self.macro_defs[&expansion];
+        if let Some(id) = self.definitions.as_local_node_id(def_id) {
+            self.local_macro_def_scopes[&id]
+        } else {
+            let module_def_id = ty::DefIdTree::parent(&*self, def_id).unwrap();
+            self.get_extern_crate_root(module_def_id.krate)
+        }
+    }
+
     pub fn get_macro(&mut self, def: Def) -> Rc<SyntaxExtension> {
         let def_id = match def {
             Def::Macro(def_id, ..) => def_id,
@@ -502,22 +511,12 @@ impl<'a> Resolver<'a> {
             return ext.clone();
         }
 
-        let mut macro_rules = match self.session.cstore.load_macro(def_id, &self.session) {
-            LoadedMacro::MacroRules(macro_rules) => macro_rules,
+        let macro_def = match self.session.cstore.load_macro(def_id, &self.session) {
+            LoadedMacro::MacroDef(macro_def) => macro_def,
             LoadedMacro::ProcMacro(ext) => return ext,
         };
 
-        let mark = Mark::fresh();
-        let invocation = self.arenas.alloc_invocation_data(InvocationData {
-            module: Cell::new(self.get_extern_crate_root(def_id.krate)),
-            def_index: CRATE_DEF_INDEX,
-            const_expr: false,
-            legacy_scope: Cell::new(LegacyScope::Empty),
-            expansion: Cell::new(LegacyScope::Empty),
-        });
-        self.invocations.insert(mark, invocation);
-        macro_rules.body = mark_tts(macro_rules.stream(), mark).into();
-        let ext = Rc::new(macro_rules::compile(&self.session.parse_sess, &macro_rules));
+        let ext = Rc::new(macro_rules::compile(&self.session.parse_sess, &macro_def));
         self.macro_map.insert(def_id, ext.clone());
         ext
     }
@@ -707,12 +706,12 @@ impl<'a, 'b> Visitor<'a> for BuildReducedGraphVisitor<'a, 'b> {
 
     fn visit_item(&mut self, item: &'a Item) {
         let macro_use = match item.node {
-            ItemKind::Mac(ref mac) => {
-                if mac.node.path.segments.is_empty() {
-                    self.legacy_scope = LegacyScope::Expansion(self.visit_invoc(item.id));
-                } else {
-                    self.resolver.define_macro(item, &mut self.legacy_scope);
-                }
+            ItemKind::MacroDef(..) => {
+                self.resolver.define_macro(item, &mut self.legacy_scope);
+                return
+            }
+            ItemKind::Mac(..) => {
+                self.legacy_scope = LegacyScope::Expansion(self.visit_invoc(item.id));
                 return
             }
             ItemKind::Mod(..) => self.resolver.contains_macro_use(&item.attrs),