Merge #6893

6893: Move to upstream `macro_rules!` model r=matklad a=jonas-schievink

This changes `macro_rules!` from being treated as a macro invocation to being a first-class item. It also disallows using an additional ident argument for regular macros, so `m! ident(...);` now fails to parse.

This matches upstream Rust, and makes the code somewhat simpler by removing repeated "is this a `macro_rules!` call" checks. It will also simplify allowing visibilities on macros, which is currently being proposed in rust-lang/rust#78166.

Co-authored-by: Jonas Schievink <[email protected]>

Author: bors[bot]

Cargo.lock

@@ -25,3 +25,5 @@ debug = 0 # Set this to 1 or 2 to get more useful backtraces in debugger.
 # chalk-solve = { path = "../chalk/chalk-solve" }
 # chalk-ir = { path = "../chalk/chalk-ir" }
 # chalk-recursive = { path = "../chalk/chalk-recursive" }
+
+# ungrammar = { path = "../ungrammar" }

Cargo.toml

@@ -144,7 +144,7 @@ mod tests {
 use foo::<|>;
 //- /foo/lib.rs crate:foo
 #[macro_export]
-macro_rules frobnicate { () => () }
+macro_rules! frobnicate { () => () }
 "#,
             r#"
 use foo::frobnicate;
@@ -154,11 +154,11 @@ use foo::frobnicate;
         check_edit(
             "frobnicate!",
             r#"
-macro_rules frobnicate { () => () }
+macro_rules! frobnicate { () => () }
 fn main() { frob<|>!(); }
 "#,
             r#"
-macro_rules frobnicate { () => () }
+macro_rules! frobnicate { () => () }
 fn main() { frobnicate!(); }
 "#,
         );

crates/completion/src/render/macro_.rs

@@ -110,8 +110,8 @@ impl HasSource for TypeAlias {
     }
 }
 impl HasSource for MacroDef {
-    type Ast = ast::MacroCall;
-    fn source(self, db: &dyn HirDatabase) -> InFile<ast::MacroCall> {
+    type Ast = ast::MacroRules;
+    fn source(self, db: &dyn HirDatabase) -> InFile<ast::MacroRules> {
         InFile {
             file_id: self.id.ast_id.expect("MacroDef without ast_id").file_id,
             value: self.id.ast_id.expect("MacroDef without ast_id").to_node(db.upcast()),

crates/hir/src/has_source.rs

@@ -723,7 +723,7 @@ to_def_impls![
     (crate::EnumVariant, ast::Variant, enum_variant_to_def),
     (crate::TypeParam, ast::TypeParam, type_param_to_def),
     (crate::LifetimeParam, ast::LifetimeParam, lifetime_param_to_def),
-    (crate::MacroDef, ast::MacroCall, macro_call_to_def), // this one is dubious, not all calls are macros
+    (crate::MacroDef, ast::MacroRules, macro_rules_to_def),
     (crate::Local, ast::IdentPat, bind_pat_to_def),
 ];
 

crates/hir/src/semantics.rs

@@ -149,7 +149,10 @@ impl SourceToDefCtx<'_, '_> {
     }
 
     // FIXME: use DynMap as well?
-    pub(super) fn macro_call_to_def(&mut self, src: InFile<ast::MacroCall>) -> Option<MacroDefId> {
+    pub(super) fn macro_rules_to_def(
+        &mut self,
+        src: InFile<ast::MacroRules>,
+    ) -> Option<MacroDefId> {
         let kind = MacroDefKind::Declarative;
         let file_id = src.file_id.original_file(self.db.upcast());
         let krate = self.file_to_def(file_id)?.krate;

crates/hir/src/semantics/source_to_def.rs

@@ -566,66 +566,52 @@ impl ExprCollector<'_> {
         syntax_ptr: AstPtr<ast::Expr>,
         mut collector: F,
     ) {
-        if let Some(name) = e.is_macro_rules().map(|it| it.as_name()) {
-            let mac = MacroDefId {
-                krate: Some(self.expander.module.krate),
-                ast_id: Some(self.expander.ast_id(&e)),
-                kind: MacroDefKind::Declarative,
-                local_inner: false,
-            };
-            self.body.item_scope.define_legacy_macro(name, mac);
+        // File containing the macro call. Expansion errors will be attached here.
+        let outer_file = self.expander.current_file_id;
 
-            // FIXME: do we still need to allocate this as missing ?
-            collector(self, None);
-        } else {
-            // File containing the macro call. Expansion errors will be attached here.
-            let outer_file = self.expander.current_file_id;
-
-            let macro_call = self.expander.to_source(AstPtr::new(&e));
-            let res = self.expander.enter_expand(self.db, Some(&self.body.item_scope), e);
-
-            match &res.err {
-                Some(ExpandError::UnresolvedProcMacro) => {
-                    self.source_map.diagnostics.push(BodyDiagnostic::UnresolvedProcMacro(
-                        UnresolvedProcMacro {
-                            file: outer_file,
-                            node: syntax_ptr.into(),
-                            precise_location: None,
-                            macro_name: None,
-                        },
-                    ));
-                }
-                Some(err) => {
-                    self.source_map.diagnostics.push(BodyDiagnostic::MacroError(MacroError {
+        let macro_call = self.expander.to_source(AstPtr::new(&e));
+        let res = self.expander.enter_expand(self.db, Some(&self.body.item_scope), e);
+
+        match &res.err {
+            Some(ExpandError::UnresolvedProcMacro) => {
+                self.source_map.diagnostics.push(BodyDiagnostic::UnresolvedProcMacro(
+                    UnresolvedProcMacro {
                         file: outer_file,
                         node: syntax_ptr.into(),
-                        message: err.to_string(),
-                    }));
-                }
-                None => {}
+                        precise_location: None,
+                        macro_name: None,
+                    },
+                ));
+            }
+            Some(err) => {
+                self.source_map.diagnostics.push(BodyDiagnostic::MacroError(MacroError {
+                    file: outer_file,
+                    node: syntax_ptr.into(),
+                    message: err.to_string(),
+                }));
             }
+            None => {}
+        }
 
-            match res.value {
-                Some((mark, expansion)) => {
-                    // FIXME: Statements are too complicated to recover from error for now.
-                    // It is because we don't have any hygenine for local variable expansion right now.
-                    if T::can_cast(syntax::SyntaxKind::MACRO_STMTS) && res.err.is_some() {
-                        self.expander.exit(self.db, mark);
-                        collector(self, None);
-                    } else {
-                        self.source_map
-                            .expansions
-                            .insert(macro_call, self.expander.current_file_id);
+        match res.value {
+            Some((mark, expansion)) => {
+                // FIXME: Statements are too complicated to recover from error for now.
+                // It is because we don't have any hygenine for local variable expansion right now.
+                if T::can_cast(syntax::SyntaxKind::MACRO_STMTS) && res.err.is_some() {
+                    self.expander.exit(self.db, mark);
+                    collector(self, None);
+                } else {
+                    self.source_map.expansions.insert(macro_call, self.expander.current_file_id);
 
-                        let item_tree = self.db.item_tree(self.expander.current_file_id);
-                        self.item_trees.insert(self.expander.current_file_id, item_tree);
+                    let item_tree = self.db.item_tree(self.expander.current_file_id);
+                    self.item_trees.insert(self.expander.current_file_id, item_tree);
 
-                        collector(self, Some(expansion));
-                        self.expander.exit(self.db, mark);
-                    }
+                    let id = collector(self, Some(expansion));
+                    self.expander.exit(self.db, mark);
+                    id
                 }
-                None => collector(self, None),
             }
+            None => collector(self, None),
         }
     }
 
@@ -785,26 +771,44 @@ impl ExprCollector<'_> {
                     | ast::Item::ExternCrate(_)
                     | ast::Item::Module(_)
                     | ast::Item::MacroCall(_) => return None,
+                    ast::Item::MacroRules(def) => {
+                        return Some(Either::Right(def));
+                    }
                 };
 
-                Some((def, name))
+                Some(Either::Left((def, name)))
             })
             .collect::<Vec<_>>();
 
-        for (def, name) in items {
-            self.body.item_scope.define_def(def);
-            if let Some(name) = name {
-                let vis = crate::visibility::Visibility::Public; // FIXME determine correctly
-                let has_constructor = match def {
-                    ModuleDefId::AdtId(AdtId::StructId(s)) => {
-                        self.db.struct_data(s).variant_data.kind() != StructKind::Record
+        for either in items {
+            match either {
+                Either::Left((def, name)) => {
+                    self.body.item_scope.define_def(def);
+                    if let Some(name) = name {
+                        let vis = crate::visibility::Visibility::Public; // FIXME determine correctly
+                        let has_constructor = match def {
+                            ModuleDefId::AdtId(AdtId::StructId(s)) => {
+                                self.db.struct_data(s).variant_data.kind() != StructKind::Record
+                            }
+                            _ => true,
+                        };
+                        self.body.item_scope.push_res(
+                            name.as_name(),
+                            crate::per_ns::PerNs::from_def(def, vis, has_constructor),
+                        );
                     }
-                    _ => true,
-                };
-                self.body.item_scope.push_res(
-                    name.as_name(),
-                    crate::per_ns::PerNs::from_def(def, vis, has_constructor),
-                );
+                }
+                Either::Right(e) => {
+                    let mac = MacroDefId {
+                        krate: Some(self.expander.module.krate),
+                        ast_id: Some(self.expander.ast_id(&e)),
+                        kind: MacroDefKind::Declarative,
+                        local_inner: false,
+                    };
+                    if let Some(name) = e.name() {
+                        self.body.item_scope.define_legacy_macro(name.as_name(), mac);
+                    }
+                }
             }
         }
     }

crates/hir_def/src/body/lower.rs

@@ -142,6 +142,7 @@ impl ItemTree {
                 type_aliases,
                 mods,
                 macro_calls,
+                macro_rules,
                 exprs,
                 vis,
                 generics,
@@ -162,6 +163,7 @@ impl ItemTree {
             type_aliases.shrink_to_fit();
             mods.shrink_to_fit();
             macro_calls.shrink_to_fit();
+            macro_rules.shrink_to_fit();
             exprs.shrink_to_fit();
 
             vis.arena.shrink_to_fit();
@@ -280,6 +282,7 @@ struct ItemTreeData {
     type_aliases: Arena<TypeAlias>,
     mods: Arena<Mod>,
     macro_calls: Arena<MacroCall>,
+    macro_rules: Arena<MacroRules>,
     exprs: Arena<Expr>,
 
     vis: ItemVisibilities,
@@ -427,6 +430,7 @@ mod_items! {
     TypeAlias in type_aliases -> ast::TypeAlias,
     Mod in mods -> ast::Module,
     MacroCall in macro_calls -> ast::MacroCall,
+    MacroRules in macro_rules -> ast::MacroRules,
 }
 
 macro_rules! impl_index {
@@ -629,17 +633,22 @@ pub enum ModKind {
 
 #[derive(Debug, Clone, Eq, PartialEq)]
 pub struct MacroCall {
-    /// For `macro_rules!` declarations, this is the name of the declared macro.
-    pub name: Option<Name>,
     /// Path to the called macro.
     pub path: ModPath,
+    pub ast_id: FileAstId<ast::MacroCall>,
+}
+
+#[derive(Debug, Clone, Eq, PartialEq)]
+pub struct MacroRules {
+    /// For `macro_rules!` declarations, this is the name of the declared macro.
+    pub name: Name,
     /// Has `#[macro_export]`.
     pub is_export: bool,
     /// Has `#[macro_export(local_inner_macros)]`.
     pub is_local_inner: bool,
     /// Has `#[rustc_builtin_macro]`.
     pub is_builtin: bool,
-    pub ast_id: FileAstId<ast::MacroCall>,
+    pub ast_id: FileAstId<ast::MacroRules>,
 }
 
 // NB: There's no `FileAstId` for `Expr`. The only case where this would be useful is for array
@@ -670,7 +679,8 @@ impl ModItem {
             | ModItem::Static(_)
             | ModItem::Trait(_)
             | ModItem::Impl(_)
-            | ModItem::Mod(_) => None,
+            | ModItem::Mod(_)
+            | ModItem::MacroRules(_) => None,
             ModItem::MacroCall(call) => Some(AssocItem::MacroCall(*call)),
             ModItem::Const(konst) => Some(AssocItem::Const(*konst)),
             ModItem::TypeAlias(alias) => Some(AssocItem::TypeAlias(*alias)),
@@ -697,6 +707,7 @@ impl ModItem {
             ModItem::TypeAlias(it) => tree[it.index].ast_id().upcast(),
             ModItem::Mod(it) => tree[it.index].ast_id().upcast(),
             ModItem::MacroCall(it) => tree[it.index].ast_id().upcast(),
+            ModItem::MacroRules(it) => tree[it.index].ast_id().upcast(),
         }
     }
 }

crates/hir_def/src/item_tree.rs

@@ -84,8 +84,7 @@ impl Ctx {
             | ast::Item::Fn(_)
             | ast::Item::TypeAlias(_)
             | ast::Item::Const(_)
-            | ast::Item::Static(_)
-            | ast::Item::MacroCall(_) => {
+            | ast::Item::Static(_) => {
                 // Skip this if we're already collecting inner items. We'll descend into all nodes
                 // already.
                 if !inner {
@@ -98,7 +97,11 @@ impl Ctx {
             ast::Item::Trait(_) | ast::Item::Impl(_) | ast::Item::ExternBlock(_) => {}
 
             // These don't have inner items.
-            ast::Item::Module(_) | ast::Item::ExternCrate(_) | ast::Item::Use(_) => {}
+            ast::Item::Module(_)
+            | ast::Item::ExternCrate(_)
+            | ast::Item::Use(_)
+            | ast::Item::MacroCall(_)
+            | ast::Item::MacroRules(_) => {}
         };
 
         let attrs = Attrs::new(item, &self.hygiene);
@@ -118,6 +121,7 @@ impl Ctx {
             )),
             ast::Item::ExternCrate(ast) => self.lower_extern_crate(ast).map(Into::into),
             ast::Item::MacroCall(ast) => self.lower_macro_call(ast).map(Into::into),
+            ast::Item::MacroRules(ast) => self.lower_macro_rules(ast).map(Into::into),
             ast::Item::ExternBlock(ast) => {
                 Some(ModItems(self.lower_extern_block(ast).into_iter().collect::<SmallVec<_>>()))
             }
@@ -525,9 +529,15 @@ impl Ctx {
     }
 
     fn lower_macro_call(&mut self, m: &ast::MacroCall) -> Option<FileItemTreeId<MacroCall>> {
-        let name = m.name().map(|it| it.as_name());
-        let attrs = Attrs::new(m, &self.hygiene);
         let path = ModPath::from_src(m.path()?, &self.hygiene)?;
+        let ast_id = self.source_ast_id_map.ast_id(m);
+        let res = MacroCall { path, ast_id };
+        Some(id(self.data().macro_calls.alloc(res)))
+    }
+
+    fn lower_macro_rules(&mut self, m: &ast::MacroRules) -> Option<FileItemTreeId<MacroRules>> {
+        let name = m.name().map(|it| it.as_name())?;
+        let attrs = Attrs::new(m, &self.hygiene);
 
         let ast_id = self.source_ast_id_map.ast_id(m);
 
@@ -547,8 +557,8 @@ impl Ctx {
         };
 
         let is_builtin = attrs.by_key("rustc_builtin_macro").exists();
-        let res = MacroCall { name, path, is_export, is_builtin, is_local_inner, ast_id };
-        Some(id(self.data().macro_calls.alloc(res)))
+        let res = MacroRules { name, is_export, is_builtin, is_local_inner, ast_id };
+        Some(id(self.data().macro_rules.alloc(res)))
     }
 
     fn lower_extern_block(&mut self, block: &ast::ExternBlock) -> Vec<ModItem> {