Merge #9128

9128: feat: expand procedural attribute macros r=jonas-schievink a=jonas-schievink

This adds experimental support for attribute macros. They can be enabled by setting `rust-analyzer.experimental.procAttrMacros` to `true`.

Known issues:
* Tokens aren't remapped, presumably because we edit the input syntax tree (this causes IDE features to not work inside items with attribute macros on them)
* Macro errors aren't reported correctly

Closes #8971
Fixes #8964 / la10736/rstest#120
Fixes #2984
Fixes #5412
Fixes #6029
Fixes #6687

#6740 is still not fixed – we now expand `#[proc_macro_hack]`, but fail to expand the resulting `proc_macro_call!()` macro.

Co-authored-by: Jonas Schievink <jonasschievink@gmail.com>

Author: bors[bot]

crates/hir/src/lib.rs

@@ -534,6 +534,18 @@ impl Module {
                                 Some(derive_name.clone()),
                             )
                         }
+                        MacroCallKind::Attr { ast_id, invoc_attr_index, attr_name, .. } => {
+                            let node = ast_id.to_node(db.upcast());
+                            let attr =
+                                node.attrs().nth((*invoc_attr_index) as usize).unwrap_or_else(
+                                    || panic!("cannot find attribute #{}", invoc_attr_index),
+                                );
+                            (
+                                ast_id.file_id,
+                                SyntaxNodePtr::from(AstPtr::new(&attr)),
+                                Some(attr_name.clone()),
+                            )
+                        }
                     };
                     sink.push(UnresolvedProcMacro {
                         file,
@@ -558,7 +570,9 @@ impl Module {
                             let node = ast_id.to_node(db.upcast());
                             (ast_id.file_id, SyntaxNodePtr::from(AstPtr::new(&node)))
                         }
-                        MacroCallKind::Derive { ast_id, .. } => {
+                        MacroCallKind::Derive { ast_id, .. }
+                        | MacroCallKind::Attr { ast_id, .. } => {
+                            // FIXME: point to the attribute instead, this creates very large diagnostics
                             let node = ast_id.to_node(db.upcast());
                             (ast_id.file_id, SyntaxNodePtr::from(AstPtr::new(&node)))
                         }

crates/hir_def/src/builtin_attr.rs

@@ -2,7 +2,7 @@
 //!
 //! The actual definitions were copied from rustc's `compiler/rustc_feature/src/builtin_attrs.rs`.
 //!
-//! It was last synchronized with upstream commit 2225ee1b62ff089917434aefd9b2bf509cfa087f.
+//! It was last synchronized with upstream commit 835150e70288535bc57bb624792229b9dc94991d.
 //!
 //! The macros were adjusted to only expand to the attribute name, since that is all we need to do
 //! name resolution, and `BUILTIN_ATTRIBUTES` is almost entirely unchanged from the original, to
@@ -58,7 +58,6 @@ pub const INERT_ATTRIBUTES: &[BuiltinAttribute] = &[
     ungated!(reexport_test_harness_main, Normal, template!(NameValueStr: "name")),
 
     // Macros:
-    ungated!(derive, Normal, template!(List: "Trait1, Trait2, ...")),
     ungated!(automatically_derived, Normal, template!(Word)),
     // FIXME(#14407)
     ungated!(macro_use, Normal, template!(Word, List: "name1, name2, ...")),
@@ -98,8 +97,8 @@ pub const INERT_ATTRIBUTES: &[BuiltinAttribute] = &[
         template!(List: r#"name = "...", /*opt*/ kind = "dylib|static|...", /*opt*/ wasm_import_module = "...""#),
     ),
     ungated!(link_name, AssumedUsed, template!(NameValueStr: "name")),
-    ungated!(no_link, Normal, template!(Word)),
-    ungated!(repr, Normal, template!(List: "C")),
+    ungated!(no_link, AssumedUsed, template!(Word)),
+    ungated!(repr, AssumedUsed, template!(List: "C")),
     ungated!(export_name, AssumedUsed, template!(NameValueStr: "name")),
     ungated!(link_section, AssumedUsed, template!(NameValueStr: "name")),
     ungated!(no_mangle, AssumedUsed, template!(Word)),
@@ -112,6 +111,10 @@ pub const INERT_ATTRIBUTES: &[BuiltinAttribute] = &[
         const_eval_limit, CrateLevel, template!(NameValueStr: "N"), const_eval_limit,
         experimental!(const_eval_limit)
     ),
+    gated!(
+        move_size_limit, CrateLevel, template!(NameValueStr: "N"), large_assignments,
+        experimental!(move_size_limit)
+    ),
 
     // Entry point:
     ungated!(main, Normal, template!(Word)),
@@ -140,6 +143,7 @@ pub const INERT_ATTRIBUTES: &[BuiltinAttribute] = &[
         template!(List: "address, memory, thread"),
         experimental!(no_sanitize)
     ),
+    gated!(no_coverage, AssumedUsed, template!(Word), experimental!(no_coverage)),
 
     // FIXME: #14408 assume docs are used since rustdoc looks at them.
     ungated!(doc, AssumedUsed, template!(List: "hidden|inline|...", NameValueStr: "string")),
@@ -150,11 +154,6 @@ pub const INERT_ATTRIBUTES: &[BuiltinAttribute] = &[
 
     // Linking:
     gated!(naked, AssumedUsed, template!(Word), naked_functions, experimental!(naked)),
-    gated!(
-        link_args, Normal, template!(NameValueStr: "args"),
-        "the `link_args` attribute is experimental and not portable across platforms, \
-        it is recommended to use `#[link(name = \"foo\")] instead",
-    ),
     gated!(
         link_ordinal, AssumedUsed, template!(List: "ordinal"), raw_dylib,
         experimental!(link_ordinal)
@@ -172,7 +171,7 @@ pub const INERT_ATTRIBUTES: &[BuiltinAttribute] = &[
         "custom test frameworks are an unstable feature",
     ),
     // RFC #1268
-    gated!(marker, Normal, template!(Word), marker_trait_attr, experimental!(marker)),
+    gated!(marker, AssumedUsed, template!(Word), marker_trait_attr, experimental!(marker)),
     gated!(
         thread_local, AssumedUsed, template!(Word),
         "`#[thread_local]` is an experimental feature, and does not currently handle destructors",
@@ -291,7 +290,7 @@ pub const INERT_ATTRIBUTES: &[BuiltinAttribute] = &[
     // Internal attributes, Macro related:
     // ==========================================================================
 
-    rustc_attr!(rustc_builtin_macro, AssumedUsed, template!(Word), IMPL_DETAIL),
+    rustc_attr!(rustc_builtin_macro, AssumedUsed, template!(Word, NameValueStr: "name"), IMPL_DETAIL),
     rustc_attr!(rustc_proc_macro_decls, Normal, template!(Word), INTERNAL_UNSTABLE),
     rustc_attr!(
         rustc_macro_transparency, AssumedUsed,
@@ -319,7 +318,7 @@ pub const INERT_ATTRIBUTES: &[BuiltinAttribute] = &[
     // ==========================================================================
 
     rustc_attr!(rustc_promotable, AssumedUsed, template!(Word), IMPL_DETAIL),
-    rustc_attr!(rustc_args_required_const, AssumedUsed, template!(List: "N"), INTERNAL_UNSTABLE),
+    rustc_attr!(rustc_legacy_const_generics, AssumedUsed, template!(List: "N"), INTERNAL_UNSTABLE),
 
     // ==========================================================================
     // Internal attributes, Layout related:
@@ -380,13 +379,23 @@ pub const INERT_ATTRIBUTES: &[BuiltinAttribute] = &[
         rustc_specialization_trait, Normal, template!(Word),
         "the `#[rustc_specialization_trait]` attribute is used to check specializations"
     ),
+    rustc_attr!(
+        rustc_main, Normal, template!(Word),
+        "the `#[rustc_main]` attribute is used internally to specify test entry point function",
+    ),
+    rustc_attr!(
+        rustc_skip_array_during_method_dispatch, Normal, template!(Word),
+        "the `#[rustc_skip_array_during_method_dispatch]` attribute is used to exclude a trait \
+        from method dispatch when the receiver is an array, for compatibility in editions < 2021."
+    ),
 
     // ==========================================================================
     // Internal attributes, Testing:
     // ==========================================================================
 
     rustc_attr!(TEST, rustc_outlives, Normal, template!(Word)),
     rustc_attr!(TEST, rustc_capture_analysis, Normal, template!(Word)),
+    rustc_attr!(TEST, rustc_insignificant_dtor, Normal, template!(Word)),
     rustc_attr!(TEST, rustc_variance, Normal, template!(Word)),
     rustc_attr!(TEST, rustc_layout, Normal, template!(List: "field1, field2, ...")),
     rustc_attr!(TEST, rustc_regions, Normal, template!(Word)),
@@ -395,12 +404,9 @@ pub const INERT_ATTRIBUTES: &[BuiltinAttribute] = &[
         template!(Word, List: "delay_span_bug_from_inside_query")
     ),
     rustc_attr!(TEST, rustc_dump_user_substs, AssumedUsed, template!(Word)),
+    rustc_attr!(TEST, rustc_evaluate_where_clauses, AssumedUsed, template!(Word)),
     rustc_attr!(TEST, rustc_if_this_changed, AssumedUsed, template!(Word, List: "DepNode")),
     rustc_attr!(TEST, rustc_then_this_would_need, AssumedUsed, template!(List: "DepNode")),
-    rustc_attr!(
-        TEST, rustc_dirty, AssumedUsed,
-        template!(List: r#"cfg = "...", /*opt*/ label = "...", /*opt*/ except = "...""#),
-    ),
     rustc_attr!(
         TEST, rustc_clean, AssumedUsed,
         template!(List: r#"cfg = "...", /*opt*/ label = "...", /*opt*/ except = "...""#),

crates/hir_def/src/db.rs

@@ -51,6 +51,9 @@ pub trait InternDatabase: SourceDatabase {
 
 #[salsa::query_group(DefDatabaseStorage)]
 pub trait DefDatabase: InternDatabase + AstDatabase + Upcast<dyn AstDatabase> {
+    #[salsa::input]
+    fn enable_proc_attr_macros(&self) -> bool;
+
     #[salsa::invoke(ItemTree::file_item_tree_query)]
     fn file_item_tree(&self, file_id: HirFileId) -> Arc<ItemTree>;
 

crates/hir_def/src/lib.rs

@@ -55,6 +55,7 @@ use std::{
     sync::Arc,
 };
 
+use attr::Attr;
 use base_db::{impl_intern_key, salsa, CrateId};
 use hir_expand::{
     ast_id_map::FileAstId,
@@ -768,3 +769,42 @@ fn derive_macro_as_call_id(
         .into();
     Ok(res)
 }
+
+fn attr_macro_as_call_id(
+    item_attr: &AstIdWithPath<ast::Item>,
+    macro_attr: &Attr,
+    db: &dyn db::DefDatabase,
+    krate: CrateId,
+    resolver: impl Fn(path::ModPath) -> Option<MacroDefId>,
+) -> Result<MacroCallId, UnresolvedMacro> {
+    let def: MacroDefId = resolver(item_attr.path.clone())
+        .ok_or_else(|| UnresolvedMacro { path: item_attr.path.clone() })?;
+    let last_segment = item_attr
+        .path
+        .segments()
+        .last()
+        .ok_or_else(|| UnresolvedMacro { path: item_attr.path.clone() })?;
+    let mut arg = match &macro_attr.input {
+        Some(input) => match &**input {
+            attr::AttrInput::Literal(_) => tt::Subtree::default(),
+            attr::AttrInput::TokenTree(tt) => tt.clone(),
+        },
+        None => tt::Subtree::default(),
+    };
+    // The parentheses are always disposed here.
+    arg.delimiter = None;
+
+    let res = def
+        .as_lazy_macro(
+            db.upcast(),
+            krate,
+            MacroCallKind::Attr {
+                ast_id: item_attr.ast_id,
+                attr_name: last_segment.to_string(),
+                attr_args: arg,
+                invoc_attr_index: macro_attr.id.ast_index,
+            },
+        )
+        .into();
+    Ok(res)
+}

crates/hir_def/src/nameres/collector.rs

@@ -23,7 +23,7 @@ use syntax::ast;
 
 use crate::{
     attr::{Attr, AttrId, AttrInput, Attrs},
-    builtin_attr,
+    attr_macro_as_call_id, builtin_attr,
     db::DefDatabase,
     derive_macro_as_call_id,
     intern::Interned,
@@ -223,7 +223,7 @@ struct MacroDirective {
 enum MacroDirectiveKind {
     FnLike { ast_id: AstIdWithPath<ast::MacroCall>, fragment: FragmentKind },
     Derive { ast_id: AstIdWithPath<ast::Item>, derive_attr: AttrId },
-    Attr { ast_id: AstIdWithPath<ast::Item>, attr: AttrId, mod_item: ModItem },
+    Attr { ast_id: AstIdWithPath<ast::Item>, attr: Attr, mod_item: ModItem },
 }
 
 struct DefData<'a> {
@@ -419,7 +419,7 @@ impl DefCollector<'_> {
         let mut unresolved_macros = std::mem::replace(&mut self.unresolved_macros, Vec::new());
         let pos = unresolved_macros.iter().position(|directive| {
             if let MacroDirectiveKind::Attr { ast_id, mod_item, attr } = &directive.kind {
-                self.skip_attrs.insert(ast_id.ast_id.with_value(*mod_item), *attr);
+                self.skip_attrs.insert(ast_id.ast_id.with_value(*mod_item), attr.id);
 
                 let file_id = ast_id.ast_id.file_id;
                 let item_tree = self.db.file_item_tree(file_id);
@@ -1050,7 +1050,7 @@ impl DefCollector<'_> {
                                 let file_id = ast_id.ast_id.file_id;
                                 let item_tree = self.db.file_item_tree(file_id);
                                 let mod_dir = self.mod_dirs[&directive.module_id].clone();
-                                self.skip_attrs.insert(InFile::new(file_id, *mod_item), *attr);
+                                self.skip_attrs.insert(InFile::new(file_id, *mod_item), attr.id);
                                 ModCollector {
                                     def_collector: &mut *self,
                                     macro_depth: directive.depth,
@@ -1067,8 +1067,56 @@ impl DefCollector<'_> {
                         }
                     }
 
+                    if !self.db.enable_proc_attr_macros() {
+                        return true;
+                    }
+
                     // Not resolved to a derive helper, so try to resolve as a macro.
-                    // FIXME: not yet :)
+                    match attr_macro_as_call_id(
+                        ast_id,
+                        attr,
+                        self.db,
+                        self.def_map.krate,
+                        &resolver,
+                    ) {
+                        Ok(call_id) => {
+                            let loc: MacroCallLoc = self.db.lookup_intern_macro(call_id);
+                            if let MacroDefKind::ProcMacro(exp, ..) = &loc.def.kind {
+                                if exp.is_dummy() {
+                                    // Proc macros that cannot be expanded are treated as not
+                                    // resolved, in order to fall back later.
+                                    self.def_map.diagnostics.push(
+                                        DefDiagnostic::unresolved_proc_macro(
+                                            directive.module_id,
+                                            loc.kind,
+                                        ),
+                                    );
+
+                                    let file_id = ast_id.ast_id.file_id;
+                                    let item_tree = self.db.file_item_tree(file_id);
+                                    let mod_dir = self.mod_dirs[&directive.module_id].clone();
+                                    self.skip_attrs
+                                        .insert(InFile::new(file_id, *mod_item), attr.id);
+                                    ModCollector {
+                                        def_collector: &mut *self,
+                                        macro_depth: directive.depth,
+                                        module_id: directive.module_id,
+                                        file_id,
+                                        item_tree: &item_tree,
+                                        mod_dir,
+                                    }
+                                    .collect(&[*mod_item]);
+
+                                    // Remove the macro directive.
+                                    return false;
+                                }
+                            }
+                            resolved.push((directive.module_id, call_id, directive.depth));
+                            res = ReachedFixedPoint::No;
+                            return false;
+                        }
+                        Err(UnresolvedMacro { .. }) => (),
+                    }
                 }
             }
 
@@ -1628,7 +1676,7 @@ impl ModCollector<'_, '_> {
                 self.def_collector.unresolved_macros.push(MacroDirective {
                     module_id: self.module_id,
                     depth: self.macro_depth + 1,
-                    kind: MacroDirectiveKind::Attr { ast_id, attr: attr.id, mod_item },
+                    kind: MacroDirectiveKind::Attr { ast_id, attr: attr.clone(), mod_item },
                 });
 
                 return Err(());

crates/hir_def/src/test_db.rs

@@ -30,12 +30,19 @@ use crate::{
     crate::db::InternDatabaseStorage,
     crate::db::DefDatabaseStorage
 )]
-#[derive(Default)]
 pub(crate) struct TestDB {
     storage: salsa::Storage<TestDB>,
     events: Mutex<Option<Vec<salsa::Event>>>,
 }
 
+impl Default for TestDB {
+    fn default() -> Self {
+        let mut this = Self { storage: Default::default(), events: Default::default() };
+        this.set_enable_proc_attr_macros(true);
+        this
+    }
+}
+
 impl Upcast<dyn AstDatabase> for TestDB {
     fn upcast(&self) -> &(dyn AstDatabase + 'static) {
         &*self

crates/hir_expand/src/db.rs

@@ -13,8 +13,8 @@ use syntax::{
 
 use crate::{
     ast_id_map::AstIdMap, hygiene::HygieneFrame, input::process_macro_input, BuiltinDeriveExpander,
-    BuiltinFnLikeExpander, HirFileId, HirFileIdRepr, MacroCallId, MacroCallLoc, MacroDefId,
-    MacroDefKind, MacroFile, ProcMacroExpander,
+    BuiltinFnLikeExpander, HirFileId, HirFileIdRepr, MacroCallId, MacroCallKind, MacroCallLoc,
+    MacroDefId, MacroDefKind, MacroFile, ProcMacroExpander,
 };
 
 /// Total limit on the number of tokens produced by any macro invocation.
@@ -377,7 +377,12 @@ fn expand_proc_macro(
         _ => unreachable!(),
     };
 
-    expander.expand(db, loc.krate, &macro_arg.0)
+    let attr_arg = match &loc.kind {
+        MacroCallKind::Attr { attr_args, .. } => Some(attr_args),
+        _ => None,
+    };
+
+    expander.expand(db, loc.krate, &macro_arg.0, attr_arg)
 }
 
 fn is_self_replicating(from: &SyntaxNode, to: &SyntaxNode) -> bool {

crates/hir_expand/src/input.rs

@@ -28,6 +28,14 @@ pub(crate) fn process_macro_input(
 
             remove_derives_up_to(item, derive_attr_index as usize).syntax().clone()
         }
+        MacroCallKind::Attr { invoc_attr_index, .. } => {
+            let item = match ast::Item::cast(node.clone()) {
+                Some(item) => item,
+                None => return node,
+            };
+
+            remove_attr_invoc(item, invoc_attr_index as usize).syntax().clone()
+        }
     }
 }
 
@@ -46,6 +54,17 @@ fn remove_derives_up_to(item: ast::Item, attr_index: usize) -> ast::Item {
     item
 }
 
+/// Removes the attribute invoking an attribute macro from `item`.
+fn remove_attr_invoc(item: ast::Item, attr_index: usize) -> ast::Item {
+    let item = item.clone_for_update();
+    let attr = item
+        .attrs()
+        .nth(attr_index)
+        .unwrap_or_else(|| panic!("cannot find attribute #{}", attr_index));
+    attr.syntax().detach();
+    item
+}
+
 #[cfg(test)]
 mod tests {
     use base_db::fixture::WithFixture;