expand: Move some more derive logic to rustc_builtin_macros

Author: petrochenkov

Diff for: compiler/rustc_builtin_macros/src/cfg_eval.rs

@@ -24,19 +24,18 @@ crate fn expand(
     annotatable: Annotatable,
 ) -> Vec<Annotatable> {
     check_builtin_macro_attribute(ecx, meta_item, sym::cfg_eval);
-    cfg_eval(ecx, annotatable)
+    vec![cfg_eval(ecx, annotatable)]
 }
 
-crate fn cfg_eval(ecx: &ExtCtxt<'_>, annotatable: Annotatable) -> Vec<Annotatable> {
-    let mut visitor = CfgEval {
+crate fn cfg_eval(ecx: &ExtCtxt<'_>, annotatable: Annotatable) -> Annotatable {
+    CfgEval {
         cfg: &mut StripUnconfigured {
             sess: ecx.sess,
             features: ecx.ecfg.features,
             config_tokens: true,
         },
-    };
-    let annotatable = visitor.configure_annotatable(annotatable);
-    vec![annotatable]
+    }
+    .configure_annotatable(annotatable)
 }
 
 struct CfgEval<'a, 'b> {

Diff for: compiler/rustc_builtin_macros/src/derive.rs

@@ -26,6 +26,8 @@ impl MultiItemModifier for Expander {
             return ExpandResult::Ready(vec![item]);
         }
 
+        let item = cfg_eval(ecx, item);
+
         let result =
             ecx.resolver.resolve_derives(ecx.current_expansion.id, ecx.force_mode, &|| {
                 let template =
@@ -54,12 +56,12 @@ impl MultiItemModifier for Expander {
                         report_path_args(sess, &meta);
                         meta.path
                     })
-                    .map(|path| (path, None))
+                    .map(|path| (path, item.clone(), None))
                     .collect()
             });
 
         match result {
-            Ok(()) => ExpandResult::Ready(cfg_eval(ecx, item)),
+            Ok(()) => ExpandResult::Ready(vec![item]),
             Err(Indeterminate) => ExpandResult::Retry(item),
         }
     }

Diff for: compiler/rustc_expand/src/base.rs

@@ -835,7 +835,7 @@ impl SyntaxExtension {
 /// Error type that denotes indeterminacy.
 pub struct Indeterminate;
 
-pub type DeriveResolutions = Vec<(ast::Path, Option<Lrc<SyntaxExtension>>)>;
+pub type DeriveResolutions = Vec<(ast::Path, Annotatable, Option<Lrc<SyntaxExtension>>)>;
 
 pub trait ResolverExpand {
     fn next_node_id(&mut self) -> NodeId;

Diff for: compiler/rustc_expand/src/expand.rs

@@ -500,42 +500,16 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
                         .resolver
                         .take_derive_resolutions(expn_id)
                         .map(|derives| {
-                            enum AnnotatableRef<'a> {
-                                Item(&'a P<ast::Item>),
-                                Stmt(&'a ast::Stmt),
-                            }
-                            let item = match &fragment {
-                                AstFragment::Items(items) => match &items[..] {
-                                    [item] => AnnotatableRef::Item(item),
-                                    _ => unreachable!(),
-                                },
-                                AstFragment::Stmts(stmts) => match &stmts[..] {
-                                    [stmt] => AnnotatableRef::Stmt(stmt),
-                                    _ => unreachable!(),
-                                },
-                                _ => unreachable!(),
-                            };
-
                             derive_invocations.reserve(derives.len());
                             derives
                                 .into_iter()
-                                .map(|(path, _exts)| {
+                                .map(|(path, item, _exts)| {
                                     // FIXME: Consider using the derive resolutions (`_exts`)
                                     // instead of enqueuing the derives to be resolved again later.
                                     let expn_id = ExpnId::fresh(None);
                                     derive_invocations.push((
                                         Invocation {
-                                            kind: InvocationKind::Derive {
-                                                path,
-                                                item: match item {
-                                                    AnnotatableRef::Item(item) => {
-                                                        Annotatable::Item(item.clone())
-                                                    }
-                                                    AnnotatableRef::Stmt(stmt) => {
-                                                        Annotatable::Stmt(P(stmt.clone()))
-                                                    }
-                                                },
-                                            },
+                                            kind: InvocationKind::Derive { path, item },
                                             fragment_kind,
                                             expansion_data: ExpansionData {
                                                 id: expn_id,

Diff for: compiler/rustc_resolve/src/macros.rs

@@ -380,7 +380,7 @@ impl<'a> ResolverExpand for Resolver<'a> {
             has_derive_copy: false,
         });
         let parent_scope = self.invocation_parent_scopes[&expn_id];
-        for (i, (path, opt_ext)) in entry.resolutions.iter_mut().enumerate() {
+        for (i, (path, _, opt_ext)) in entry.resolutions.iter_mut().enumerate() {
             if opt_ext.is_none() {
                 *opt_ext = Some(
                     match self.resolve_macro_path(