Switch to a bitflags `MacroKinds` to support macros with more than one kind

Review everything that uses `MacroKind`, and switch anything that could
refer to more than one kind to use `MacroKinds`.

Add a new `SyntaxExtensionKind::MacroRules` for `macro_rules!` macros,
using the concrete `MacroRulesMacroExpander` type, and have it track
which kinds it can handle. Eliminate the separate optional `attr_ext`,
now that a `SyntaxExtension` can handle multiple macro kinds.

This also avoids the need to downcast when calling methods on
`MacroRulesMacroExpander`, such as `get_unused_rule`.

Integrate macro kind checking into name resolution's
`sub_namespace_match`, so that we only find a macro if it's the right
type, and eliminate the special-case hack for attributes.

1 files changed, 3 insertions, 13 deletions

diff --git a/compiler/rustc_resolve/src/ident.rs b/compiler/rustc_resolve/src/ident.rs
index 9efcef695b7..87b3fc76c96 100644
--- a/compiler/rustc_resolve/src/ident.rs
+++ b/compiler/rustc_resolve/src/ident.rs
@@ -2,7 +2,7 @@ use Determinacy::*;
 use Namespace::*;
 use rustc_ast::{self as ast, NodeId};
 use rustc_errors::ErrorGuaranteed;
-use rustc_hir::def::{DefKind, Namespace, NonMacroAttrKind, PartialRes, PerNS};
+use rustc_hir::def::{DefKind, MacroKinds, Namespace, NonMacroAttrKind, PartialRes, PerNS};
 use rustc_middle::bug;
 use rustc_session::lint::BuiltinLintDiag;
 use rustc_session::lint::builtin::PROC_MACRO_DERIVE_RESOLUTION_FALLBACK;
@@ -259,7 +259,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
         {
             let ext = &self.get_macro_by_def_id(def_id).ext;
             if ext.builtin_name.is_none()
-                && ext.macro_kind() == MacroKind::Derive
+                && ext.macro_kinds() == MacroKinds::DERIVE
                 && parent.expansion.outer_expn_is_descendant_of(*ctxt)
             {
                 return Some((parent, derive_fallback_lint_id));
@@ -632,17 +632,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
 
                 match result {
                     Ok((binding, flags)) => {
-                        let binding_macro_kind = binding.macro_kind();
-                        // If we're looking for an attribute, that might be supported by a
-                        // `macro_rules!` macro.
-                        // FIXME: Replace this with tracking multiple macro kinds for one Def.
-                        if !(sub_namespace_match(binding_macro_kind, macro_kind)
-                            || (binding_macro_kind == Some(MacroKind::Bang)
-                                && macro_kind == Some(MacroKind::Attr)
-                                && this
-                                    .get_macro(binding.res())
-                                    .is_some_and(|macro_data| macro_data.attr_ext.is_some())))
-                        {
+                        if !sub_namespace_match(binding.macro_kinds(), macro_kind) {
                             return None;
                         }