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.

3 files changed, 24 insertions, 6 deletions

diff --git a/compiler/rustc_metadata/src/rmeta/encoder.rs b/compiler/rustc_metadata/src/rmeta/encoder.rs
index d42c8b947a4..a7e7e9985f4 100644
--- a/compiler/rustc_metadata/src/rmeta/encoder.rs
+++ b/compiler/rustc_metadata/src/rmeta/encoder.rs
@@ -1981,7 +1981,7 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
                 def_key.disambiguated_data.data = DefPathData::MacroNs(name);
 
                 let def_id = id.to_def_id();
-                self.tables.def_kind.set_some(def_id.index, DefKind::Macro(macro_kind));
+                self.tables.def_kind.set_some(def_id.index, DefKind::Macro(macro_kind.into()));
                 self.tables.proc_macro.set_some(def_id.index, macro_kind);
                 self.encode_attrs(id);
                 record!(self.tables.def_keys[def_id] <- def_key);
diff --git a/compiler/rustc_metadata/src/rmeta/mod.rs b/compiler/rustc_metadata/src/rmeta/mod.rs
index 99174e4ad2f..1f7d142d330 100644
--- a/compiler/rustc_metadata/src/rmeta/mod.rs
+++ b/compiler/rustc_metadata/src/rmeta/mod.rs
@@ -11,7 +11,7 @@ use rustc_abi::{FieldIdx, ReprOptions, VariantIdx};
 use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::svh::Svh;
 use rustc_hir::attrs::StrippedCfgItem;
-use rustc_hir::def::{CtorKind, DefKind, DocLinkResMap};
+use rustc_hir::def::{CtorKind, DefKind, DocLinkResMap, MacroKinds};
 use rustc_hir::def_id::{CrateNum, DefId, DefIdMap, DefIndex, DefPathHash, StableCrateId};
 use rustc_hir::definitions::DefKey;
 use rustc_hir::lang_items::LangItem;
diff --git a/compiler/rustc_metadata/src/rmeta/table.rs b/compiler/rustc_metadata/src/rmeta/table.rs
index 0671aa20399..2cb07a28a8a 100644
--- a/compiler/rustc_metadata/src/rmeta/table.rs
+++ b/compiler/rustc_metadata/src/rmeta/table.rs
@@ -81,7 +81,7 @@ impl FixedSizeEncoding for u64 {
 }
 
 macro_rules! fixed_size_enum {
-    ($ty:ty { $(($($pat:tt)*))* }) => {
+    ($ty:ty { $(($($pat:tt)*))* } $( unreachable { $(($($upat:tt)*))+ } )?) => {
         impl FixedSizeEncoding for Option<$ty> {
             type ByteArray = [u8;1];
 
@@ -103,12 +103,24 @@ macro_rules! fixed_size_enum {
                 b[0] = match self {
                     None => unreachable!(),
                     $(Some($($pat)*) => 1 + ${index()},)*
+                    $(Some($($($upat)*)|+) => unreachable!(),)?
                 }
             }
         }
     }
 }
 
+// Workaround; need const traits to construct bitflags in a const
+macro_rules! const_macro_kinds {
+    ($($name:ident),+$(,)?) => (MacroKinds::from_bits_truncate($(MacroKinds::$name.bits())|+))
+}
+const MACRO_KINDS_ATTR_BANG: MacroKinds = const_macro_kinds!(ATTR, BANG);
+const MACRO_KINDS_DERIVE_BANG: MacroKinds = const_macro_kinds!(DERIVE, BANG);
+const MACRO_KINDS_DERIVE_ATTR: MacroKinds = const_macro_kinds!(DERIVE, ATTR);
+const MACRO_KINDS_DERIVE_ATTR_BANG: MacroKinds = const_macro_kinds!(DERIVE, ATTR, BANG);
+// Ensure that we get a compilation error if MacroKinds gets extended without updating metadata.
+const _: () = assert!(MACRO_KINDS_DERIVE_ATTR_BANG.is_all());
+
 fixed_size_enum! {
     DefKind {
         ( Mod                                      )
@@ -151,10 +163,16 @@ fixed_size_enum! {
         ( Ctor(CtorOf::Struct, CtorKind::Const)    )
         ( Ctor(CtorOf::Variant, CtorKind::Fn)      )
         ( Ctor(CtorOf::Variant, CtorKind::Const)   )
-        ( Macro(MacroKind::Bang)                   )
-        ( Macro(MacroKind::Attr)                   )
-        ( Macro(MacroKind::Derive)                 )
+        ( Macro(MacroKinds::BANG)                  )
+        ( Macro(MacroKinds::ATTR)                  )
+        ( Macro(MacroKinds::DERIVE)                )
+        ( Macro(MACRO_KINDS_ATTR_BANG)             )
+        ( Macro(MACRO_KINDS_DERIVE_ATTR)           )
+        ( Macro(MACRO_KINDS_DERIVE_BANG)           )
+        ( Macro(MACRO_KINDS_DERIVE_ATTR_BANG)      )
         ( SyntheticCoroutineBody                   )
+    } unreachable {
+        ( Macro(_)                                 )
     }
 }