Rollup merge of #145153 - joshtriplett:macro-kinds-plural, r=petrochenkov

Handle macros with multiple kinds, and improve errors

(I recommend reviewing this commit-by-commit.)

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.

This allows detecting and report macro kind mismatches early, and more precisely, improving various error messages. In particular, this eliminates the case in `failed_to_match_macro` to check for a function-like invocation of a macro with no function-like rules.

Instead, macro kind mismatches now result in an unresolved macro, and we detect this case in `unresolved_macro_suggestions`, which now carefully distinguishes between a kind mismatch and other errors.

This also handles cases of forward-referenced attributes and cyclic attributes.

----

In this PR, I've minimally fixed up `rustdoc` so that it compiles and passes tests. This is just the minimal necessary fixes to handle the switch to `MacroKinds`, and it only works for macros that don't actually have multiple kinds. This will panic (with a `todo!`) if it encounters a macro with multiple kinds.

rustdoc needs further fixes to handle macros with multiple kinds, and to handle attributes and derive macros that aren't proc macros. I'd appreciate some help from a rustdoc expert on that.

----

r? ````````@petrochenkov````````

1 files changed, 11 insertions, 3 deletions

diff --git a/src/librustdoc/clean/mod.rs b/src/librustdoc/clean/mod.rs
index 890bfaced6c..4ff94cc6f3b 100644
--- a/src/librustdoc/clean/mod.rs
+++ b/src/librustdoc/clean/mod.rs
@@ -40,7 +40,7 @@ use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexMap, FxIndexSet, In
 use rustc_errors::codes::*;
 use rustc_errors::{FatalError, struct_span_code_err};
 use rustc_hir::attrs::AttributeKind;
-use rustc_hir::def::{CtorKind, DefKind, Res};
+use rustc_hir::def::{CtorKind, DefKind, MacroKinds, Res};
 use rustc_hir::def_id::{DefId, DefIdMap, DefIdSet, LOCAL_CRATE, LocalDefId};
 use rustc_hir::{LangItem, PredicateOrigin, find_attr};
 use rustc_hir_analysis::hir_ty_lowering::FeedConstTy;
@@ -2845,11 +2845,19 @@ fn clean_maybe_renamed_item<'tcx>(
                 generics: clean_generics(generics, cx),
                 fields: variant_data.fields().iter().map(|x| clean_field(x, cx)).collect(),
             }),
-            ItemKind::Macro(_, macro_def, MacroKind::Bang) => MacroItem(Macro {
+            // FIXME: handle attributes and derives that aren't proc macros, and macros with
+            // multiple kinds
+            ItemKind::Macro(_, macro_def, MacroKinds::BANG) => MacroItem(Macro {
                 source: display_macro_source(cx, name, macro_def),
                 macro_rules: macro_def.macro_rules,
             }),
-            ItemKind::Macro(_, _, macro_kind) => clean_proc_macro(item, &mut name, macro_kind, cx),
+            ItemKind::Macro(_, _, MacroKinds::ATTR) => {
+                clean_proc_macro(item, &mut name, MacroKind::Attr, cx)
+            }
+            ItemKind::Macro(_, _, MacroKinds::DERIVE) => {
+                clean_proc_macro(item, &mut name, MacroKind::Derive, cx)
+            }
+            ItemKind::Macro(_, _, _) => todo!("Handle macros with multiple kinds"),
             // proc macros can have a name set by attributes
             ItemKind::Fn { ref sig, generics, body: body_id, .. } => {
                 clean_fn_or_proc_macro(item, sig, generics, body_id, &mut name, cx)