Detect and report macro kind mismatches early, and more precisely

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.

Expand test coverage to include all of these cases.

Author: joshtriplett

compiler/rustc_expand/src/mbe/diagnostics.rs

@@ -58,18 +58,6 @@ pub(super) fn failed_to_match_macro(
 
     let Some(BestFailure { token, msg: label, remaining_matcher, .. }) = tracker.best_failure
     else {
-        // FIXME: we should report this at macro resolution time, as we do for
-        // `resolve_macro_cannot_use_as_attr`. We can do that once we track multiple macro kinds for a
-        // Def.
-        if attr_args.is_none() && !rules.iter().any(|rule| matches!(rule, MacroRule::Func { .. })) {
-            let msg = format!("macro has no rules for function-like invocation `{name}!`");
-            let mut err = psess.dcx().struct_span_err(sp, msg);
-            if !def_head_span.is_dummy() {
-                let msg = "this macro has no rules for function-like invocation";
-                err.span_label(def_head_span, msg);
-            }
-            return (sp, err.emit());
-        }
         return (sp, psess.dcx().span_delayed_bug(sp, "failed to match a macro"));
     };
 

compiler/rustc_resolve/messages.ftl

@@ -242,6 +242,9 @@ resolve_lowercase_self =
     attempt to use a non-constant value in a constant
     .suggestion = try using `Self`
 
+resolve_macro_cannot_use_as_fn_like =
+    `{$ident}` exists, but has no rules for function-like invocation
+
 resolve_macro_cannot_use_as_attr =
     `{$ident}` exists, but has no `attr` rules
 

compiler/rustc_resolve/src/diagnostics.rs

@@ -1556,11 +1556,11 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
         if let Some((def_id, unused_ident)) = unused_macro {
             let scope = self.local_macro_def_scopes[&def_id];
             let parent_nearest = parent_scope.module.nearest_parent_mod();
-            if Some(parent_nearest) == scope.opt_def_id() {
+            let unused_macro_kinds = self.local_macro_map[def_id].ext.macro_kinds();
+            if !unused_macro_kinds.contains(macro_kind.into()) {
                 match macro_kind {
                     MacroKind::Bang => {
-                        err.subdiagnostic(MacroDefinedLater { span: unused_ident.span });
-                        err.subdiagnostic(MacroSuggMovePosition { span: ident.span, ident });
+                        err.subdiagnostic(MacroRulesNot::Func { span: unused_ident.span, ident });
                     }
                     MacroKind::Attr => {
                         err.subdiagnostic(MacroRulesNot::Attr { span: unused_ident.span, ident });
@@ -1569,14 +1569,13 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                         err.subdiagnostic(MacroRulesNot::Derive { span: unused_ident.span, ident });
                     }
                 }
-
                 return;
             }
-        }
-
-        if self.macro_names.contains(&ident.normalize_to_macros_2_0()) {
-            err.subdiagnostic(AddedMacroUse);
-            return;
+            if Some(parent_nearest) == scope.opt_def_id() {
+                err.subdiagnostic(MacroDefinedLater { span: unused_ident.span });
+                err.subdiagnostic(MacroSuggMovePosition { span: ident.span, ident });
+                return;
+            }
         }
 
         if ident.name == kw::Default
@@ -1652,6 +1651,11 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
             err.subdiagnostic(note);
             return;
         }
+
+        if self.macro_names.contains(&ident.normalize_to_macros_2_0()) {
+            err.subdiagnostic(AddedMacroUse);
+            return;
+        }
     }
 
     /// Given an attribute macro that failed to be resolved, look for `derive` macros that could

compiler/rustc_resolve/src/errors.rs

@@ -672,6 +672,12 @@ pub(crate) struct MacroSuggMovePosition {
 
 #[derive(Subdiagnostic)]
 pub(crate) enum MacroRulesNot {
+    #[label(resolve_macro_cannot_use_as_fn_like)]
+    Func {
+        #[primary_span]
+        span: Span,
+        ident: Ident,
+    },
     #[label(resolve_macro_cannot_use_as_attr)]
     Attr {
         #[primary_span]

tests/ui/macros/macro-rules-attr-error.rs

@@ -7,9 +7,46 @@ macro_rules! local_attr {
     //~^^ ERROR: local_attr
 }
 
+//~v NOTE: `fn_only` exists, but has no `attr` rules
+macro_rules! fn_only {
+    {} => {}
+}
+
+//~v NOTE: `attr_only` exists, but has no rules for function-like invocation
+macro_rules! attr_only {
+    attr() {} => {}
+}
+
 fn main() {
+    //~v NOTE: in this expansion of #[local_attr]
     #[local_attr]
     struct S;
 
-    local_attr!(arg); //~ ERROR: macro has no rules for function-like invocation
+    //~vv ERROR: cannot find macro `local_attr` in this scope
+    //~| NOTE: `local_attr` is in scope, but it is an attribute
+    local_attr!(arg);
+
+    //~v ERROR: cannot find attribute `fn_only` in this scope
+    #[fn_only]
+    struct S;
+
+    attr_only!(); //~ ERROR: cannot find macro `attr_only` in this scope
+}
+
+//~vv ERROR: cannot find attribute `forward_referenced_attr` in this scope
+//~| NOTE: consider moving the definition of `forward_referenced_attr` before this call
+#[forward_referenced_attr]
+struct S;
+
+//~v NOTE: a macro with the same name exists, but it appears later
+macro_rules! forward_referenced_attr {
+    attr() {} => {}
+}
+
+//~vv ERROR: cannot find attribute `cyclic_attr` in this scope
+//~| NOTE: consider moving the definition of `cyclic_attr` before this call
+#[cyclic_attr]
+//~v NOTE: a macro with the same name exists, but it appears later
+macro_rules! cyclic_attr {
+    attr() {} => {}
 }

tests/ui/macros/macro-rules-attr-error.stderr

@@ -9,14 +9,55 @@ LL |     #[local_attr]
    |
    = note: this error originates in the attribute macro `local_attr` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error: macro has no rules for function-like invocation `local_attr!`
-  --> $DIR/macro-rules-attr-error.rs:14:5
+error: cannot find macro `local_attr` in this scope
+  --> $DIR/macro-rules-attr-error.rs:27:5
    |
-LL | macro_rules! local_attr {
-   | ----------------------- this macro has no rules for function-like invocation
-...
 LL |     local_attr!(arg);
-   |     ^^^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^
+   |
+   = note: `local_attr` is in scope, but it is an attribute: `#[local_attr]`
+
+error: cannot find attribute `fn_only` in this scope
+  --> $DIR/macro-rules-attr-error.rs:30:7
+   |
+LL | macro_rules! fn_only {
+   |              ------- `fn_only` exists, but has no `attr` rules
+...
+LL |     #[fn_only]
+   |       ^^^^^^^
+
+error: cannot find macro `attr_only` in this scope
+  --> $DIR/macro-rules-attr-error.rs:33:5
+   |
+LL | macro_rules! attr_only {
+   |              --------- `attr_only` exists, but has no rules for function-like invocation
+...
+LL |     attr_only!();
+   |     ^^^^^^^^^
+
+error: cannot find attribute `forward_referenced_attr` in this scope
+  --> $DIR/macro-rules-attr-error.rs:38:3
+   |
+LL | #[forward_referenced_attr]
+   |   ^^^^^^^^^^^^^^^^^^^^^^^ consider moving the definition of `forward_referenced_attr` before this call
+   |
+note: a macro with the same name exists, but it appears later
+  --> $DIR/macro-rules-attr-error.rs:42:14
+   |
+LL | macro_rules! forward_referenced_attr {
+   |              ^^^^^^^^^^^^^^^^^^^^^^^
+
+error: cannot find attribute `cyclic_attr` in this scope
+  --> $DIR/macro-rules-attr-error.rs:48:3
+   |
+LL | #[cyclic_attr]
+   |   ^^^^^^^^^^^ consider moving the definition of `cyclic_attr` before this call
+   |
+note: a macro with the same name exists, but it appears later
+  --> $DIR/macro-rules-attr-error.rs:50:14
+   |
+LL | macro_rules! cyclic_attr {
+   |              ^^^^^^^^^^^
 
-error: aborting due to 2 previous errors
+error: aborting due to 6 previous errors