Diagnostic for using macro_rules macro as attr/derive

Author: clubby789

compiler/rustc_resolve/messages.ftl

@@ -257,8 +257,11 @@ resolve_lowercase_self =
     attempt to use a non-constant value in a constant
     .suggestion = try using `Self`
 
+resolve_macro_cannot_use_as_attr = `macro_rules!` macros cannot be used as attribute macros
+resolve_macro_cannot_use_as_derive = `macro_rules!` macros cannot be used as derive macros
+
 resolve_macro_defined_later =
-    a macro with the same name exists, but it appears later at here
+    a macro with the same name exists, but it appears later
 
 resolve_macro_expanded_extern_crate_cannot_shadow_extern_arguments =
     macro-expanded `extern crate` items cannot shadow names passed with `--extern`
@@ -271,6 +274,12 @@ resolve_macro_extern_deprecated =
     `#[macro_escape]` is a deprecated synonym for `#[macro_use]`
     .help = try an outer attribute: `#[macro_use]`
 
+resolve_macro_not_attr =
+    `{$ident}` exists, but is not an attribute macro
+
+resolve_macro_not_derive =
+    `{$ident}` exists, but is not an derive macro
+
 resolve_macro_use_extern_crate_self = `#[macro_use]` is not supported on `extern crate self`
 
 resolve_macro_use_name_already_in_use =

compiler/rustc_resolve/src/diagnostics.rs

@@ -35,7 +35,8 @@ use tracing::debug;
 
 use crate::errors::{
     self, AddedMacroUse, ChangeImportBinding, ChangeImportBindingSuggestion, ConsiderAddingADerive,
-    ExplicitUnsafeTraits, MacroDefinedLater, MacroSuggMovePosition, MaybeMissingMacroRulesName,
+    ExplicitUnsafeTraits, MacroDefinedLater, MacroRulesNot, MacroSuggMovePosition,
+    MaybeMissingMacroRulesName,
 };
 use crate::imports::{Import, ImportKind};
 use crate::late::{PatternSource, Rib};
@@ -1475,8 +1476,19 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
             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() {
-                err.subdiagnostic(MacroDefinedLater { span: unused_ident.span });
-                err.subdiagnostic(MacroSuggMovePosition { span: ident.span, ident });
+                match macro_kind {
+                    MacroKind::Bang => {
+                        err.subdiagnostic(MacroDefinedLater { span: unused_ident.span });
+                        err.subdiagnostic(MacroSuggMovePosition { span: ident.span, ident });
+                    }
+                    MacroKind::Attr => {
+                        err.subdiagnostic(MacroRulesNot::Attr { span: unused_ident.span, ident });
+                    }
+                    MacroKind::Derive => {
+                        err.subdiagnostic(MacroRulesNot::Derive { span: unused_ident.span, ident });
+                    }
+                }
+
                 return;
             }
         }

compiler/rustc_resolve/src/errors.rs

@@ -665,6 +665,24 @@ pub(crate) struct MacroSuggMovePosition {
     pub(crate) ident: Ident,
 }
 
+#[derive(Subdiagnostic)]
+pub(crate) enum MacroRulesNot {
+    #[label(resolve_macro_not_attr)]
+    #[help(resolve_macro_cannot_use_as_attr)]
+    Attr {
+        #[primary_span]
+        span: Span,
+        ident: Ident,
+    },
+    #[label(resolve_macro_not_derive)]
+    #[help(resolve_macro_cannot_use_as_derive)]
+    Derive {
+        #[primary_span]
+        span: Span,
+        ident: Ident,
+    },
+}
+
 #[derive(Subdiagnostic)]
 #[note(resolve_missing_macro_rules_name)]
 pub(crate) struct MaybeMissingMacroRulesName {

tests/ui/macros/defined-later-issue-121061-2.stderr

@@ -4,7 +4,7 @@ error: cannot find macro `something_later` in this scope
 LL |         something_later!();
    |         ^^^^^^^^^^^^^^^ consider moving the definition of `something_later` before this call
    |
-note: a macro with the same name exists, but it appears later at here
+note: a macro with the same name exists, but it appears later
   --> $DIR/defined-later-issue-121061-2.rs:6:18
    |
 LL |     macro_rules! something_later {

tests/ui/macros/defined-later-issue-121061.stderr

@@ -4,7 +4,7 @@ error: cannot find macro `something_later` in this scope
 LL |     something_later!();
    |     ^^^^^^^^^^^^^^^ consider moving the definition of `something_later` before this call
    |
-note: a macro with the same name exists, but it appears later at here
+note: a macro with the same name exists, but it appears later
   --> $DIR/defined-later-issue-121061.rs:5:14
    |
 LL | macro_rules! something_later {

tests/ui/macros/macro-rules-as-derive-or-attr-issue-132928.stderr

@@ -1,10 +1,13 @@
 error: cannot find derive macro `sample` in this scope
   --> $DIR/macro-rules-as-derive-or-attr-issue-132928.rs:6:10
    |
+LL | macro_rules! sample { () => {} }
+   |              ------ `sample` exists, but is not an derive macro
+...
 LL | #[derive(sample)]
-   |          ^^^^^^ consider moving the definition of `sample` before this call
+   |          ^^^^^^
    |
-note: a macro with the same name exists, but it appears later at here
+help: `macro_rules!` macros cannot be used as derive macros
   --> $DIR/macro-rules-as-derive-or-attr-issue-132928.rs:3:14
    |
 LL | macro_rules! sample { () => {} }
@@ -13,10 +16,13 @@ LL | macro_rules! sample { () => {} }
 error: cannot find attribute `sample` in this scope
   --> $DIR/macro-rules-as-derive-or-attr-issue-132928.rs:5:3
    |
+LL | macro_rules! sample { () => {} }
+   |              ------ `sample` exists, but is not an attribute macro
+LL |
 LL | #[sample]
-   |   ^^^^^^ consider moving the definition of `sample` before this call
+   |   ^^^^^^
    |
-note: a macro with the same name exists, but it appears later at here
+help: `macro_rules!` macros cannot be used as attribute macros
   --> $DIR/macro-rules-as-derive-or-attr-issue-132928.rs:3:14
    |
 LL | macro_rules! sample { () => {} }
@@ -25,10 +31,13 @@ LL | macro_rules! sample { () => {} }
 error: cannot find derive macro `sample` in this scope
   --> $DIR/macro-rules-as-derive-or-attr-issue-132928.rs:6:10
    |
+LL | macro_rules! sample { () => {} }
+   |              ------ `sample` exists, but is not an derive macro
+...
 LL | #[derive(sample)]
-   |          ^^^^^^ consider moving the definition of `sample` before this call
+   |          ^^^^^^
    |
-note: a macro with the same name exists, but it appears later at here
+help: `macro_rules!` macros cannot be used as derive macros
   --> $DIR/macro-rules-as-derive-or-attr-issue-132928.rs:3:14
    |
 LL | macro_rules! sample { () => {} }
@@ -38,10 +47,13 @@ LL | macro_rules! sample { () => {} }
 error: cannot find derive macro `sample` in this scope
   --> $DIR/macro-rules-as-derive-or-attr-issue-132928.rs:6:10
    |
+LL | macro_rules! sample { () => {} }
+   |              ------ `sample` exists, but is not an derive macro
+...
 LL | #[derive(sample)]
-   |          ^^^^^^ consider moving the definition of `sample` before this call
+   |          ^^^^^^
    |
-note: a macro with the same name exists, but it appears later at here
+help: `macro_rules!` macros cannot be used as derive macros
   --> $DIR/macro-rules-as-derive-or-attr-issue-132928.rs:3:14
    |
 LL | macro_rules! sample { () => {} }