Point at item following invalid crate-level inner attribute

Author: estebank

compiler/rustc_passes/messages.ftl

@@ -393,6 +393,9 @@ passes_invalid_attr_at_crate_level =
     `{$name}` attribute cannot be used at crate level
     .suggestion = perhaps you meant to use an outer attribute
 
+passes_invalid_attr_at_crate_level_item =
+    the inner attribute doesn't annotate this {$kind}
+
 passes_invalid_deprecation_version =
     invalid deprecation version found
     .label = invalid deprecation version

compiler/rustc_passes/src/check_attr.rs

@@ -2522,6 +2522,15 @@ fn check_invalid_crate_level_attr(tcx: TyCtxt<'_>, attrs: &[Attribute]) {
     ];
 
     for attr in attrs {
+        let item = tcx
+            .hir()
+            .items()
+            .map(|id| tcx.hir().item(id))
+            .find(|item| !item.span.is_dummy()) // Skip prelude `use`s
+            .map(|item| errors::ItemFollowingInnerAttr {
+                span: item.span,
+                kind: item.kind.descr(),
+            });
         // This function should only be called with crate attributes
         // which are inner attributes always but lets check to make sure
         if attr.style == AttrStyle::Inner {
@@ -2531,6 +2540,7 @@ fn check_invalid_crate_level_attr(tcx: TyCtxt<'_>, attrs: &[Attribute]) {
                         span: attr.span,
                         snippet: tcx.sess.source_map().span_to_snippet(attr.span).ok(),
                         name: *attr_to_check,
+                        item,
                     });
                 }
             }

compiler/rustc_passes/src/errors.rs

@@ -851,6 +851,13 @@ pub struct InvalidAttrAtCrateLevel {
     pub span: Span,
     pub snippet: Option<String>,
     pub name: Symbol,
+    pub item: Option<ItemFollowingInnerAttr>,
+}
+
+#[derive(Clone, Copy)]
+pub struct ItemFollowingInnerAttr {
+    pub span: Span,
+    pub kind: &'static str,
 }
 
 impl IntoDiagnostic<'_> for InvalidAttrAtCrateLevel {
@@ -872,6 +879,10 @@ impl IntoDiagnostic<'_> for InvalidAttrAtCrateLevel {
                 rustc_errors::Applicability::MachineApplicable,
             );
         }
+        if let Some(item) = self.item {
+            diag.set_arg("kind", item.kind);
+            diag.span_label(item.span, fluent::passes_invalid_attr_at_crate_level_item);
+        }
         diag
     }
 }

tests/ui/attributes/unix_sigpipe/unix_sigpipe-crate.stderr

@@ -3,6 +3,9 @@ error: `unix_sigpipe` attribute cannot be used at crate level
    |
 LL | #![unix_sigpipe = "inherit"]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+LL |
+LL | fn main() {}
+   | ------------ the inner attribute doesn't annotate this function
    |
 help: perhaps you meant to use an outer attribute
    |

tests/ui/derives/issue-36617.stderr

@@ -43,6 +43,9 @@ error: `derive` attribute cannot be used at crate level
    |
 LL | #![derive(Copy)]
    | ^^^^^^^^^^^^^^^^
+...
+LL | fn main() {}
+   | ------------ the inner attribute doesn't annotate this function
    |
 help: perhaps you meant to use an outer attribute
    |
@@ -55,6 +58,9 @@ error: `test` attribute cannot be used at crate level
    |
 LL | #![test]
    | ^^^^^^^^
+...
+LL | fn main() {}
+   | ------------ the inner attribute doesn't annotate this function
    |
 help: perhaps you meant to use an outer attribute
    |
@@ -67,6 +73,9 @@ error: `test_case` attribute cannot be used at crate level
    |
 LL | #![test_case]
    | ^^^^^^^^^^^^^
+...
+LL | fn main() {}
+   | ------------ the inner attribute doesn't annotate this function
    |
 help: perhaps you meant to use an outer attribute
    |
@@ -79,6 +88,9 @@ error: `bench` attribute cannot be used at crate level
    |
 LL | #![bench]
    | ^^^^^^^^^
+...
+LL | fn main() {}
+   | ------------ the inner attribute doesn't annotate this function
    |
 help: perhaps you meant to use an outer attribute
    |
@@ -91,6 +103,9 @@ error: `global_allocator` attribute cannot be used at crate level
    |
 LL | #![global_allocator]
    | ^^^^^^^^^^^^^^^^^^^^
+...
+LL | fn main() {}
+   | ------------ the inner attribute doesn't annotate this function
    |
 help: perhaps you meant to use an outer attribute
    |

tests/ui/feature-gates/issue-43106-gating-of-bench.stderr

@@ -11,6 +11,9 @@ error: `bench` attribute cannot be used at crate level
    |
 LL | #![bench                   = "4100"]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+...
+LL | fn main() {}
+   | ------------ the inner attribute doesn't annotate this function
    |
 help: perhaps you meant to use an outer attribute
    |

tests/ui/feature-gates/issue-43106-gating-of-builtin-attrs-error.rs

@@ -32,6 +32,12 @@
 //~^ ERROR attribute should be applied to function or closure
 mod inline {
     //~^ NOTE not a function or closure
+    //~| NOTE the inner attribute doesn't annotate this module
+    //~| NOTE the inner attribute doesn't annotate this module
+    //~| NOTE the inner attribute doesn't annotate this module
+    //~| NOTE the inner attribute doesn't annotate this module
+    //~| NOTE the inner attribute doesn't annotate this module
+    //~| NOTE the inner attribute doesn't annotate this module
 
     mod inner { #![inline] }
     //~^ ERROR attribute should be applied to function or closure