Do not visit attributes in `ItemLowerer`.

By default, AST visitors visit expressions that appear in key-value attributes.
Those expressions should not be lowered to HIR, as they do not correspond to actually compiled code.

Since an attribute cannot produce meaningful HIR, just skip them altogether.

3 files changed, 40 insertions, 0 deletions

diff --git a/compiler/rustc_ast_lowering/src/item.rs b/compiler/rustc_ast_lowering/src/item.rs
index 6a4571cf6d2..692f3936824 100644
--- a/compiler/rustc_ast_lowering/src/item.rs
+++ b/compiler/rustc_ast_lowering/src/item.rs
@@ -40,6 +40,11 @@ impl ItemLowerer<'_, '_, '_> {
 }
 
 impl<'a> Visitor<'a> for ItemLowerer<'a, '_, '_> {
+    fn visit_attribute(&mut self, _: &'a Attribute) {
+        // We do not want to lower expressions that appear in attributes,
+        // as they are not accessible to the rest of the HIR.
+    }
+
     fn visit_item(&mut self, item: &'a Item) {
         let hir_id = self.lctx.with_hir_id_owner(item.id, |lctx| {
             let node = lctx.without_in_scope_lifetime_defs(|lctx| lctx.lower_item(item));
diff --git a/src/test/ui/attributes/issue-90873.rs b/src/test/ui/attributes/issue-90873.rs
new file mode 100644
index 00000000000..79ec59e4dc0
--- /dev/null
+++ b/src/test/ui/attributes/issue-90873.rs
@@ -0,0 +1,5 @@
+#![u=||{static d=||1;}]
+//~^ unexpected token
+//~| cannot find attribute `u` in this scope
+//~| `main` function not found in crate `issue_90873`
+//~| missing type for `static` item
diff --git a/src/test/ui/attributes/issue-90873.stderr b/src/test/ui/attributes/issue-90873.stderr
new file mode 100644
index 00000000000..b249be8d0e2
--- /dev/null
+++ b/src/test/ui/attributes/issue-90873.stderr
@@ -0,0 +1,30 @@
+error: unexpected token: `||
+           {
+               static d: _ = || 1;
+           }`
+  --> $DIR/issue-90873.rs:1:6
+   |
+LL | #![u=||{static d=||1;}]
+   |      ^^^^^^^^^^^^^^^^^
+
+error: cannot find attribute `u` in this scope
+  --> $DIR/issue-90873.rs:1:4
+   |
+LL | #![u=||{static d=||1;}]
+   |    ^
+
+error[E0601]: `main` function not found in crate `issue_90873`
+  --> $DIR/issue-90873.rs:1:1
+   |
+LL | #![u=||{static d=||1;}]
+   | ^^^^^^^^^^^^^^^^^^^^^^^ consider adding a `main` function to `$DIR/issue-90873.rs`
+
+error: missing type for `static` item
+  --> $DIR/issue-90873.rs:1:16
+   |
+LL | #![u=||{static d=||1;}]
+   |                ^ help: provide a type for the item: `d: <type>`
+
+error: aborting due to 4 previous errors
+
+For more information about this error, try `rustc --explain E0601`.