Do not visit attributes in ItemLowerer.

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));

compiler/rustc_resolve/src/late.rs

@@ -431,6 +431,10 @@ struct LateResolutionVisitor<'a, 'b, 'ast> {
 
 /// Walks the whole crate in DFS order, visiting each item, resolving names as it goes.
 impl<'a: 'ast, 'ast> Visitor<'ast> for LateResolutionVisitor<'a, '_, 'ast> {
+    fn visit_attribute(&mut self, _: &'ast Attribute) {
+        // We do not want to resolve expressions that appear in attributes,
+        // as they do not correspond to actual code.
+    }
     fn visit_item(&mut self, item: &'ast Item) {
         let prev = replace(&mut self.diagnostic_metadata.current_item, Some(item));
         // Always report errors in items we just entered.

src/test/ui/attributes/issue-90873.rs

@@ -0,0 +1,9 @@
+#![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
+
+#![a={impl std::ops::Neg for i8 {}}]
+//~^ ERROR unexpected token
+//~| ERROR cannot find attribute `a` in this scope

src/test/ui/attributes/issue-90873.stderr

@@ -0,0 +1,50 @@
+error: unexpected token: `||
+           {
+               static d: _ = || 1;
+           }`
+  --> $DIR/issue-90873.rs:1:6
+   |
+LL | #![u=||{static d=||1;}]
+   |      ^^^^^^^^^^^^^^^^^
+
+error: unexpected token: `{
+           impl std::ops::Neg for i8 { }
+       }`
+  --> $DIR/issue-90873.rs:7:6
+   |
+LL | #![a={impl std::ops::Neg for i8 {}}]
+   |      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: cannot find attribute `u` in this scope
+  --> $DIR/issue-90873.rs:1:4
+   |
+LL | #![u=||{static d=||1;}]
+   |    ^
+
+error: cannot find attribute `a` in this scope
+  --> $DIR/issue-90873.rs:7:4
+   |
+LL | #![a={impl std::ops::Neg for i8 {}}]
+   |    ^
+
+error[E0601]: `main` function not found in crate `issue_90873`
+  --> $DIR/issue-90873.rs:1:1
+   |
+LL | / #![u=||{static d=||1;}]
+LL | |
+LL | |
+LL | |
+LL | |
+LL | |
+LL | | #![a={impl std::ops::Neg for i8 {}}]
+   | |____________________________________^ consider adding a `main` function to `$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 6 previous errors
+
+For more information about this error, try `rustc --explain E0601`.

src/test/ui/consts/issue-90878-2.rs

@@ -1,7 +1,5 @@
  #![l=|x|[b;x ]] //~ ERROR unexpected token: `|x| [b; x]`
 //~^ ERROR cannot find attribute `l` in this scope
-//~^^ ERROR attempt to use a non-constant value in a constant [E0435]
-//~^^^ ERROR cannot find value `b` in this scope [E0425]
 
 // notice the space at the start,
 // we can't attach any attributes to this file because it needs to be at the start

src/test/ui/consts/issue-90878-2.stderr

@@ -10,21 +10,5 @@ error: cannot find attribute `l` in this scope
 LL |  #![l=|x|[b;x ]]
    |     ^
 
-error[E0435]: attempt to use a non-constant value in a constant
-  --> $DIR/issue-90878-2.rs:1:13
-   |
-LL |  #![l=|x|[b;x ]]
-   |        -    ^
-   |        |
-   |        this would need to be a `const`
-
-error[E0425]: cannot find value `b` in this scope
-  --> $DIR/issue-90878-2.rs:1:11
-   |
-LL |  #![l=|x|[b;x ]]
-   |           ^ help: a local variable with a similar name exists: `x`
-
-error: aborting due to 4 previous errors
+error: aborting due to 2 previous errors
 
-Some errors have detailed explanations: E0425, E0435.
-For more information about an error, try `rustc --explain E0425`.