Fix cfg_attr invalidating derive identifier IDE functionality

crates/hir/src/semantics.rs

@@ -364,9 +364,6 @@ impl<'db, DB: HirDatabase> Semantics<'db, DB> {
         self.imp.resolve_derive_ident(derive, ident)
     }
 
-    // FIXME: use this instead?
-    // pub fn resolve_name_ref(&self, name_ref: &ast::NameRef) -> Option<???>;
-
     pub fn record_literal_missing_fields(&self, literal: &ast::RecordExpr) -> Vec<(Field, Type)> {
         self.imp.record_literal_missing_fields(literal)
     }
@@ -931,7 +928,6 @@ impl<'db> SemanticsImpl<'db> {
                 file.with_value(derive.clone()),
             )?;
             let attrs = adt_def.attrs(self.db);
-            // FIXME: https://github.com/rust-analyzer/rust-analyzer/issues/11298
             let mut derive_paths = attrs.get(attr_id)?.parse_path_comma_token_tree()?;
 
             let derive_idx = tt

crates/hir_def/src/attr.rs

@@ -73,8 +73,8 @@ impl ops::Deref for RawAttrs {
     }
 }
 impl Attrs {
-    pub fn get(&self, AttrId { ast_index, .. }: AttrId) -> Option<&Attr> {
-        (**self).get(ast_index as usize)
+    pub fn get(&self, id: AttrId) -> Option<&Attr> {
+        (**self).iter().find(|attr| attr.id == id)
     }
 }
 
@@ -89,14 +89,6 @@ impl ops::Deref for Attrs {
     }
 }
 
-impl ops::Index<AttrId> for Attrs {
-    type Output = Attr;
-
-    fn index(&self, AttrId { ast_index, .. }: AttrId) -> &Self::Output {
-        &(**self)[ast_index as usize]
-    }
-}
-
 impl ops::Deref for AttrsWithOwner {
     type Target = Attrs;
 
@@ -110,7 +102,7 @@ impl RawAttrs {
 
     pub(crate) fn new(db: &dyn DefDatabase, owner: &dyn ast::HasAttrs, hygiene: &Hygiene) -> Self {
         let entries = collect_attrs(owner)
-            .flat_map(|(id, attr)| match attr {
+            .filter_map(|(id, attr)| match attr {
                 Either::Left(attr) => {
                     attr.meta().and_then(|meta| Attr::from_src(db, meta, hygiene, id))
                 }

crates/ide/src/goto_definition.rs

@@ -1364,10 +1364,21 @@ impl Twait for Stwuct {
     fn goto_def_derive_input() {
         check(
             r#"
+        //- minicore:derive
+        #[rustc_builtin_macro]
+        pub macro Copy {}
+               // ^^^^
+        #[derive(Copy$0)]
+        struct Foo;
+                    "#,
+        );
+        check(
+            r#"
 //- minicore:derive
 #[rustc_builtin_macro]
 pub macro Copy {}
        // ^^^^
+#[cfg_attr(feature = "false", derive)]
 #[derive(Copy$0)]
 struct Foo;
             "#,