Gate checking rustc attrs on the feature.

Author: cjgillot

compiler/rustc_hir_typeck/src/callee.rs

@@ -511,7 +511,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 // Untranslatable diagnostics are okay for rustc internals
                 #[allow(rustc::untranslatable_diagnostic)]
                 #[allow(rustc::diagnostic_outside_of_impl)]
-                if self.tcx.has_attr(def_id, sym::rustc_evaluate_where_clauses) {
+                if self.has_rustc_attrs
+                    && self.tcx.has_attr(def_id, sym::rustc_evaluate_where_clauses)
+                {
                     let predicates = self.tcx.predicates_of(def_id);
                     let predicates = predicates.instantiate(self.tcx, args);
                     for (predicate, predicate_span) in predicates {
@@ -894,7 +896,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         }
 
         // If we have `rustc_do_not_const_check`, do not check `[const]` bounds.
-        if self.tcx.has_attr(self.body_id, sym::rustc_do_not_const_check) {
+        if self.has_rustc_attrs && self.tcx.has_attr(self.body_id, sym::rustc_do_not_const_check) {
             return;
         }
 

compiler/rustc_hir_typeck/src/fn_ctxt/mod.rs

@@ -126,6 +126,10 @@ pub(crate) struct FnCtxt<'a, 'tcx> {
     /// These are stored here so we may collect them when canonicalizing user
     /// type ascriptions later.
     pub(super) trait_ascriptions: RefCell<ItemLocalMap<Vec<ty::Clause<'tcx>>>>,
+
+    /// Whether the current crate enables the `rustc_attrs` feature.
+    /// This allows to skip processing attributes in many places.
+    pub(super) has_rustc_attrs: bool,
 }
 
 impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
@@ -154,6 +158,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             diverging_fallback_behavior,
             diverging_block_behavior,
             trait_ascriptions: Default::default(),
+            has_rustc_attrs: root_ctxt.tcx.features().rustc_attrs(),
         }
     }
 
@@ -525,10 +530,13 @@ fn parse_never_type_options_attr(
     let mut fallback = None;
     let mut block = None;
 
-    let items = tcx
-        .get_attr(CRATE_DEF_ID, sym::rustc_never_type_options)
-        .map(|attr| attr.meta_item_list().unwrap())
-        .unwrap_or_default();
+    let items = if tcx.features().rustc_attrs() {
+        tcx.get_attr(CRATE_DEF_ID, sym::rustc_never_type_options)
+            .map(|attr| attr.meta_item_list().unwrap())
+    } else {
+        None
+    };
+    let items = items.unwrap_or_default();
 
     for item in items {
         if item.has_name(sym::fallback) && fallback.is_none() {

compiler/rustc_hir_typeck/src/upvar.rs

@@ -1747,7 +1747,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
     }
 
     fn should_log_capture_analysis(&self, closure_def_id: LocalDefId) -> bool {
-        self.tcx.has_attr(closure_def_id, sym::rustc_capture_analysis)
+        self.has_rustc_attrs && self.tcx.has_attr(closure_def_id, sym::rustc_capture_analysis)
     }
 
     fn log_capture_analysis_first_pass(

compiler/rustc_hir_typeck/src/writeback.rs

@@ -45,7 +45,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
 
         // This attribute causes us to dump some writeback information
         // in the form of errors, which is used for unit tests.
-        let rustc_dump_user_args = self.tcx.has_attr(item_def_id, sym::rustc_dump_user_args);
+        let rustc_dump_user_args =
+            self.has_rustc_attrs && self.tcx.has_attr(item_def_id, sym::rustc_dump_user_args);
 
         let mut wbcx = WritebackCx::new(self, body, rustc_dump_user_args);
         for param in body.params {