Auto merge of #95562 - lcnr:attr-no-encode, r=davidtwco

don't encode only locally used attrs

Part of https://github.com/rust-lang/compiler-team/issues/505.

We now filter builtin attributes before encoding them in the crate metadata in case they should only be used in the local crate. To prevent accidental misuse `get_attrs` now requires the caller to state which attribute they are interested in. For places where that isn't trivially possible, I've added a method `fn get_attrs_unchecked` which I intend to remove in a followup PR.

After this pull request landed, we can then slowly move all attributes to only be used in the local crate while being certain that we don't accidentally try to access them from extern crates.

cc https://github.com/rust-lang/rust/pull/94963#issuecomment-1082924289

3 files changed, 13 insertions, 17 deletions

diff --git a/compiler/rustc_const_eval/src/transform/check_consts/check.rs b/compiler/rustc_const_eval/src/transform/check_consts/check.rs
index 7e2a50444db..8d3bbefb371 100644
--- a/compiler/rustc_const_eval/src/transform/check_consts/check.rs
+++ b/compiler/rustc_const_eval/src/transform/check_consts/check.rs
@@ -312,11 +312,7 @@ impl<'mir, 'tcx> Checker<'mir, 'tcx> {
 
             Status::Unstable(gate) if self.tcx.features().enabled(gate) => {
                 let unstable_in_stable = self.ccx.is_const_stable_const_fn()
-                    && !super::rustc_allow_const_fn_unstable(
-                        self.tcx,
-                        self.def_id().to_def_id(),
-                        gate,
-                    );
+                    && !super::rustc_allow_const_fn_unstable(self.tcx, self.def_id(), gate);
                 if unstable_in_stable {
                     emit_unstable_in_stable_error(self.ccx, span, gate);
                 }
@@ -713,7 +709,7 @@ impl<'tcx> Visitor<'tcx> for Checker<'_, 'tcx> {
         match &terminator.kind {
             TerminatorKind::Call { func, args, fn_span, from_hir_call, .. } => {
                 let ConstCx { tcx, body, param_env, .. } = *self.ccx;
-                let caller = self.def_id().to_def_id();
+                let caller = self.def_id();
 
                 let fn_ty = func.ty(body, tcx);
 
@@ -797,7 +793,7 @@ impl<'tcx> Visitor<'tcx> for Checker<'_, 'tcx> {
                             // trait.
                             let callee_trait = tcx.trait_of_item(callee);
                             if callee_trait.is_some()
-                                && tcx.has_attr(caller, sym::default_method_body_is_const)
+                                && tcx.has_attr(caller.to_def_id(), sym::default_method_body_is_const)
                                 && callee_trait == tcx.trait_of_item(caller)
                                 // Can only call methods when it's `<Self as TheTrait>::f`.
                                 && tcx.types.self_param == substs.type_at(0)
diff --git a/compiler/rustc_const_eval/src/transform/check_consts/mod.rs b/compiler/rustc_const_eval/src/transform/check_consts/mod.rs
index 25ba97ee605..23e2afae791 100644
--- a/compiler/rustc_const_eval/src/transform/check_consts/mod.rs
+++ b/compiler/rustc_const_eval/src/transform/check_consts/mod.rs
@@ -66,8 +66,12 @@ impl<'mir, 'tcx> ConstCx<'mir, 'tcx> {
     }
 }
 
-pub fn rustc_allow_const_fn_unstable(tcx: TyCtxt<'_>, def_id: DefId, feature_gate: Symbol) -> bool {
-    let attrs = tcx.get_attrs(def_id);
+pub fn rustc_allow_const_fn_unstable(
+    tcx: TyCtxt<'_>,
+    def_id: LocalDefId,
+    feature_gate: Symbol,
+) -> bool {
+    let attrs = tcx.hir().attrs(tcx.hir().local_def_id_to_hir_id(def_id));
     attr::rustc_allow_const_fn_unstable(&tcx.sess, attrs).any(|name| name == feature_gate)
 }
 
diff --git a/compiler/rustc_const_eval/src/transform/check_consts/ops.rs b/compiler/rustc_const_eval/src/transform/check_consts/ops.rs
index ba248a3b6cb..122471b208d 100644
--- a/compiler/rustc_const_eval/src/transform/check_consts/ops.rs
+++ b/compiler/rustc_const_eval/src/transform/check_consts/ops.rs
@@ -1,5 +1,6 @@
 //! Concrete error types for all operations which may be invalid in a certain const context.
 
+use hir::def_id::LocalDefId;
 use rustc_errors::{struct_span_err, Applicability, DiagnosticBuilder, ErrorGuaranteed};
 use rustc_hir as hir;
 use rustc_hir::def_id::DefId;
@@ -95,7 +96,7 @@ impl<'tcx> NonConstOp<'tcx> for FnCallIndirect {
 /// A function call where the callee is not marked as `const`.
 #[derive(Debug, Clone, Copy)]
 pub struct FnCallNonConst<'tcx> {
-    pub caller: DefId,
+    pub caller: LocalDefId,
     pub callee: DefId,
     pub substs: SubstsRef<'tcx>,
     pub span: Span,
@@ -117,13 +118,8 @@ impl<'tcx> NonConstOp<'tcx> for FnCallNonConst<'tcx> {
             match self_ty.kind() {
                 Param(param_ty) => {
                     debug!(?param_ty);
-                    if let Some(generics) = caller
-                        .as_local()
-                        .map(|id| tcx.hir().local_def_id_to_hir_id(id))
-                        .map(|id| tcx.hir().get(id))
-                        .as_ref()
-                        .and_then(|node| node.generics())
-                    {
+                    let caller_hir_id = tcx.hir().local_def_id_to_hir_id(caller);
+                    if let Some(generics) = tcx.hir().get(caller_hir_id).generics() {
                         let constraint = with_no_trimmed_paths!(format!(
                             "~const {}",
                             trait_ref.print_only_trait_path()