Remove `#[default..]` and add `#[const_trait]`

4 files changed, 12 insertions, 12 deletions

diff --git a/compiler/rustc_const_eval/src/const_eval/machine.rs b/compiler/rustc_const_eval/src/const_eval/machine.rs
index 9de5541bfe3..8bd8280497c 100644
--- a/compiler/rustc_const_eval/src/const_eval/machine.rs
+++ b/compiler/rustc_const_eval/src/const_eval/machine.rs
@@ -277,8 +277,9 @@ impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for CompileTimeInterpreter<'mir,
             // sensitive check here.  But we can at least rule out functions that are not const
             // at all.
             if !ecx.tcx.is_const_fn_raw(def.did) {
-                // allow calling functions marked with #[default_method_body_is_const].
-                if !ecx.tcx.has_attr(def.did, sym::default_method_body_is_const) {
+                // allow calling functions inside a trait marked with #[const_trait].
+                if !matches!(ecx.tcx.trait_of_item(def.did), Some(trait_id) if ecx.tcx.has_attr(trait_id, sym::const_trait))
+                {
                     // We certainly do *not* want to actually call the fn
                     // though, so be sure we return here.
                     throw_unsup_format!("calling non-const function `{}`", instance)
diff --git a/compiler/rustc_const_eval/src/lib.rs b/compiler/rustc_const_eval/src/lib.rs
index eacb5978d99..d2b5ef8ea6f 100644
--- a/compiler/rustc_const_eval/src/lib.rs
+++ b/compiler/rustc_const_eval/src/lib.rs
@@ -9,6 +9,7 @@ Rust MIR: a lowered representation of Rust.
 #![feature(control_flow_enum)]
 #![feature(decl_macro)]
 #![feature(exact_size_is_empty)]
+#![feature(let_chains)]
 #![feature(let_else)]
 #![feature(map_try_insert)]
 #![feature(min_specialization)]
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 2c669dd6d9a..57c073cca4d 100644
--- a/compiler/rustc_const_eval/src/transform/check_consts/check.rs
+++ b/compiler/rustc_const_eval/src/transform/check_consts/check.rs
@@ -774,13 +774,11 @@ impl<'tcx> Visitor<'tcx> for Checker<'_, 'tcx> {
                             }
                         }
                         _ if !tcx.is_const_fn_raw(callee) => {
-                            // At this point, it is only legal when the caller is marked with
-                            // #[default_method_body_is_const], and the callee is in the same
-                            // trait.
-                            let callee_trait = tcx.trait_of_item(callee);
-                            if callee_trait.is_some()
-                                && tcx.has_attr(caller.to_def_id(), sym::default_method_body_is_const)
-                                && callee_trait == tcx.trait_of_item(caller)
+                            // At this point, it is only legal when the caller is in a trait
+                            // marked with #[const_trait], and the callee is in the same trait.
+                            if let Some(callee_trait) = tcx.trait_of_item(callee)
+                                && tcx.has_attr(callee_trait, sym::const_trait)
+                                && Some(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)
                             {
@@ -875,7 +873,7 @@ impl<'tcx> Visitor<'tcx> for Checker<'_, 'tcx> {
 
                 if !tcx.is_const_fn_raw(callee) {
                     if tcx.trait_of_item(callee).is_some() {
-                        if tcx.has_attr(callee, sym::default_method_body_is_const) {
+                        if let Some(callee_trait) = tcx.trait_of_item(callee) && tcx.has_attr(callee_trait, sym::const_trait) {
                             // To get to here we must have already found a const impl for the
                             // trait, but for it to still be non-const can be that the impl is
                             // using default method bodies.
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 0f79fe5513d..32cabb1f899 100644
--- a/compiler/rustc_const_eval/src/transform/check_consts/mod.rs
+++ b/compiler/rustc_const_eval/src/transform/check_consts/mod.rs
@@ -84,10 +84,10 @@ pub fn rustc_allow_const_fn_unstable(
 // functions are subject to more stringent restrictions than "const-unstable" functions: They
 // cannot use unstable features and can only call other "const-stable" functions.
 pub fn is_const_stable_const_fn(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
-    // A default body marked const is not const-stable because const
+    // A default body in a `#[const_trait]` is not const-stable because const
     // trait fns currently cannot be const-stable. We shouldn't
     // restrict default bodies to only call const-stable functions.
-    if tcx.has_attr(def_id, sym::default_method_body_is_const) {
+    if let Some(trait_id) = tcx.trait_of_item(def_id) && tcx.has_attr(trait_id, sym::const_trait) {
         return false;
     }