2 files changed, 7 insertions, 23 deletions
diff --git a/compiler/rustc_middle/src/lib.rs b/compiler/rustc_middle/src/lib.rs
index 76a8367b2c4..e9172e767e0 100644
--- a/compiler/rustc_middle/src/lib.rs
+++ b/compiler/rustc_middle/src/lib.rs
@@ -60,6 +60,7 @@
 #![feature(const_option)]
 #![feature(trait_alias)]
 #![feature(ptr_alignment_type)]
+#![feature(macro_metavar_expr)]
 #![recursion_limit = "512"]
 #![allow(rustc::potential_query_instability)]
 
diff --git a/compiler/rustc_middle/src/ty/mod.rs b/compiler/rustc_middle/src/ty/mod.rs
index 17647d13f99..7855749e586 100644
--- a/compiler/rustc_middle/src/ty/mod.rs
+++ b/compiler/rustc_middle/src/ty/mod.rs
@@ -1497,29 +1497,12 @@ struct ParamTag {
     constness: hir::Constness,
 }
 
-unsafe impl rustc_data_structures::tagged_ptr::Tag for ParamTag {
-    const BITS: u32 = 2;
-
-    #[inline]
-    fn into_usize(self) -> usize {
-        match self {
-            Self { reveal: traits::Reveal::UserFacing, constness: hir::Constness::NotConst } => 0,
-            Self { reveal: traits::Reveal::All, constness: hir::Constness::NotConst } => 1,
-            Self { reveal: traits::Reveal::UserFacing, constness: hir::Constness::Const } => 2,
-            Self { reveal: traits::Reveal::All, constness: hir::Constness::Const } => 3,
-        }
-    }
-
-    #[inline]
-    unsafe fn from_usize(ptr: usize) -> Self {
-        match ptr {
-            0 => Self { reveal: traits::Reveal::UserFacing, constness: hir::Constness::NotConst },
-            1 => Self { reveal: traits::Reveal::All, constness: hir::Constness::NotConst },
-            2 => Self { reveal: traits::Reveal::UserFacing, constness: hir::Constness::Const },
-            3 => Self { reveal: traits::Reveal::All, constness: hir::Constness::Const },
-            _ => std::hint::unreachable_unchecked(),
-        }
-    }
+impl_tag! {
+    impl Tag for ParamTag;
+    ParamTag { reveal: traits::Reveal::UserFacing, constness: hir::Constness::NotConst },
+    ParamTag { reveal: traits::Reveal::All,        constness: hir::Constness::NotConst },
+    ParamTag { reveal: traits::Reveal::UserFacing, constness: hir::Constness::Const    },
+    ParamTag { reveal: traits::Reveal::All,        constness: hir::Constness::Const    },
 }
 
 impl<'tcx> fmt::Debug for ParamEnv<'tcx> {