static_assert: make use of anonymous constants

Author: RalfJung

src/librustc_data_structures/macros.rs

@@ -1,13 +1,13 @@
 /// A simple static assertion macro. The first argument should be a unique
 /// ALL_CAPS identifier that describes the condition.
 #[macro_export]
-#[allow_internal_unstable(type_ascription)]
+#[allow_internal_unstable(type_ascription, underscore_const_names)]
 macro_rules! static_assert {
-    ($name:ident: $test:expr) => {
+    ($test:expr) => {
         // Use the bool to access an array such that if the bool is false, the access
         // is out-of-bounds.
         #[allow(dead_code)]
-        static $name: () = [()][!($test: bool) as usize];
+        const _: () = [()][!($test: bool) as usize];
     }
 }
 

src/librustc_mir/transform/qualify_consts.rs

@@ -544,14 +544,14 @@ impl Qualif for IsNotImplicitlyPromotable {
 // Ensure the `IDX` values are sequential (`0..QUALIF_COUNT`).
 macro_rules! static_assert_seq_qualifs {
     ($i:expr => $first:ident $(, $rest:ident)*) => {
-        static_assert!(SEQ_QUALIFS: {
+        static_assert!({
             static_assert_seq_qualifs!($i + 1 => $($rest),*);
 
             $first::IDX == $i
         });
     };
     ($i:expr =>) => {
-        static_assert!(SEQ_QUALIFS: QUALIF_COUNT == $i);
+        static_assert!(QUALIF_COUNT == $i);
     };
 }
 static_assert_seq_qualifs!(