[RFC 2011] Minimal initial implementation

compiler/rustc_span/src/symbol.rs

@@ -157,6 +157,7 @@ symbols! {
         C,
         CStr,
         CString,
+        Capture,
         Center,
         Clone,
         Continue,
@@ -267,6 +268,8 @@ symbols! {
         ToOwned,
         ToString,
         Try,
+        TryCaptureGeneric,
+        TryCapturePrintable,
         TryFrom,
         TryInto,
         Ty,
@@ -276,6 +279,7 @@ symbols! {
         UnsafeArg,
         Vec,
         VecDeque,
+        Wrapper,
         Yield,
         _DECLS,
         _Self,
@@ -358,6 +362,7 @@ symbols! {
         assert_receiver_is_total_eq,
         assert_uninit_valid,
         assert_zero_valid,
+        asserting,
         associated_const_equality,
         associated_consts,
         associated_type_bounds,
@@ -1437,6 +1442,7 @@ symbols! {
         truncf32,
         truncf64,
         try_blocks,
+        try_capture,
         try_from,
         try_into,
         try_trait_v2,
@@ -1499,6 +1505,7 @@ symbols! {
         unsized_tuple_coercion,
         unstable,
         untagged_unions,
+        unused_imports,
         unused_qualifications,
         unwind,
         unwind_attributes,