Actually implement the feature in the compiler

Including all the bootstrapping tweaks in the library.

compiler/rustc_span/src/symbol.rs

@@ -130,10 +130,12 @@ symbols! {
         BTreeSet,
         BinaryHeap,
         Borrow,
+        Break,
         C,
         CString,
         Center,
         Clone,
+        Continue,
         Copy,
         Count,
         Debug,
@@ -326,6 +328,7 @@ symbols! {
         box_patterns,
         box_syntax,
         braced_empty_structs,
+        branch,
         breakpoint,
         bridge,
         bswap,
@@ -410,6 +413,7 @@ symbols! {
         constructor,
         contents,
         context,
+        control_flow_enum,
         convert,
         copy,
         copy_closures,
@@ -510,7 +514,6 @@ symbols! {
         env,
         eq,
         ermsb_target_feature,
-        err,
         exact_div,
         except,
         exchange_malloc,
@@ -580,10 +583,10 @@ symbols! {
         frem_fast,
         from,
         from_desugaring,
-        from_error,
         from_generator,
         from_method,
-        from_ok,
+        from_output,
+        from_residual,
         from_size_align_unchecked,
         from_trait,
         from_usize,
@@ -652,7 +655,6 @@ symbols! {
         instruction_set,
         intel,
         into_iter,
-        into_result,
         into_trait,
         intra_doc_pointers,
         intrinsics,
@@ -962,6 +964,7 @@ symbols! {
         repr_packed,
         repr_simd,
         repr_transparent,
+        residual,
         result,
         result_type,
         rhs,
@@ -1227,7 +1230,7 @@ symbols! {
         try_blocks,
         try_from_trait,
         try_into_trait,
-        try_trait,
+        try_trait_v2,
         tt,
         tuple,
         tuple_from_req,