Split declare_features!.

It's a macro with four clauses, three of which are doing one thing, and
the fourth is doing something completely different. This commit splits
it into two macros, which is more sensible.

Author: nnethercote

compiler/rustc_feature/src/active.rs

@@ -14,16 +14,19 @@ enum FeatureStatus {
     Internal,
 }
 
-macro_rules! declare_features {
-    (__status_to_enum active) => {
+macro_rules! status_to_enum {
+    (active) => {
         FeatureStatus::Default
     };
-    (__status_to_enum incomplete) => {
+    (incomplete) => {
         FeatureStatus::Incomplete
     };
-    (__status_to_enum internal) => {
+    (internal) => {
         FeatureStatus::Internal
     };
+}
+
+macro_rules! declare_features {
     ($(
         $(#[doc = $doc:tt])* ($status:ident, $feature:ident, $ver:expr, $issue:expr, $edition:expr),
     )+) => {
@@ -92,7 +95,7 @@ macro_rules! declare_features {
             pub fn incomplete(&self, feature: Symbol) -> bool {
                 match feature {
                     $(
-                        sym::$feature => declare_features!(__status_to_enum $status) == FeatureStatus::Incomplete,
+                        sym::$feature => status_to_enum!($status) == FeatureStatus::Incomplete,
                     )*
                     // accepted and removed features aren't in this file but are never incomplete
                     _ if self.declared_lang_features.iter().any(|f| f.0 == feature) => false,
@@ -107,7 +110,7 @@ macro_rules! declare_features {
             pub fn internal(&self, feature: Symbol) -> bool {
                 match feature {
                     $(
-                        sym::$feature => declare_features!(__status_to_enum $status) == FeatureStatus::Internal,
+                        sym::$feature => status_to_enum!($status) == FeatureStatus::Internal,
                     )*
                     // accepted and removed features aren't in this file but are never internal
                     // (a removed feature might have been internal, but it doesn't matter anymore)