Pre-intern a symbol for env!("CFG_RELEASE")

Author: dtolnay

compiler/rustc_attr/src/builtin.rs

@@ -26,10 +26,6 @@ pub const VERSION_PLACEHOLDER: &str = "CURRENT_RUSTC_VERSION";
 
 pub const CURRENT_RUSTC_VERSION: &str = env!("CFG_RELEASE");
 
-pub fn rust_version_symbol() -> Symbol {
-    Symbol::intern(CURRENT_RUSTC_VERSION)
-}
-
 pub fn is_builtin_attr(attr: &Attribute) -> bool {
     attr.is_doc_comment() || attr.ident().is_some_and(|ident| is_builtin_attr_name(ident.name))
 }

compiler/rustc_passes/src/lib_features.rs

@@ -5,7 +5,7 @@
 //! collect them instead.
 
 use rustc_ast::Attribute;
-use rustc_attr::{rust_version_symbol, VERSION_PLACEHOLDER};
+use rustc_attr::VERSION_PLACEHOLDER;
 use rustc_hir::intravisit::Visitor;
 use rustc_middle::hir::nested_filter;
 use rustc_middle::middle::lib_features::LibFeatures;
@@ -59,7 +59,7 @@ impl<'tcx> LibFeatureCollector<'tcx> {
                 if let Some(s) = since
                     && s.as_str() == VERSION_PLACEHOLDER
                 {
-                    since = Some(rust_version_symbol());
+                    since = Some(sym::env_CFG_RELEASE);
                 }
 
                 if let Some(feature) = feature {

compiler/rustc_passes/src/stability.rs

@@ -3,8 +3,8 @@
 
 use crate::errors;
 use rustc_attr::{
-    self as attr, rust_version_symbol, ConstStability, Since, Stability, StabilityLevel, Unstable,
-    UnstableReason, VERSION_PLACEHOLDER,
+    self as attr, ConstStability, Since, Stability, StabilityLevel, Unstable, UnstableReason,
+    VERSION_PLACEHOLDER,
 };
 use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexMap};
 use rustc_hir as hir;
@@ -1115,7 +1115,7 @@ fn unnecessary_stable_feature_lint(
     mut since: Symbol,
 ) {
     if since.as_str() == VERSION_PLACEHOLDER {
-        since = rust_version_symbol();
+        since = sym::env_CFG_RELEASE;
     }
     tcx.emit_spanned_lint(
         lint::builtin::STABLE_FEATURES,

compiler/rustc_span/src/symbol.rs

@@ -713,6 +713,7 @@ symbols! {
         encode,
         end,
         env,
+        env_CFG_RELEASE: env!("CFG_RELEASE"),
         eprint_macro,
         eprintln_macro,
         eq,