Change cfg parsers to produce symbols instead of strings.

compiler/rustc_interface/src/interface.rs

@@ -24,6 +24,7 @@ use rustc_session::Session;
 use rustc_session::{lint, EarlyErrorHandler};
 use rustc_span::source_map::{FileLoader, FileName};
 use rustc_span::symbol::sym;
+use rustc_span::Symbol;
 use std::path::PathBuf;
 use std::result;
 use std::sync::Arc;
@@ -64,7 +65,7 @@ impl Compiler {
 }
 
 /// Converts strings provided as `--cfg [cfgspec]` into a `Cfg`.
-pub(crate) fn parse_cfg(handler: &EarlyErrorHandler, cfgs: Vec<String>) -> Cfg<String> {
+pub(crate) fn parse_cfg(handler: &EarlyErrorHandler, cfgs: Vec<String>) -> Cfg<Symbol> {
     cfgs.into_iter()
         .map(|s| {
             let sess = ParseSess::with_silent_emitter(Some(format!(
@@ -94,10 +95,7 @@ pub(crate) fn parse_cfg(handler: &EarlyErrorHandler, cfgs: Vec<String>) -> Cfg<S
                             }
                             MetaItemKind::NameValue(..) | MetaItemKind::Word => {
                                 let ident = meta_item.ident().expect("multi-segment cfg key");
-                                return (
-                                    ident.name.to_string(),
-                                    meta_item.value_str().map(|sym| sym.to_string()),
-                                );
+                                return (ident.name, meta_item.value_str());
                             }
                         }
                     }
@@ -118,11 +116,11 @@ pub(crate) fn parse_cfg(handler: &EarlyErrorHandler, cfgs: Vec<String>) -> Cfg<S
                 error!(r#"expected `key` or `key="value"`"#);
             }
         })
-        .collect::<Cfg<String>>()
+        .collect::<Cfg<Symbol>>()
 }
 
 /// Converts strings provided as `--check-cfg [specs]` into a `CheckCfg`.
-pub(crate) fn parse_check_cfg(handler: &EarlyErrorHandler, specs: Vec<String>) -> CheckCfg<String> {
+pub(crate) fn parse_check_cfg(handler: &EarlyErrorHandler, specs: Vec<String>) -> CheckCfg<Symbol> {
     // If any --check-cfg is passed then exhaustive_values and exhaustive_names
     // are enabled by default.
     let exhaustive_names = !specs.is_empty();
@@ -179,10 +177,7 @@ pub(crate) fn parse_check_cfg(handler: &EarlyErrorHandler, specs: Vec<String>) -
             for arg in args {
                 if arg.is_word() && arg.ident().is_some() {
                     let ident = arg.ident().expect("multi-segment cfg key");
-                    check_cfg
-                        .expecteds
-                        .entry(ident.name.to_string())
-                        .or_insert(ExpectedValues::Any);
+                    check_cfg.expecteds.entry(ident.name).or_insert(ExpectedValues::Any);
                 } else {
                     error!("`names()` arguments must be simple identifiers");
                 }
@@ -200,7 +195,7 @@ pub(crate) fn parse_check_cfg(handler: &EarlyErrorHandler, specs: Vec<String>) -
                     let ident = name.ident().expect("multi-segment cfg key");
                     let expected_values = check_cfg
                         .expecteds
-                        .entry(ident.name.to_string())
+                        .entry(ident.name)
                         .and_modify(|expected_values| match expected_values {
                             ExpectedValues::Some(_) => {}
                             ExpectedValues::Any => {
@@ -217,7 +212,7 @@ pub(crate) fn parse_check_cfg(handler: &EarlyErrorHandler, specs: Vec<String>) -
 
                     for val in values {
                         if let Some(LitKind::Str(s, _)) = val.lit().map(|lit| &lit.kind) {
-                            expected_values.insert(Some(s.to_string()));
+                            expected_values.insert(Some(*s));
                         } else {
                             error!("`values()` arguments must be string literals");
                         }
@@ -271,10 +266,8 @@ pub(crate) fn parse_check_cfg(handler: &EarlyErrorHandler, specs: Vec<String>) -
                     values_specified = true;
 
                     for arg in args {
-                        if let Some(LitKind::Str(s, _)) =
-                            arg.lit().map(|lit| &lit.kind)
-                        {
-                            values.insert(Some(s.to_string()));
+                        if let Some(LitKind::Str(s, _)) = arg.lit().map(|lit| &lit.kind) {
+                            values.insert(Some(*s));
                         } else if arg.has_name(sym::any)
                             && let Some(args) = arg.meta_item_list()
                         {
@@ -322,7 +315,7 @@ pub(crate) fn parse_check_cfg(handler: &EarlyErrorHandler, specs: Vec<String>) -
                 for name in names {
                     check_cfg
                         .expecteds
-                        .entry(name.to_string())
+                        .entry(name.name)
                         .and_modify(|v| match v {
                             ExpectedValues::Some(v) if !values_any_specified => {
                                 v.extend(values.clone())

compiler/rustc_interface/src/tests.rs

@@ -26,8 +26,8 @@ use rustc_session::{build_session, getopts, Session};
 use rustc_session::{CompilerIO, EarlyErrorHandler};
 use rustc_span::edition::{Edition, DEFAULT_EDITION};
 use rustc_span::symbol::sym;
-use rustc_span::FileName;
 use rustc_span::SourceFileHashAlgorithm;
+use rustc_span::{FileName, Symbol};
 use rustc_target::spec::{CodeModel, LinkerFlavorCli, MergeFunctions, PanicStrategy, RelocModel};
 use rustc_target::spec::{RelroLevel, SanitizerSet, SplitDebuginfo, StackProtector, TlsModel};
 use std::collections::{BTreeMap, BTreeSet};
@@ -38,7 +38,7 @@ use std::sync::Arc;
 fn mk_session(
     handler: &mut EarlyErrorHandler,
     matches: getopts::Matches,
-) -> (Session, Cfg<String>) {
+) -> (Session, Cfg<Symbol>) {
     let registry = registry::Registry::new(&[]);
     let sessopts = build_session_options(handler, &matches);
     let cfg = parse_cfg(handler, matches.opt_strs("cfg"));

compiler/rustc_interface/src/util.rs

@@ -59,8 +59,8 @@ pub fn add_configuration(
 pub fn create_session(
     handler: &EarlyErrorHandler,
     sopts: config::Options,
-    cfg: Cfg<String>,
-    check_cfg: CheckCfg<String>,
+    cfg: Cfg<Symbol>,
+    mut check_cfg: CheckCfg<Symbol>,
     locale_resources: &'static [&'static str],
     file_loader: Option<Box<dyn FileLoader + Send + Sync + 'static>>,
     io: CompilerIO,
@@ -123,7 +123,6 @@ pub fn create_session(
     let mut cfg = config::build_configuration(&sess, cfg);
     add_configuration(&mut cfg, &mut sess, &*codegen_backend);
 
-    let mut check_cfg = check_cfg.intern();
     check_cfg.fill_well_known(&sess.target);
 
     // These configs use symbols, rather than strings.

compiler/rustc_session/src/config.rs

@@ -1386,30 +1386,6 @@ impl<T> Default for CheckCfg<T> {
     }
 }
 
-impl CheckCfg<String> {
-    pub fn intern(self) -> CheckCfg<Symbol> {
-        CheckCfg {
-            exhaustive_names: self.exhaustive_names,
-            exhaustive_values: self.exhaustive_values,
-            expecteds: self
-                .expecteds
-                .into_iter()
-                .map(|(name, values)| {
-                    (
-                        Symbol::intern(&name),
-                        match values {
-                            ExpectedValues::Some(values) => ExpectedValues::Some(
-                                values.into_iter().map(|b| b.map(|b| Symbol::intern(&b))).collect(),
-                            ),
-                            ExpectedValues::Any => ExpectedValues::Any,
-                        },
-                    )
-                })
-                .collect(),
-        }
-    }
-}
-
 pub enum ExpectedValues<T> {
     Some(FxHashSet<Option<T>>),
     Any,
@@ -1582,13 +1558,7 @@ impl CheckCfg<Symbol> {
     }
 }
 
-pub fn build_configuration(sess: &Session, user_cfg: Cfg<String>) -> Cfg<Symbol> {
-    // We can now intern these strings.
-    let mut user_cfg: Cfg<Symbol> = user_cfg
-        .into_iter()
-        .map(|(a, b)| (Symbol::intern(&a), b.map(|b| Symbol::intern(&b))))
-        .collect();
-
+pub fn build_configuration(sess: &Session, mut user_cfg: Cfg<Symbol>) -> Cfg<Symbol> {
     // Combine the configuration requested by the session (command line) with
     // some default and generated configuration items.
     let default_cfg = default_configuration(sess);