Make Cfg and CheckCfg non-generic.

They now only ever contains symbols.

compiler/rustc_interface/src/interface.rs

@@ -24,7 +24,6 @@ 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;
@@ -65,7 +64,7 @@ impl Compiler {
 }
 
 /// Converts strings provided as `--cfg [cfgspec]` into a `Cfg`.
-pub(crate) fn parse_cfg(handler: &EarlyErrorHandler, cfgs: Vec<String>) -> Cfg<Symbol> {
+pub(crate) fn parse_cfg(handler: &EarlyErrorHandler, cfgs: Vec<String>) -> Cfg {
     cfgs.into_iter()
         .map(|s| {
             let sess = ParseSess::with_silent_emitter(Some(format!(
@@ -116,11 +115,11 @@ pub(crate) fn parse_cfg(handler: &EarlyErrorHandler, cfgs: Vec<String>) -> Cfg<S
                 error!(r#"expected `key` or `key="value"`"#);
             }
         })
-        .collect::<Cfg<Symbol>>()
+        .collect::<Cfg>()
 }
 
 /// Converts strings provided as `--check-cfg [specs]` into a `CheckCfg`.
-pub(crate) fn parse_check_cfg(handler: &EarlyErrorHandler, specs: Vec<String>) -> CheckCfg<Symbol> {
+pub(crate) fn parse_check_cfg(handler: &EarlyErrorHandler, specs: Vec<String>) -> CheckCfg {
     // If any --check-cfg is passed then exhaustive_values and exhaustive_names
     // are enabled by default.
     let exhaustive_names = !specs.is_empty();

compiler/rustc_interface/src/tests.rs

@@ -26,19 +26,15 @@ 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::SourceFileHashAlgorithm;
-use rustc_span::{FileName, Symbol};
+use rustc_span::{FileName, SourceFileHashAlgorithm};
 use rustc_target::spec::{CodeModel, LinkerFlavorCli, MergeFunctions, PanicStrategy, RelocModel};
 use rustc_target::spec::{RelroLevel, SanitizerSet, SplitDebuginfo, StackProtector, TlsModel};
 use std::collections::{BTreeMap, BTreeSet};
 use std::num::NonZeroUsize;
 use std::path::{Path, PathBuf};
 use std::sync::Arc;
 
-fn mk_session(
-    handler: &mut EarlyErrorHandler,
-    matches: getopts::Matches,
-) -> (Session, Cfg<Symbol>) {
+fn mk_session(handler: &mut EarlyErrorHandler, matches: getopts::Matches) -> (Session, Cfg) {
     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

@@ -36,11 +36,7 @@ pub type MakeBackendFn = fn() -> Box<dyn CodegenBackend>;
 ///
 /// This is performed by checking whether a set of permitted features
 /// is available on the target machine, by querying the codegen backend.
-pub fn add_configuration(
-    cfg: &mut Cfg<Symbol>,
-    sess: &mut Session,
-    codegen_backend: &dyn CodegenBackend,
-) {
+pub fn add_configuration(cfg: &mut Cfg, sess: &mut Session, codegen_backend: &dyn CodegenBackend) {
     let tf = sym::target_feature;
 
     let unstable_target_features = codegen_backend.target_features(sess, true);
@@ -59,8 +55,8 @@ pub fn add_configuration(
 pub fn create_session(
     handler: &EarlyErrorHandler,
     sopts: config::Options,
-    cfg: Cfg<Symbol>,
-    mut check_cfg: CheckCfg<Symbol>,
+    cfg: Cfg,
+    mut check_cfg: CheckCfg,
     locale_resources: &'static [&'static str],
     file_loader: Option<Box<dyn FileLoader + Send + Sync + 'static>>,
     io: CompilerIO,

compiler/rustc_session/src/config.rs

@@ -1247,8 +1247,8 @@ pub const fn default_lib_output() -> CrateType {
     CrateType::Rlib
 }
 
-fn default_configuration(sess: &Session) -> Cfg<Symbol> {
-    // NOTE: This should be kept in sync with `CheckCfg::<Symbol>::fill_well_known` below.
+fn default_configuration(sess: &Session) -> Cfg {
+    // NOTE: This should be kept in sync with `CheckCfg::fill_well_known` below.
     let end = &sess.target.endian;
     let arch = &sess.target.arch;
     let wordsz = sess.target.pointer_width.to_string();
@@ -1358,32 +1358,21 @@ fn default_configuration(sess: &Session) -> Cfg<Symbol> {
 }
 
 /// The parsed `--cfg` options that define the compilation environment of the
-/// crate, used to drive conditional compilation. `T` is always `String` or
-/// `Symbol`. Strings are used temporarily very early on. Once the the main
-/// symbol interner is running, they are converted to symbols.
+/// crate, used to drive conditional compilation.
 ///
 /// An `FxIndexSet` is used to ensure deterministic ordering of error messages
 /// relating to `--cfg`.
-pub type Cfg<T> = FxIndexSet<(T, Option<T>)>;
+pub type Cfg = FxIndexSet<(Symbol, Option<Symbol>)>;
 
-/// The parsed `--check-cfg` options. The `<T>` structure is similar to `Cfg`.
-pub struct CheckCfg<T> {
+/// The parsed `--check-cfg` options.
+#[derive(Default)]
+pub struct CheckCfg {
     /// Is well known names activated
     pub exhaustive_names: bool,
     /// Is well known values activated
     pub exhaustive_values: bool,
     /// All the expected values for a config name
-    pub expecteds: FxHashMap<T, ExpectedValues<T>>,
-}
-
-impl<T> Default for CheckCfg<T> {
-    fn default() -> Self {
-        CheckCfg {
-            exhaustive_names: false,
-            exhaustive_values: false,
-            expecteds: FxHashMap::default(),
-        }
-    }
+    pub expecteds: FxHashMap<Symbol, ExpectedValues<Symbol>>,
 }
 
 pub enum ExpectedValues<T> {
@@ -1418,7 +1407,7 @@ impl<'a, T: Eq + Hash + Copy + 'a> Extend<&'a T> for ExpectedValues<T> {
     }
 }
 
-impl CheckCfg<Symbol> {
+impl CheckCfg {
     pub fn fill_well_known(&mut self, current_target: &Target) {
         if !self.exhaustive_values && !self.exhaustive_names {
             return;
@@ -1558,7 +1547,7 @@ impl CheckCfg<Symbol> {
     }
 }
 
-pub fn build_configuration(sess: &Session, mut user_cfg: Cfg<Symbol>) -> Cfg<Symbol> {
+pub fn build_configuration(sess: &Session, mut user_cfg: Cfg) -> Cfg {
     // Combine the configuration requested by the session (command line) with
     // some default and generated configuration items.
     let default_cfg = default_configuration(sess);

compiler/rustc_session/src/parse.rs

@@ -188,8 +188,8 @@ pub fn add_feature_diagnostics_for_issue(
 pub struct ParseSess {
     pub span_diagnostic: Handler,
     pub unstable_features: UnstableFeatures,
-    pub config: Cfg<Symbol>,
-    pub check_config: CheckCfg<Symbol>,
+    pub config: Cfg,
+    pub check_config: CheckCfg,
     pub edition: Edition,
     /// Places where raw identifiers were used. This is used to avoid complaining about idents
     /// clashing with keywords in new editions.