Rollup merge of #117268 - nnethercote:rustc_interface, r=oli-obk

`rustc_interface` cleanups

Particularly in and around `--cfg` and `--check-cfg` handling.

r? `@oli-obk`

compiler/rustc_session/src/config.rs

@@ -9,14 +9,13 @@ use crate::utils::{CanonicalizedPath, NativeLib, NativeLibKind};
 use crate::{lint, HashStableContext};
 use crate::{EarlyErrorHandler, Session};
 
-use rustc_data_structures::fx::{FxHashMap, FxHashSet};
+use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexSet};
 use rustc_data_structures::stable_hasher::{StableOrd, ToStableHashKey};
 use rustc_target::abi::Align;
 use rustc_target::spec::LinkSelfContainedComponents;
 use rustc_target::spec::{PanicStrategy, RelocModel, SanitizerSet, SplitDebuginfo};
 use rustc_target::spec::{Target, TargetTriple, TargetWarnings, TARGETS};
 
-use crate::parse::{CrateCheckConfig, CrateConfig};
 use rustc_feature::UnstableFeatures;
 use rustc_span::edition::{Edition, DEFAULT_EDITION, EDITION_NAME_LIST, LATEST_STABLE_EDITION};
 use rustc_span::source_map::{FileName, FilePathMapping};
@@ -1248,8 +1247,8 @@ pub const fn default_lib_output() -> CrateType {
     CrateType::Rlib
 }
 
-fn default_configuration(sess: &Session) -> CrateConfig {
-    // NOTE: This should be kept in sync with `CrateCheckConfig::fill_well_known` below.
+fn default_configuration(sess: &Session) -> Cfg<Symbol> {
+    // NOTE: This should be kept in sync with `CheckCfg::<Symbol>::fill_well_known` below.
     let end = &sess.target.endian;
     let arch = &sess.target.arch;
     let wordsz = sess.target.pointer_width.to_string();
@@ -1265,7 +1264,7 @@ fn default_configuration(sess: &Session) -> CrateConfig {
         sess.emit_fatal(err);
     });
 
-    let mut ret = CrateConfig::default();
+    let mut ret = Cfg::default();
     ret.reserve(7); // the minimum number of insertions
     // Target bindings.
     ret.insert((sym::target_os, Some(Symbol::intern(os))));
@@ -1358,15 +1357,17 @@ fn default_configuration(sess: &Session) -> CrateConfig {
     ret
 }
 
-/// Converts the crate `cfg!` configuration from `String` to `Symbol`.
-/// `rustc_interface::interface::Config` accepts this in the compiler configuration,
-/// but the symbol interner is not yet set up then, so we must convert it later.
-pub fn to_crate_config(cfg: FxHashSet<(String, Option<String>)>) -> CrateConfig {
-    cfg.into_iter().map(|(a, b)| (Symbol::intern(&a), b.map(|b| Symbol::intern(&b)))).collect()
-}
+/// 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.
+///
+/// An `FxIndexSet` is used to ensure deterministic ordering of error messages
+/// relating to `--cfg`.
+pub type Cfg<T> = FxIndexSet<(T, Option<T>)>;
 
-/// The parsed `--check-cfg` options
-pub struct CheckCfg<T = String> {
+/// The parsed `--check-cfg` options. The `<T>` structure is similar to `Cfg`.
+pub struct CheckCfg<T> {
     /// Is well known names activated
     pub exhaustive_names: bool,
     /// Is well known values activated
@@ -1385,8 +1386,8 @@ impl<T> Default for CheckCfg<T> {
     }
 }
 
-impl<T> CheckCfg<T> {
-    fn map_data<O: Eq + Hash>(self, f: impl Fn(T) -> O) -> CheckCfg<O> {
+impl CheckCfg<String> {
+    pub fn intern(self) -> CheckCfg<Symbol> {
         CheckCfg {
             exhaustive_names: self.exhaustive_names,
             exhaustive_values: self.exhaustive_values,
@@ -1395,10 +1396,10 @@ impl<T> CheckCfg<T> {
                 .into_iter()
                 .map(|(name, values)| {
                     (
-                        f(name),
+                        Symbol::intern(&name),
                         match values {
                             ExpectedValues::Some(values) => ExpectedValues::Some(
-                                values.into_iter().map(|b| b.map(|b| f(b))).collect(),
+                                values.into_iter().map(|b| b.map(|b| Symbol::intern(&b))).collect(),
                             ),
                             ExpectedValues::Any => ExpectedValues::Any,
                         },
@@ -1441,14 +1442,7 @@ impl<'a, T: Eq + Hash + Copy + 'a> Extend<&'a T> for ExpectedValues<T> {
     }
 }
 
-/// Converts the crate `--check-cfg` options from `String` to `Symbol`.
-/// `rustc_interface::interface::Config` accepts this in the compiler configuration,
-/// but the symbol interner is not yet set up then, so we must convert it later.
-pub fn to_crate_check_config(cfg: CheckCfg) -> CrateCheckConfig {
-    cfg.map_data(|s| Symbol::intern(&s))
-}
-
-impl CrateCheckConfig {
+impl CheckCfg<Symbol> {
     pub fn fill_well_known(&mut self, current_target: &Target) {
         if !self.exhaustive_values && !self.exhaustive_names {
             return;
@@ -1588,7 +1582,13 @@ impl CrateCheckConfig {
     }
 }
 
-pub fn build_configuration(sess: &Session, mut user_cfg: CrateConfig) -> CrateConfig {
+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();
+
     // 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

@@ -1,7 +1,7 @@
 //! Contains `ParseSess` which holds state living beyond what one `Parser` might.
 //! It also serves as an input to the parser itself.
 
-use crate::config::CheckCfg;
+use crate::config::{Cfg, CheckCfg};
 use crate::errors::{
     CliFeatureDiagnosticHelp, FeatureDiagnosticForIssue, FeatureDiagnosticHelp, FeatureGateError,
 };
@@ -9,7 +9,7 @@ use crate::lint::{
     builtin::UNSTABLE_SYNTAX_PRE_EXPANSION, BufferedEarlyLint, BuiltinLintDiagnostics, Lint, LintId,
 };
 use rustc_ast::node_id::NodeId;
-use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexSet};
+use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 use rustc_data_structures::sync::{AppendOnlyVec, Lock, Lrc};
 use rustc_errors::{emitter::SilentEmitter, Handler};
 use rustc_errors::{
@@ -25,11 +25,6 @@ use rustc_span::{Span, Symbol};
 use rustc_ast::attr::AttrIdGenerator;
 use std::str;
 
-/// The set of keys (and, optionally, values) that define the compilation
-/// environment of the crate, used to drive conditional compilation.
-pub type CrateConfig = FxIndexSet<(Symbol, Option<Symbol>)>;
-pub type CrateCheckConfig = CheckCfg<Symbol>;
-
 /// Collected spans during parsing for places where a certain feature was
 /// used and should be feature gated accordingly in `check_crate`.
 #[derive(Default)]
@@ -193,8 +188,8 @@ pub fn add_feature_diagnostics_for_issue(
 pub struct ParseSess {
     pub span_diagnostic: Handler,
     pub unstable_features: UnstableFeatures,
-    pub config: CrateConfig,
-    pub check_config: CrateCheckConfig,
+    pub config: Cfg<Symbol>,
+    pub check_config: CheckCfg<Symbol>,
     pub edition: Edition,
     /// Places where raw identifiers were used. This is used to avoid complaining about idents
     /// clashing with keywords in new editions.
@@ -237,8 +232,8 @@ impl ParseSess {
         Self {
             span_diagnostic: handler,
             unstable_features: UnstableFeatures::from_environment(None),
-            config: FxIndexSet::default(),
-            check_config: CrateCheckConfig::default(),
+            config: Cfg::default(),
+            check_config: CheckCfg::default(),
             edition: ExpnId::root().expn_data().edition,
             raw_identifier_spans: Default::default(),
             bad_unicode_identifiers: Lock::new(Default::default()),