Deduplicate CrateConfig

Author: Mark-Simulacrum

src/librustc_session/config.rs

@@ -12,13 +12,11 @@ use rustc_data_structures::impl_stable_hash_via_hash;
 use rustc_target::spec::{LinkerFlavor, MergeFunctions, PanicStrategy, RelroLevel};
 use rustc_target::spec::{Target, TargetTriple};
 
-// Duplicated from syntax::ast for now
-type CrateConfig = FxHashSet<(Symbol, Option<Symbol>)>;
-
 use syntax_pos::source_map::{FileName, FilePathMapping};
 use syntax_pos::edition::{Edition, EDITION_NAME_LIST, DEFAULT_EDITION};
 use syntax_pos::symbol::{sym, Symbol};
 use rustc_feature::UnstableFeatures;
+use crate::parse::CrateConfig;
 
 use rustc_errors::emitter::HumanReadableErrorType;
 use rustc_errors::{ColorConfig, FatalError, Handler};

src/librustc_session/parse.rs

@@ -16,8 +16,9 @@ use syntax_pos::source_map::{SourceMap, FilePathMapping};
 use std::path::PathBuf;
 use std::str;
 
-// Duplicated from syntax::ast for now
-type CrateConfig = FxHashSet<(Symbol, Option<Symbol>)>;
+/// The set of keys (and, optionally, values) that define the compilation
+/// environment of the crate, used to drive conditional compilation.
+pub type CrateConfig = FxHashSet<(Symbol, Option<Symbol>)>;
 
 /// Collected spans during parsing for places where a certain feature was
 /// used and should be feature gated accordingly in `check_crate`.

src/libsyntax/ast.rs

@@ -32,7 +32,6 @@ use crate::tokenstream::{TokenStream, TokenTree, DelimSpan};
 use syntax_pos::symbol::{kw, sym, Symbol};
 use syntax_pos::{Span, DUMMY_SP};
 
-use rustc_data_structures::fx::FxHashSet;
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_data_structures::sync::Lrc;
 use rustc_data_structures::thin_vec::ThinVec;
@@ -431,9 +430,7 @@ pub struct WhereEqPredicate {
     pub rhs_ty: P<Ty>,
 }
 
-/// The set of `MetaItem`s that define the compilation environment of the crate,
-/// used to drive conditional compilation.
-pub type CrateConfig = FxHashSet<(Name, Option<Symbol>)>;
+pub use rustc_session::parse::CrateConfig;
 
 #[derive(Clone, RustcEncodable, RustcDecodable, Debug)]
 pub struct Crate {