syntax_pos: Remove the duplicate global edition

It was introduced to avoid going through `hygiene_data`, but now it's read only once, when `ParseSess` is created, so going through a lock is ok.

src/libsyntax/parse/lexer/tests.rs

@@ -1,41 +1,17 @@
 use super::*;
 
-use crate::ast::CrateConfig;
 use crate::symbol::Symbol;
 use crate::source_map::{SourceMap, FilePathMapping};
-use crate::feature_gate::UnstableFeatures;
 use crate::parse::token;
-use crate::diagnostics::plugin::ErrorMap;
 use crate::with_default_globals;
 use std::io;
 use std::path::PathBuf;
-use syntax_pos::{BytePos, Span, edition::Edition};
-use rustc_data_structures::fx::{FxHashSet, FxHashMap};
-use rustc_data_structures::sync::{Lock, Once};
+use errors::{Handler, emitter::EmitterWriter};
+use syntax_pos::{BytePos, Span};
 
 fn mk_sess(sm: Lrc<SourceMap>) -> ParseSess {
-    let emitter = errors::emitter::EmitterWriter::new(Box::new(io::sink()),
-                                                        Some(sm.clone()),
-                                                        false,
-                                                        false,
-                                                        false);
-    ParseSess {
-        span_diagnostic: errors::Handler::with_emitter(true, None, Box::new(emitter)),
-        unstable_features: UnstableFeatures::from_environment(),
-        config: CrateConfig::default(),
-        included_mod_stack: Lock::new(Vec::new()),
-        source_map: sm,
-        missing_fragment_specifiers: Lock::new(FxHashSet::default()),
-        raw_identifier_spans: Lock::new(Vec::new()),
-        registered_diagnostics: Lock::new(ErrorMap::new()),
-        buffered_lints: Lock::new(vec![]),
-        edition: Edition::from_session(),
-        ambiguous_block_expr_parse: Lock::new(FxHashMap::default()),
-        param_attr_spans: Lock::new(Vec::new()),
-        let_chains_spans: Lock::new(Vec::new()),
-        async_closure_spans: Lock::new(Vec::new()),
-        injected_crate_name: Once::new(),
-    }
+    let emitter = EmitterWriter::new(Box::new(io::sink()), Some(sm.clone()), false, false, false);
+    ParseSess::with_span_handler(Handler::with_emitter(true, None, Box::new(emitter)), sm)
 }
 
 // open a string reader for the given string

src/libsyntax/parse/mod.rs

@@ -16,6 +16,7 @@ use errors::{Applicability, FatalError, Level, Handler, ColorConfig, Diagnostic,
 use rustc_data_structures::sync::{Lrc, Lock, Once};
 use syntax_pos::{Span, SourceFile, FileName, MultiSpan};
 use syntax_pos::edition::Edition;
+use syntax_pos::hygiene::ExpnId;
 
 use rustc_data_structures::fx::{FxHashSet, FxHashMap};
 use std::borrow::Cow;
@@ -86,7 +87,7 @@ impl ParseSess {
             included_mod_stack: Lock::new(vec![]),
             source_map,
             buffered_lints: Lock::new(vec![]),
-            edition: Edition::from_session(),
+            edition: ExpnId::root().expn_info().edition,
             ambiguous_block_expr_parse: Lock::new(FxHashMap::default()),
             param_attr_spans: Lock::new(Vec::new()),
             let_chains_spans: Lock::new(Vec::new()),

src/libsyntax_pos/edition.rs

@@ -1,7 +1,6 @@
 use crate::symbol::{Symbol, sym};
 use std::fmt;
 use std::str::FromStr;
-use crate::GLOBALS;
 
 /// The edition of the compiler (RFC 2052)
 #[derive(Clone, Copy, Hash, PartialEq, PartialOrd, Debug, RustcEncodable, RustcDecodable, Eq)]
@@ -39,10 +38,6 @@ impl fmt::Display for Edition {
 }
 
 impl Edition {
-    pub fn from_session() -> Edition {
-        GLOBALS.with(|globals| globals.edition)
-    }
-
     pub fn lint_name(&self) -> &'static str {
         match *self {
             Edition::Edition2015 => "rust_2015_compatibility",

src/libsyntax_pos/lib.rs

@@ -49,7 +49,6 @@ pub struct Globals {
     symbol_interner: Lock<symbol::Interner>,
     span_interner: Lock<span_encoding::SpanInterner>,
     hygiene_data: Lock<hygiene::HygieneData>,
-    edition: Edition,
 }
 
 impl Globals {
@@ -58,7 +57,6 @@ impl Globals {
             symbol_interner: Lock::new(symbol::Interner::fresh()),
             span_interner: Lock::new(span_encoding::SpanInterner::default()),
             hygiene_data: Lock::new(hygiene::HygieneData::new(edition)),
-            edition,
         }
     }
 }