Eliminate confusing "globals" terminology.

There are some structures that are called "globals", but are they global
to a compilation session, and not truly global. I have always found this
highly confusing, so this commit renames them as "session globals" and
adds a comment explaining things.

Also, the commit fixes an unnecessary nesting of `set()` calls
`src/librustc_errors/json/tests.rs`

src/librustc_ast/attr/mod.rs

@@ -21,55 +21,61 @@ use log::debug;
 use std::iter;
 use std::ops::DerefMut;
 
-pub struct Globals {
+// Per-session global variables: this struct is stored in thread-local storage
+// in such a way that it is accessible without any kind of handle to all
+// threads within the compilation session, but is not accessible outside the
+// session.
+pub struct SessionGlobals {
     used_attrs: Lock<GrowableBitSet<AttrId>>,
     known_attrs: Lock<GrowableBitSet<AttrId>>,
-    rustc_span_globals: rustc_span::Globals,
+    span_session_globals: rustc_span::SessionGlobals,
 }
 
-impl Globals {
-    fn new(edition: Edition) -> Globals {
-        Globals {
+impl SessionGlobals {
+    fn new(edition: Edition) -> SessionGlobals {
+        SessionGlobals {
             // We have no idea how many attributes there will be, so just
             // initiate the vectors with 0 bits. We'll grow them as necessary.
             used_attrs: Lock::new(GrowableBitSet::new_empty()),
             known_attrs: Lock::new(GrowableBitSet::new_empty()),
-            rustc_span_globals: rustc_span::Globals::new(edition),
+            span_session_globals: rustc_span::SessionGlobals::new(edition),
         }
     }
 }
 
-pub fn with_globals<R>(edition: Edition, f: impl FnOnce() -> R) -> R {
-    let globals = Globals::new(edition);
-    GLOBALS.set(&globals, || rustc_span::GLOBALS.set(&globals.rustc_span_globals, f))
+pub fn with_session_globals<R>(edition: Edition, f: impl FnOnce() -> R) -> R {
+    let ast_session_globals = SessionGlobals::new(edition);
+    SESSION_GLOBALS.set(&ast_session_globals, || {
+        rustc_span::SESSION_GLOBALS.set(&ast_session_globals.span_session_globals, f)
+    })
 }
 
-pub fn with_default_globals<R>(f: impl FnOnce() -> R) -> R {
-    with_globals(DEFAULT_EDITION, f)
+pub fn with_default_session_globals<R>(f: impl FnOnce() -> R) -> R {
+    with_session_globals(DEFAULT_EDITION, f)
 }
 
-scoped_tls::scoped_thread_local!(pub static GLOBALS: Globals);
+scoped_tls::scoped_thread_local!(pub static SESSION_GLOBALS: SessionGlobals);
 
 pub fn mark_used(attr: &Attribute) {
     debug!("marking {:?} as used", attr);
-    GLOBALS.with(|globals| {
-        globals.used_attrs.lock().insert(attr.id);
+    SESSION_GLOBALS.with(|session_globals| {
+        session_globals.used_attrs.lock().insert(attr.id);
     });
 }
 
 pub fn is_used(attr: &Attribute) -> bool {
-    GLOBALS.with(|globals| globals.used_attrs.lock().contains(attr.id))
+    SESSION_GLOBALS.with(|session_globals| session_globals.used_attrs.lock().contains(attr.id))
 }
 
 pub fn mark_known(attr: &Attribute) {
     debug!("marking {:?} as known", attr);
-    GLOBALS.with(|globals| {
-        globals.known_attrs.lock().insert(attr.id);
+    SESSION_GLOBALS.with(|session_globals| {
+        session_globals.known_attrs.lock().insert(attr.id);
     });
 }
 
 pub fn is_known(attr: &Attribute) -> bool {
-    GLOBALS.with(|globals| globals.known_attrs.lock().contains(attr.id))
+    SESSION_GLOBALS.with(|session_globals| session_globals.known_attrs.lock().contains(attr.id))
 }
 
 pub fn is_known_lint_tool(m_item: Ident) -> bool {

src/librustc_ast/lib.rs

@@ -43,7 +43,7 @@ pub mod util {
 
 pub mod ast;
 pub mod attr;
-pub use attr::{with_default_globals, with_globals, GLOBALS};
+pub use attr::{with_default_session_globals, with_session_globals, SESSION_GLOBALS};
 pub mod crate_disambiguator;
 pub mod entry;
 pub mod expand;

src/librustc_ast/util/lev_distance/tests.rs

@@ -21,8 +21,8 @@ fn test_lev_distance() {
 
 #[test]
 fn test_find_best_match_for_name() {
-    use crate::with_default_globals;
-    with_default_globals(|| {
+    use crate::with_default_session_globals;
+    with_default_session_globals(|| {
         let input = vec![Symbol::intern("aaab"), Symbol::intern("aaabc")];
         assert_eq!(
             find_best_match_for_name(input.iter(), "aaaa", None),

src/librustc_ast_pretty/pprust/tests.rs

@@ -1,7 +1,7 @@
 use super::*;
 
 use rustc_ast::ast;
-use rustc_ast::with_default_globals;
+use rustc_ast::with_default_session_globals;
 use rustc_span::source_map::respan;
 use rustc_span::symbol::Ident;
 
@@ -25,7 +25,7 @@ fn variant_to_string(var: &ast::Variant) -> String {
 
 #[test]
 fn test_fun_to_string() {
-    with_default_globals(|| {
+    with_default_session_globals(|| {
         let abba_ident = Ident::from_str("abba");
 
         let decl =
@@ -40,7 +40,7 @@ fn test_fun_to_string() {
 
 #[test]
 fn test_variant_to_string() {
-    with_default_globals(|| {
+    with_default_session_globals(|| {
         let ident = Ident::from_str("principal_skinner");
 
         let var = ast::Variant {

src/librustc_errors/json/tests.rs

@@ -39,16 +39,16 @@ impl<T: Write> Write for Shared<T> {
     }
 }
 
-fn with_default_globals(f: impl FnOnce()) {
-    let globals = rustc_span::Globals::new(rustc_span::edition::DEFAULT_EDITION);
-    rustc_span::GLOBALS.set(&globals, || rustc_span::GLOBALS.set(&globals, f))
+fn with_default_session_globals(f: impl FnOnce()) {
+    let session_globals = rustc_span::SessionGlobals::new(rustc_span::edition::DEFAULT_EDITION);
+    rustc_span::SESSION_GLOBALS.set(&session_globals, f);
 }
 
 /// Test the span yields correct positions in JSON.
 fn test_positions(code: &str, span: (u32, u32), expected_output: SpanTestData) {
     let expected_output = TestData { spans: vec![expected_output] };
 
-    with_default_globals(|| {
+    with_default_session_globals(|| {
         let sm = Lrc::new(SourceMap::new(FilePathMapping::empty()));
         sm.new_source_file(Path::new("test.rs").to_owned().into(), code.to_owned());
 

src/librustc_expand/mut_visit/tests.rs

@@ -2,7 +2,7 @@ use crate::tests::{matches_codepattern, string_to_crate};
 
 use rustc_ast::ast;
 use rustc_ast::mut_visit::{self, MutVisitor};
-use rustc_ast::with_default_globals;
+use rustc_ast::with_default_session_globals;
 use rustc_ast_pretty::pprust;
 use rustc_span::symbol::Ident;
 
@@ -38,7 +38,7 @@ macro_rules! assert_pred {
 // Make sure idents get transformed everywhere.
 #[test]
 fn ident_transformation() {
-    with_default_globals(|| {
+    with_default_session_globals(|| {
         let mut zz_visitor = ToZzIdentMutVisitor;
         let mut krate =
             string_to_crate("#[a] mod b {fn c (d : e, f : g) {h!(i,j,k);l;m}}".to_string());
@@ -55,7 +55,7 @@ fn ident_transformation() {
 // Make sure idents get transformed even inside macro defs.
 #[test]
 fn ident_transformation_in_defs() {
-    with_default_globals(|| {
+    with_default_session_globals(|| {
         let mut zz_visitor = ToZzIdentMutVisitor;
         let mut krate = string_to_crate(
             "macro_rules! a {(b $c:expr $(d $e:token)f+ => \

src/librustc_expand/parse/lexer/tests.rs

@@ -1,6 +1,6 @@
 use rustc_ast::token::{self, Token, TokenKind};
 use rustc_ast::util::comments::is_doc_comment;
-use rustc_ast::with_default_globals;
+use rustc_ast::with_default_session_globals;
 use rustc_data_structures::sync::Lrc;
 use rustc_errors::{emitter::EmitterWriter, Handler};
 use rustc_parse::lexer::StringReader;
@@ -33,7 +33,7 @@ fn setup<'a>(sm: &SourceMap, sess: &'a ParseSess, teststr: String) -> StringRead
 
 #[test]
 fn t1() {
-    with_default_globals(|| {
+    with_default_session_globals(|| {
         let sm = Lrc::new(SourceMap::new(FilePathMapping::empty()));
         let sh = mk_sess(sm.clone());
         let mut string_reader = setup(
@@ -79,7 +79,7 @@ fn mk_lit(kind: token::LitKind, symbol: &str, suffix: Option<&str>) -> TokenKind
 
 #[test]
 fn doublecolon_parsing() {
-    with_default_globals(|| {
+    with_default_session_globals(|| {
         let sm = Lrc::new(SourceMap::new(FilePathMapping::empty()));
         let sh = mk_sess(sm.clone());
         check_tokenization(
@@ -91,7 +91,7 @@ fn doublecolon_parsing() {
 
 #[test]
 fn doublecolon_parsing_2() {
-    with_default_globals(|| {
+    with_default_session_globals(|| {
         let sm = Lrc::new(SourceMap::new(FilePathMapping::empty()));
         let sh = mk_sess(sm.clone());
         check_tokenization(
@@ -103,7 +103,7 @@ fn doublecolon_parsing_2() {
 
 #[test]
 fn doublecolon_parsing_3() {
-    with_default_globals(|| {
+    with_default_session_globals(|| {
         let sm = Lrc::new(SourceMap::new(FilePathMapping::empty()));
         let sh = mk_sess(sm.clone());
         check_tokenization(
@@ -115,7 +115,7 @@ fn doublecolon_parsing_3() {
 
 #[test]
 fn doublecolon_parsing_4() {
-    with_default_globals(|| {
+    with_default_session_globals(|| {
         let sm = Lrc::new(SourceMap::new(FilePathMapping::empty()));
         let sh = mk_sess(sm.clone());
         check_tokenization(
@@ -127,7 +127,7 @@ fn doublecolon_parsing_4() {
 
 #[test]
 fn character_a() {
-    with_default_globals(|| {
+    with_default_session_globals(|| {
         let sm = Lrc::new(SourceMap::new(FilePathMapping::empty()));
         let sh = mk_sess(sm.clone());
         assert_eq!(setup(&sm, &sh, "'a'".to_string()).next_token(), mk_lit(token::Char, "a", None),);
@@ -136,7 +136,7 @@ fn character_a() {
 
 #[test]
 fn character_space() {
-    with_default_globals(|| {
+    with_default_session_globals(|| {
         let sm = Lrc::new(SourceMap::new(FilePathMapping::empty()));
         let sh = mk_sess(sm.clone());
         assert_eq!(setup(&sm, &sh, "' '".to_string()).next_token(), mk_lit(token::Char, " ", None),);
@@ -145,7 +145,7 @@ fn character_space() {
 
 #[test]
 fn character_escaped() {
-    with_default_globals(|| {
+    with_default_session_globals(|| {
         let sm = Lrc::new(SourceMap::new(FilePathMapping::empty()));
         let sh = mk_sess(sm.clone());
         assert_eq!(
@@ -157,7 +157,7 @@ fn character_escaped() {
 
 #[test]
 fn lifetime_name() {
-    with_default_globals(|| {
+    with_default_session_globals(|| {
         let sm = Lrc::new(SourceMap::new(FilePathMapping::empty()));
         let sh = mk_sess(sm.clone());
         assert_eq!(
@@ -169,7 +169,7 @@ fn lifetime_name() {
 
 #[test]
 fn raw_string() {
-    with_default_globals(|| {
+    with_default_session_globals(|| {
         let sm = Lrc::new(SourceMap::new(FilePathMapping::empty()));
         let sh = mk_sess(sm.clone());
         assert_eq!(
@@ -181,7 +181,7 @@ fn raw_string() {
 
 #[test]
 fn literal_suffixes() {
-    with_default_globals(|| {
+    with_default_session_globals(|| {
         let sm = Lrc::new(SourceMap::new(FilePathMapping::empty()));
         let sh = mk_sess(sm.clone());
         macro_rules! test {
@@ -232,7 +232,7 @@ fn line_doc_comments() {
 
 #[test]
 fn nested_block_comments() {
-    with_default_globals(|| {
+    with_default_session_globals(|| {
         let sm = Lrc::new(SourceMap::new(FilePathMapping::empty()));
         let sh = mk_sess(sm.clone());
         let mut lexer = setup(&sm, &sh, "/* /* */ */'a'".to_string());
@@ -243,7 +243,7 @@ fn nested_block_comments() {
 
 #[test]
 fn crlf_comments() {
-    with_default_globals(|| {
+    with_default_session_globals(|| {
         let sm = Lrc::new(SourceMap::new(FilePathMapping::empty()));
         let sh = mk_sess(sm.clone());
         let mut lexer = setup(&sm, &sh, "// test\r\n/// test\r\n".to_string());