3 files changed, 14 insertions, 13 deletions

diff --git a/compiler/rustc_interface/src/interface.rs b/compiler/rustc_interface/src/interface.rs
index a1090ee316d..086c49c7397 100644
--- a/compiler/rustc_interface/src/interface.rs
+++ b/compiler/rustc_interface/src/interface.rs
@@ -76,7 +76,7 @@ impl Compiler {
 
 /// Converts strings provided as `--cfg [cfgspec]` into a `crate_cfg`.
 pub fn parse_cfgspecs(cfgspecs: Vec<String>) -> FxHashSet<(String, Option<String>)> {
-    rustc_span::with_default_session_globals(move || {
+    rustc_span::create_default_session_if_not_set_then(move |_| {
         let cfg = cfgspecs
             .into_iter()
             .map(|s| {
diff --git a/compiler/rustc_interface/src/tests.rs b/compiler/rustc_interface/src/tests.rs
index b252409a92a..a053253ec16 100644
--- a/compiler/rustc_interface/src/tests.rs
+++ b/compiler/rustc_interface/src/tests.rs
@@ -107,7 +107,7 @@ fn assert_non_crate_hash_different(x: &Options, y: &Options) {
 // When the user supplies --test we should implicitly supply --cfg test
 #[test]
 fn test_switch_implies_cfg_test() {
-    rustc_span::with_default_session_globals(|| {
+    rustc_span::create_default_session_globals_then(|| {
         let matches = optgroups().parse(&["--test".to_string()]).unwrap();
         let (sess, cfg) = mk_session(matches);
         let cfg = build_configuration(&sess, to_crate_config(cfg));
@@ -118,7 +118,7 @@ fn test_switch_implies_cfg_test() {
 // When the user supplies --test and --cfg test, don't implicitly add another --cfg test
 #[test]
 fn test_switch_implies_cfg_test_unless_cfg_test() {
-    rustc_span::with_default_session_globals(|| {
+    rustc_span::create_default_session_globals_then(|| {
         let matches = optgroups().parse(&["--test".to_string(), "--cfg=test".to_string()]).unwrap();
         let (sess, cfg) = mk_session(matches);
         let cfg = build_configuration(&sess, to_crate_config(cfg));
@@ -130,20 +130,20 @@ fn test_switch_implies_cfg_test_unless_cfg_test() {
 
 #[test]
 fn test_can_print_warnings() {
-    rustc_span::with_default_session_globals(|| {
+    rustc_span::create_default_session_globals_then(|| {
         let matches = optgroups().parse(&["-Awarnings".to_string()]).unwrap();
         let (sess, _) = mk_session(matches);
         assert!(!sess.diagnostic().can_emit_warnings());
     });
 
-    rustc_span::with_default_session_globals(|| {
+    rustc_span::create_default_session_globals_then(|| {
         let matches =
             optgroups().parse(&["-Awarnings".to_string(), "-Dwarnings".to_string()]).unwrap();
         let (sess, _) = mk_session(matches);
         assert!(sess.diagnostic().can_emit_warnings());
     });
 
-    rustc_span::with_default_session_globals(|| {
+    rustc_span::create_default_session_globals_then(|| {
         let matches = optgroups().parse(&["-Adead_code".to_string()]).unwrap();
         let (sess, _) = mk_session(matches);
         assert!(sess.diagnostic().can_emit_warnings());
diff --git a/compiler/rustc_interface/src/util.rs b/compiler/rustc_interface/src/util.rs
index d1d0eee365d..4f51ce62042 100644
--- a/compiler/rustc_interface/src/util.rs
+++ b/compiler/rustc_interface/src/util.rs
@@ -150,7 +150,7 @@ pub fn setup_callbacks_and_run_in_thread_pool_with_globals<F: FnOnce() -> R + Se
     crate::callbacks::setup_callbacks();
 
     let main_handler = move || {
-        rustc_span::with_session_globals(edition, || {
+        rustc_span::create_session_globals_then(edition, || {
             io::set_output_capture(stderr.clone());
             f()
         })
@@ -171,12 +171,13 @@ unsafe fn handle_deadlock() {
     rustc_data_structures::sync::assert_sync::<tls::ImplicitCtxt<'_, '_>>();
     let icx: &tls::ImplicitCtxt<'_, '_> = &*(context as *const tls::ImplicitCtxt<'_, '_>);
 
-    let session_globals = rustc_span::SESSION_GLOBALS.with(|sg| sg as *const _);
+    let session_globals = rustc_span::with_session_globals(|sg| sg as *const _);
     let session_globals = &*session_globals;
     thread::spawn(move || {
         tls::enter_context(icx, |_| {
-            rustc_span::SESSION_GLOBALS
-                .set(session_globals, || tls::with(|tcx| tcx.queries.deadlock(tcx, &registry)))
+            rustc_span::set_session_globals_then(session_globals, || {
+                tls::with(|tcx| tcx.queries.deadlock(tcx, &registry))
+            })
         });
     });
 }
@@ -203,13 +204,13 @@ pub fn setup_callbacks_and_run_in_thread_pool_with_globals<F: FnOnce() -> R + Se
 
     let with_pool = move |pool: &rayon::ThreadPool| pool.install(f);
 
-    rustc_span::with_session_globals(edition, || {
-        rustc_span::SESSION_GLOBALS.with(|session_globals| {
+    rustc_span::create_session_globals_then(edition, || {
+        rustc_span::with_session_globals(|session_globals| {
             // The main handler runs for each Rayon worker thread and sets up
             // the thread local rustc uses. `session_globals` is captured and set
             // on the new threads.
             let main_handler = move |thread: rayon::ThreadBuilder| {
-                rustc_span::SESSION_GLOBALS.set(session_globals, || {
+                rustc_span::set_session_globals_then(session_globals, || {
                     io::set_output_capture(stderr.clone());
                     thread.run()
                 })