Rework SESSION_GLOBALS API to prevent overwriting it

3 files changed, 11 insertions, 6 deletions

diff --git a/src/tools/clippy/clippy_lints/src/doc.rs b/src/tools/clippy/clippy_lints/src/doc.rs
index 4e164d33a05..d6e3e92fc5e 100644
--- a/src/tools/clippy/clippy_lints/src/doc.rs
+++ b/src/tools/clippy/clippy_lints/src/doc.rs
@@ -26,6 +26,7 @@ use rustc_span::source_map::{BytePos, FilePathMapping, MultiSpan, SourceMap, Spa
 use rustc_span::{sym, FileName, Pos};
 use std::io;
 use std::ops::Range;
+use std::thread;
 use url::Url;
 
 declare_clippy_lint! {
@@ -584,10 +585,10 @@ fn get_current_span(spans: &[(usize, Span)], idx: usize) -> (usize, Span) {
 }
 
 fn check_code(cx: &LateContext<'_>, text: &str, edition: Edition, span: Span) {
-    fn has_needless_main(code: &str, edition: Edition) -> bool {
+    fn has_needless_main(code: String, edition: Edition) -> bool {
         rustc_driver::catch_fatal_errors(|| {
-            rustc_span::with_session_globals(edition, || {
-                let filename = FileName::anon_source_code(code);
+            rustc_span::create_session_globals_then(edition, || {
+                let filename = FileName::anon_source_code(&code);
 
                 let sm = Lrc::new(SourceMap::new(FilePathMapping::empty()));
                 let emitter = EmitterWriter::new(box io::sink(), None, false, false, false, None, false);
@@ -649,7 +650,10 @@ fn check_code(cx: &LateContext<'_>, text: &str, edition: Edition, span: Span) {
         .unwrap_or_default()
     }
 
-    if has_needless_main(text, edition) {
+    // Because of the global session, we need to create a new session in a different thread with
+    // the edition we need.
+    let text = text.to_owned();
+    if thread::spawn(move || has_needless_main(text, edition)).join().expect("thread::spawn failed") {
         span_lint(cx, NEEDLESS_DOCTEST_MAIN, span, "needless `fn main` in doctest");
     }
 }
diff --git a/src/tools/error_index_generator/main.rs b/src/tools/error_index_generator/main.rs
index e3700136aca..01a3fc812b2 100644
--- a/src/tools/error_index_generator/main.rs
+++ b/src/tools/error_index_generator/main.rs
@@ -284,7 +284,8 @@ fn parse_args() -> (OutputFormat, PathBuf) {
 fn main() {
     rustc_driver::init_env_logger("RUST_LOG");
     let (format, dst) = parse_args();
-    let result = rustc_span::with_default_session_globals(move || main_with_result(format, &dst));
+    let result =
+        rustc_span::create_default_session_globals_then(move || main_with_result(format, &dst));
     if let Err(e) = result {
         panic!("{}", e.to_string());
     }
diff --git a/src/tools/rustfmt/src/formatting.rs b/src/tools/rustfmt/src/formatting.rs
index b69ecdc5cb8..e0403574eeb 100644
--- a/src/tools/rustfmt/src/formatting.rs
+++ b/src/tools/rustfmt/src/formatting.rs
@@ -34,7 +34,7 @@ impl<'b, T: Write + 'b> Session<'b, T> {
             return Err(ErrorKind::VersionMismatch);
         }
 
-        rustc_span::with_session_globals(self.config.edition().into(), || {
+        rustc_span::create_session_if_not_set_then(self.config.edition().into(), |_| {
             if self.config.disable_all_formatting() {
                 // When the input is from stdin, echo back the input.
                 if let Input::Text(ref buf) = input {