Replace two create_default_session_if_not_set_then uses.

With `create_default_session_globals_then`, which is preferable when it
is appropriate.

compiler/rustc_expand/src/tests.rs

@@ -2,7 +2,7 @@ use rustc_ast as ast;
 use rustc_ast::tokenstream::TokenStream;
 use rustc_parse::{new_parser_from_source_str, parser::Parser, source_file_to_stream};
 use rustc_session::parse::ParseSess;
-use rustc_span::create_default_session_if_not_set_then;
+use rustc_span::create_default_session_globals_then;
 use rustc_span::source_map::{FilePathMapping, SourceMap};
 use rustc_span::{BytePos, Span};
 
@@ -181,7 +181,7 @@ impl<T: Write> Write for Shared<T> {
 }
 
 fn test_harness(file_text: &str, span_labels: Vec<SpanLabel>, expected_output: &str) {
-    create_default_session_if_not_set_then(|_| {
+    create_default_session_globals_then(|| {
         let (handler, source_map, output) = create_test_handler();
         source_map.new_source_file(Path::new("test.rs").to_owned().into(), file_text.to_owned());
 

compiler/rustc_hir/src/tests.rs

@@ -2,7 +2,7 @@ use crate::definitions::{DefKey, DefPathData, DisambiguatedDefPathData};
 use rustc_data_structures::stable_hasher::Hash64;
 use rustc_span::def_id::{DefPathHash, StableCrateId};
 use rustc_span::edition::Edition;
-use rustc_span::{create_session_if_not_set_then, Symbol};
+use rustc_span::{create_session_globals_then, Symbol};
 
 #[test]
 fn def_path_hash_depends_on_crate_id() {
@@ -14,7 +14,7 @@ fn def_path_hash_depends_on_crate_id() {
     // the crate by changing the crate disambiguator (e.g. via bumping the
     // crate's version number).
 
-    create_session_if_not_set_then(Edition::Edition2024, |_| {
+    create_session_globals_then(Edition::Edition2024, || {
         let id0 = StableCrateId::new(Symbol::intern("foo"), false, vec!["1".to_string()], "");
         let id1 = StableCrateId::new(Symbol::intern("foo"), false, vec!["2".to_string()], "");