Rollup merge of #108297 - chenyukang:yukang/delim-error-exit, r=petrochenkov

Exit when there are unmatched delims to avoid noisy diagnostics

From https://github.com/rust-lang/rust/pull/104012#issuecomment-1311764832
r? ``@petrochenkov``

compiler/rustc_expand/src/tests.rs

@@ -43,7 +43,6 @@ pub(crate) fn string_to_stream(source_str: String) -> TokenStream {
         ps.source_map().new_source_file(PathBuf::from("bogofile").into(), source_str),
         None,
     )
-    .0
 }
 
 /// Parses a string, returns a crate.