don't print query stack when parallel

Author: SparrowLii

compiler/rustc_query_system/src/query/job.rs

@@ -615,7 +615,7 @@ pub(crate) fn report_cycle<'a, D: DepKind>(
 }
 
 pub fn print_query_stack<Qcx: QueryContext>(
-    qcx: Qcx,
+    _qcx: Qcx,
     mut current_query: Option<QueryJobId>,
     handler: &Handler,
     num_frames: Option<usize>,
@@ -626,12 +626,12 @@ pub fn print_query_stack<Qcx: QueryContext>(
     // state if it was responsible for triggering the panic.
     let mut count_printed = 0;
     let mut count_total = 0;
-    let query_map = qcx.try_collect_active_jobs();
+    #[cfg(not(parallel_compiler))]
+    let query_map = _qcx.try_collect_active_jobs();
 
     if let Some(ref mut file) = file {
         let _ = writeln!(file, "\n\nquery stack during panic:");
-    }
-    while let Some(query) = current_query {
+    }    while let Some(query) = current_query {
         let Some(query_info) = query_map.as_ref().and_then(|map| map.get(&query)) else {
             break;
         };