Properly note when query stack is being cut off

Author: compiler-errors

compiler/rustc_driver_impl/src/lib.rs

@@ -1530,9 +1530,9 @@ fn report_ice(
     // If backtraces are enabled, also print the query stack
     let backtrace = env::var_os("RUST_BACKTRACE").is_some_and(|x| &x != "0");
 
-    let num_frames = if backtrace { None } else { Some(2) };
+    let limit_frames = if backtrace { None } else { Some(2) };
 
-    interface::try_print_query_stack(dcx, num_frames, file);
+    interface::try_print_query_stack(dcx, limit_frames, file);
 
     // We don't trust this callback not to panic itself, so run it at the end after we're sure we've
     // printed all the relevant info.

compiler/rustc_interface/src/interface.rs

@@ -533,31 +533,36 @@ pub fn run_compiler<R: Send>(config: Config, f: impl FnOnce(&Compiler) -> R + Se
 
 pub fn try_print_query_stack(
     dcx: DiagCtxtHandle<'_>,
-    num_frames: Option<usize>,
+    limit_frames: Option<usize>,
     file: Option<std::fs::File>,
 ) {
     eprintln!("query stack during panic:");
 
     // Be careful relying on global state here: this code is called from
     // a panic hook, which means that the global `DiagCtxt` may be in a weird
     // state if it was responsible for triggering the panic.
-    let i = ty::tls::with_context_opt(|icx| {
+    let all_frames = ty::tls::with_context_opt(|icx| {
         if let Some(icx) = icx {
             ty::print::with_no_queries!(print_query_stack(
                 QueryCtxt::new(icx.tcx),
                 icx.query,
                 dcx,
-                num_frames,
+                limit_frames,
                 file,
             ))
         } else {
             0
         }
     });
 
-    if num_frames == None || num_frames >= Some(i) {
-        eprintln!("end of query stack");
+    if let Some(limit_frames) = limit_frames
+        && all_frames > limit_frames
+    {
+        eprintln!(
+            "... and {} other queries... use `env RUST_BACKTRACE=1` to see the full query stack",
+            all_frames - limit_frames
+        );
     } else {
-        eprintln!("we're just showing a limited slice of the query stack");
+        eprintln!("end of query stack");
     }
 }

compiler/rustc_query_system/src/query/job.rs

@@ -567,7 +567,7 @@ pub fn print_query_stack<Qcx: QueryContext>(
     qcx: Qcx,
     mut current_query: Option<QueryJobId>,
     dcx: DiagCtxtHandle<'_>,
-    num_frames: Option<usize>,
+    limit_frames: Option<usize>,
     mut file: Option<std::fs::File>,
 ) -> usize {
     // Be careful relying on global state here: this code is called from
@@ -584,7 +584,7 @@ pub fn print_query_stack<Qcx: QueryContext>(
         let Some(query_info) = query_map.get(&query) else {
             break;
         };
-        if Some(count_printed) < num_frames || num_frames.is_none() {
+        if Some(count_printed) < limit_frames || limit_frames.is_none() {
             // Only print to stderr as many stack frames as `num_frames` when present.
             // FIXME: needs translation
             #[allow(rustc::diagnostic_outside_of_impl)]
@@ -615,5 +615,5 @@ pub fn print_query_stack<Qcx: QueryContext>(
     if let Some(ref mut file) = file {
         let _ = writeln!(file, "end of query stack");
     }
-    count_printed
+    count_total
 }