Rollup merge of #124252 - michaelwoerister:better-forbidden-read-ice, r=oli-obk

Improve ICE message for forbidden dep-graph reads.

The new message mentions the main context that the ICE might occur in and it mentions the query/dep-node that is being read.

cc https://github.com/rust-lang/rust/pull/123781, where this would have been helpful.
This commit is contained in:
Guillaume Gomez 2024-04-22 20:26:00 +02:00 committed by GitHub
commit a60ccc1876
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@ -459,7 +459,8 @@ pub fn read_index(&self, dep_node_index: DepNodeIndex) {
}
TaskDepsRef::Ignore => return,
TaskDepsRef::Forbid => {
panic!("Illegal read of: {dep_node_index:?}")
// Reading is forbidden in this context. ICE with a useful error message.
panic_on_forbidden_read(data, dep_node_index)
}
};
let task_deps = &mut *task_deps;
@ -1366,3 +1367,45 @@ pub(crate) fn print_markframe_trace<D: Deps>(graph: &DepGraph<D>, frame: Option<
eprintln!("end of try_mark_green dep node stack");
}
#[cold]
#[inline(never)]
fn panic_on_forbidden_read<D: Deps>(data: &DepGraphData<D>, dep_node_index: DepNodeIndex) -> ! {
// We have to do an expensive reverse-lookup of the DepNode that
// corresponds to `dep_node_index`, but that's OK since we are about
// to ICE anyway.
let mut dep_node = None;
// First try to find the dep node among those that already existed in the
// previous session
for (prev_index, index) in data.current.prev_index_to_index.lock().iter_enumerated() {
if index == &Some(dep_node_index) {
dep_node = Some(data.previous.index_to_node(prev_index));
break;
}
}
if dep_node.is_none() {
// Try to find it among the new nodes
for shard in data.current.new_node_to_index.lock_shards() {
if let Some((node, _)) = shard.iter().find(|(_, index)| **index == dep_node_index) {
dep_node = Some(*node);
break;
}
}
}
let dep_node = dep_node.map_or_else(
|| format!("with index {:?}", dep_node_index),
|dep_node| format!("`{:?}`", dep_node),
);
panic!(
"Error: trying to record dependency on DepNode {dep_node} in a \
context that does not allow it (e.g. during query deserialization). \
The most common case of recording a dependency on a DepNode `foo` is \
when the correspondng query `foo` is invoked. Invoking queries is not \
allowed as part of loading something from the incremental on-disk cache. \
See <https://github.com/rust-lang/rust/pull/91919>."
)
}