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Auto merge of #108820 - cjgillot:ensure-on-disk, r=oli-obk

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Ensure value is on the on-disk cache before returning from `ensure()`.

The current logic for `ensure()` a query just checks that the node is green in the dependency graph.
However, a lot of places use `ensure()` to prevent the query from being called later. This is the case before stealing a query result.

If the query is actually green but the value is not available in the on-disk cache, `ensure` would return, but a subsequent call to the full query would run the code, and attempt to read from a stolen value.

This PR conforms the query system to the usage by checking whether the queried value is loadable from disk before returning.

Sadly, I can't manage to craft a proper test...

Should fix all instances of "attempted to read from stolen value".
This commit is contained in:
bors 2023-03-12 14:00:28 +00:00
commit f41927f309
10 changed files with 116 additions and 30 deletions
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11
compiler/rustc_mir_build/src/build/mod.rs
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@ -48,17 +48,14 @@ pub(crate) fn mir_built(
/// Construct the MIR for a given `DefId`.
fn mir_build(tcx: TyCtxt<'_>, def: ty::WithOptConstParam<LocalDefId>) -> Body<'_> {
// Ensure unsafeck and abstract const building is ran before we steal the THIR.
// We can't use `ensure()` for `thir_abstract_const` as it doesn't compute the query
// if inputs are green. This can cause ICEs when calling `thir_abstract_const` after
// THIR has been stolen if we haven't computed this query yet.
match def {
ty::WithOptConstParam { did, const_param_did: Some(const_param_did) } => {
tcx.ensure().thir_check_unsafety_for_const_arg((did, const_param_did));
drop(tcx.thir_abstract_const_of_const_arg((did, const_param_did)));
tcx.ensure_with_value().thir_check_unsafety_for_const_arg((did, const_param_did));
tcx.ensure_with_value().thir_abstract_const_of_const_arg((did, const_param_did));
}
ty::WithOptConstParam { did, const_param_did: None } => {
tcx.ensure().thir_check_unsafety(did);
drop(tcx.thir_abstract_const(did));
tcx.ensure_with_value().thir_check_unsafety(did);
tcx.ensure_with_value().thir_abstract_const(did);
}
}