bjoernager/rust
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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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5
compiler/rustc_ast_lowering/src/lib.rs
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@ -435,8 +435,9 @@ fn compute_hir_hash(
pub fn lower_to_hir(tcx: TyCtxt<'_>, (): ()) -> hir::Crate<'_> {
let sess = tcx.sess;
tcx.ensure().output_filenames(());
let _ = tcx.early_lint_checks(()); // Borrows `resolver_for_lowering`.
// Queries that borrow `resolver_for_lowering`.
tcx.ensure_with_value().output_filenames(());
tcx.ensure_with_value().early_lint_checks(());
let (mut resolver, krate) = tcx.resolver_for_lowering(()).steal();
let ast_index = index_crate(&resolver.node_id_to_def_id, &krate);