Remove `QueryCtxt` and trait `HasDepContext`#152704

Zalathar · 2026-02-16T10:37:50Z

Follow-up to Big query system cleanups #152636.
Potentially waiting on Remove rustc_query_system #152703 to reduce conflicts.

With the QueryContext trait removed, wrapper struct QueryCtxt no longer serves a purpose and can be replaced with TyCtxt everywhere.

After that, the only obstacle to removing trait HasDepContext is DepGraph::with_task, which uses the trait to allow passing both a TyCtxt and a query vtable through the context argument. But we can achieve the same result by passing the vtable through the other argument instead, in a tuple alongside the query key.

r? nnethercote

Zoxc · 2026-02-16T11:02:03Z

compiler/rustc_middle/src/dep_graph/graph.rs

+        self.assert_dep_node_not_yet_allocated_in_current_session(tcx.sess, &dep_node, || {
+            format!(
+                "forcing query with already existing `DepNode`\n\
+                 - query-key: {task_arg:?}\n\


This won't just print the query key now.

It will print a tuple of (query_name, key), which seems fine.

nnethercote · 2026-02-16T21:29:02Z

compiler/rustc_query_impl/src/execution.rs

    // Delegate to another function to actually execute the query job.
    let (result, dep_node_index) = if INCR {
-        execute_job_incr(query, qcx, qcx.tcx.dep_graph.data().unwrap(), key, dep_node, id)
+        execute_job_incr(query, tcx, tcx.dep_graph.data().unwrap(), key, dep_node, id)


We could now just pass in tcx and get the dep graph data later (in try_load_from_disk_and_cache_in_memory).

That duplicates the unwrap(), so DepGraphData is passed around to indicate incremental is enabled.

I have pushed the call to tcx.dep_graph.data().unwrap() down into execute_job_incr, and incorporated that change into the commit that removes QueryCtxt, because it touches the affected lines anyway.

Pushing the call down any further is not obviously better to me, so I stopped there for now.

compiler/rustc_query_impl/src/lib.rs

nnethercote · 2026-02-16T21:41:21Z

r=me with the nits addressed, and merging should wait for #152703.

Zalathar · 2026-02-17T02:38:34Z

Blocked on Remove rustc_query_system #152703 to minimize potential merge conflicts.

@rustbot blocked

This struct was only wrapping `TyCtxt` in order to implement traits that were removed by RUST-152636. This commit also slightly simplifies the signature of `execute_job_incr`, by having it call `tcx.dep_graph.data()` internally.

The need for a `HasDepContext` impl on tuples can be avoided by passing the query vtable as part of an argument tuple instead.

rustbot · 2026-02-17T06:37:03Z

This PR was rebased onto a different main commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

Zalathar · 2026-02-17T06:39:15Z

Nits addressed, and #152703 has merged.

@rustbot ready
@bors r=nnethercote

rust-bors · 2026-02-17T06:39:18Z

📋 This PR cannot be approved because it currently has the following label: S-blocked.

Zalathar · 2026-02-17T06:39:34Z

@bors r=nnethercote

rust-bors · 2026-02-17T06:39:37Z

📌 Commit 25d5cd2 has been approved by nnethercote

It is now in the queue for this repository.

Remove `QueryCtxt` and trait `HasDepContext` - Follow-up to rust-lang#152636. - Potentially waiting on rust-lang#152703 to reduce conflicts. --- With the `QueryContext` trait removed, wrapper struct `QueryCtxt` no longer serves a purpose and can be replaced with `TyCtxt` everywhere. After that, the only obstacle to removing trait `HasDepContext` is `DepGraph::with_task`, which uses the trait to allow passing both a `TyCtxt` and a query vtable through the context argument. But we can achieve the same result by passing the vtable through the other argument instead, in a tuple alongside the query key. r? nnethercote

Rollup of 6 pull requests Successful merges: - #152609 (Install LLVM DLL in the right place on Windows) - #149904 (`-Znext-solver` Remove the forced ambiguity hack from search graph) - #152704 (Remove `QueryCtxt` and trait `HasDepContext`) - #152746 (remove `#![allow(stable_features)]` from most tests) - #152675 (Improve `VaList` stdlib docs) - #152748 (Update `sysinfo` version to `0.38.2`)

rustbot assigned nnethercote Feb 16, 2026

Zoxc reviewed Feb 16, 2026

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nnethercote approved these changes Feb 16, 2026

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nnethercote added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Feb 16, 2026

Zalathar force-pushed the query-ctxt branch from ac36a07 to 05d7ef2 Compare February 17, 2026 01:25

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Zalathar force-pushed the query-ctxt branch from 05d7ef2 to 6eafec2 Compare February 17, 2026 02:32

rustbot added S-blocked Status: Blocked on something else such as an RFC or other implementation work. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Feb 17, 2026

Zalathar added 3 commits February 17, 2026 17:30

Remove wrapper struct QueryCtxt

fbb34d8

This struct was only wrapping `TyCtxt` in order to implement traits that were removed by RUST-152636. This commit also slightly simplifies the signature of `execute_job_incr`, by having it call `tcx.dep_graph.data()` internally.

Don't use HasDepContext in DepGraph::with_task

db58395

The need for a `HasDepContext` impl on tuples can be avoided by passing the query vtable as part of an argument tuple instead.

Remove unnecessary trait HasDepContext

25d5cd2

Zalathar force-pushed the query-ctxt branch from 6eafec2 to 25d5cd2 Compare February 17, 2026 06:36

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-blocked Status: Blocked on something else such as an RFC or other implementation work. labels Feb 17, 2026

rust-bors bot added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Feb 17, 2026

Zalathar mentioned this pull request Feb 17, 2026

Bring back enum DepKind. #152747

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jdonszelmann mentioned this pull request Feb 17, 2026

Rollup of 6 pull requests #152754

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jdonszelmann mentioned this pull request Feb 17, 2026

Rollup of 6 pull requests #152755

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