Remove `impl IntoQueryParam<P> for &'a P`. by nnethercote · Pull Request #152879 · rust-lang/rust

nnethercote · 2026-02-20T01:51:31Z

IntoQueryParam is a trait that lets query callers be a bit sloppy with the passed-in key.

Types similar to DefId will be auto-converted to DefId. Likewise for LocalDefId.
Reference types will be auto-derefed.

The auto-conversion is genuinely useful; the auto-derefing much less so. In practice it's only used for passing &DefId to queries that accept DefId, which is an anti-pattern because DefId is marked with #[rustc_pass_by_value].

This commit removes the auto-deref impl and makes the necessary sigil adjustments. (I generally avoid using * to deref manually at call sites, preferring to deref via & in patterns or via * in match expressions. Mostly because that way a single deref often covers multiple call sites.)

r? @cjgillot

rustbot · 2026-02-20T01:51:34Z

Some changes occurred to the CTFE machinery

cc @RalfJung, @oli-obk, @lcnr

Some changes occurred to constck

cc @fee1-dead

The Miri subtree was changed

cc @rust-lang/miri

HIR ty lowering was modified

cc @fmease

Some changes occurred to the CTFE / Miri interpreter

cc @rust-lang/miri, @RalfJung, @oli-obk, @lcnr

Some changes occurred in src/tools/clippy

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Some changes occurred to MIR optimizations

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oli-obk

I don't feel like the motivation is strong, it's a nice convenience feature, but considering all the other dereffing we do not really important

View changes since this review

compiler/rustc_hir_analysis/src/collect/resolve_bound_vars.rs

src/tools/clippy/clippy_utils/src/lib.rs

rustbot · 2026-02-20T13:50:56Z

Reminder, once the PR becomes ready for a review, use @rustbot ready.

nnethercote · 2026-02-20T21:51:00Z

Thanks for the review! I have fixed the two nits.

I don't feel like the motivation is strong

Let me explain why I did this. I'm on a ruthless drive to reduce complexity in the query system because I think it's a big problem. IntoQueryParam isn't like a lot of other traits because of its location. To understand it you also need some understanding of the rustc_queries! proc macro and the define_callbacks! declarative macro. That's two layers of complex macros. I think removing anything from within those two layers of macros has outsized positive effects.

I would actually like to remove IntoQueryParam entirely. (Pop quiz: do you know why define_callbacks! uses $($K:tt)* instead of the more obvious $K:ty? It's related.) But that would be a much more invasive change. Removing the auto-derefing eliminates a non-trivial wrinkle from within the two layers of macros, at the cost of some sigil fiddling of the variety we are all familiar with. I think that's worthwhile.

oli-obk · 2026-02-21T06:16:06Z

@bors r+

rust-bors · 2026-02-21T06:16:10Z

📌 Commit fb4258c has been approved by oli-obk

It is now in the queue for this repository.

@cjgillot

…-ref-P, r=oli-obk Remove `impl IntoQueryParam<P> for &'a P`. `IntoQueryParam` is a trait that lets query callers be a bit sloppy with the passed-in key. - Types similar to `DefId` will be auto-converted to `DefId`. Likewise for `LocalDefId`. - Reference types will be auto-derefed. The auto-conversion is genuinely useful; the auto-derefing much less so. In practice it's only used for passing `&DefId` to queries that accept `DefId`, which is an anti-pattern because `DefId` is marked with `#[rustc_pass_by_value]`. This commit removes the auto-deref impl and makes the necessary sigil adjustments. (I generally avoid using `*` to deref manually at call sites, preferring to deref via `&` in patterns or via `*` in match expressions. Mostly because that way a single deref often covers multiple call sites.) r? @cjgillot

matthiaskrgr · 2026-02-21T12:03:09Z

@bors r-
may neeed rebase #152932 (comment)

`IntoQueryParam` is a trait that lets query callers be a bit sloppy with the passed-in key. - Types similar to `DefId` will be auto-converted to `DefId`. Likewise for `LocalDefId`. - Reference types will be auto-derefed. The auto-conversion is genuinely useful; the auto-derefing much less so. In practice it's only used for passing `&DefId` to queries that accept `DefId`, which is an anti-pattern because `DefId` is marked with `#[rustc_pass_by_value]`. This commit removes the auto-deref impl and makes the necessary sigil adjustments. (I generally avoid using `*` to deref manually at call sites, preferring to deref via `&` in patterns or via `*` in match expressions. Mostly because that way a single deref often covers multiple call sites.)

rustbot · 2026-02-22T06:59:05Z

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.

nnethercote · 2026-02-22T06:59:17Z

I rebased.

@bors r=oli-obk rollup

rust-bors · 2026-02-22T06:59:19Z

📌 Commit a3d5908 has been approved by oli-obk

It is now in the queue for this repository.

nnethercote · 2026-02-22T07:31:31Z

(Apologies: I wrote a couple of comments here that were intended for #152958.)

@cjgillot

…-ref-P, r=oli-obk Remove `impl IntoQueryParam<P> for &'a P`. `IntoQueryParam` is a trait that lets query callers be a bit sloppy with the passed-in key. - Types similar to `DefId` will be auto-converted to `DefId`. Likewise for `LocalDefId`. - Reference types will be auto-derefed. The auto-conversion is genuinely useful; the auto-derefing much less so. In practice it's only used for passing `&DefId` to queries that accept `DefId`, which is an anti-pattern because `DefId` is marked with `#[rustc_pass_by_value]`. This commit removes the auto-deref impl and makes the necessary sigil adjustments. (I generally avoid using `*` to deref manually at call sites, preferring to deref via `&` in patterns or via `*` in match expressions. Mostly because that way a single deref often covers multiple call sites.) r? @cjgillot

Rollup of 15 pull requests Successful merges: - #150468 (rustc_target: callconv: powerpc64: Use the ABI set in target options instead of guessing) - #151628 (Fix ICE in const eval of packed SIMD types with non-power-of-two element counts) - #151871 (don't use env with infer vars) - #152591 (Simplify internals of `{Rc,Arc}::default`) - #152865 (Fixed ByteStr not padding within its Display trait when no specific alignment is mentioned) - #152908 (Enable rust.remap-debuginfo in the dist profile) - #147859 (reduce the amount of panics in `{TokenStream, Literal}::from_str` calls) - #152705 (Test(lib/win/proc): Skip `raw_attributes` doctest under Win7) - #152767 (fix typo in `carryless_mul` macro invocation) - #152837 (fix(codegen): Use `body_codegen_attrs` For Caller In `adjust_target_feature_sig`) - #152871 (Fix warnings in rs{begin,end}.rs files) - #152879 (Remove `impl IntoQueryParam<P> for &'a P`.) - #152933 (Start migration for `LintDiagnostic` items by adding API and migrating `LinkerOutput` lint) - #152937 (remove unneeded reboxing) - #152953 (Fix typo in armv7a-vex-v5.md)

rustbot assigned cjgillot Feb 20, 2026

oli-obk requested changes Feb 20, 2026

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nnethercote force-pushed the rm-impl-IntoQueryParam-ref-P branch from 89a8e28 to 5e3d666 Compare February 20, 2026 21:47

nnethercote force-pushed the rm-impl-IntoQueryParam-ref-P branch from 5e3d666 to fb4258c Compare February 20, 2026 22:05

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matthiaskrgr mentioned this pull request Feb 21, 2026

Rollup of 7 pull requests #152932

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nnethercote force-pushed the rm-impl-IntoQueryParam-ref-P branch from fb4258c to a3d5908 Compare February 22, 2026 06:59

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jhpratt mentioned this pull request Feb 22, 2026

Rollup of 15 pull requests #152960

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