Support pointers in type reflection #151119

BD103 · 2026-01-14T15:33:30Z

Tracking issue: #146922

This PR adds support for inspecting pointers *const T and *mut T through type reflection. It does so by adding the new Pointer struct + variant:

pub struct Pointer {
    /// The type of the value being pointed to.
    pub ty: TypeId,
    /// Whether this pointer is mutable or not.
    pub mutable: bool,
}

This can be gathered using Type::of, for example:

match const { Type::of::<*const u8>() }.kind {
    TypeKind::Pointer(pointer) => {
        assert_eq!(pointer.ty, TypeId::of::<u8>());
        assert!(!pointer.mutable);
    }
    _ => unreachable!(),
}

rustbot · 2026-01-14T15:33:34Z

Some changes occurred to the CTFE machinery

cc @RalfJung, @oli-obk, @lcnr

The reflection data structures are tied exactly to the implementation
in the compiler. Make sure to also adjust rustc_const_eval/src/const_eval/type_info.rs

cc @oli-obk

rustbot · 2026-01-14T15:33:36Z

r? @JonathanBrouwer

rustbot has assigned @JonathanBrouwer.
They will have a look at your PR within the next two weeks and either review your PR or reassign to another reviewer.

Use r? to explicitly pick a reviewer

library/core/src/mem/type_info.rs

BD103 · 2026-01-14T15:40:35Z

r? @oli-obk

rustbot · 2026-01-14T15:40:39Z

oli-obk is not on the review rotation at the moment.
They may take a while to respond.

compiler/rustc_const_eval/src/const_eval/type_info.rs

library/core/src/mem/type_info.rs

feat: Support references in reflection type info Tracking issue: rust-lang#146922 `#![feature(type_info)]` Based on rust-lang#151119 implementation for pointers for consistency r? oli-obk

Rollup merge of #151222 - reflect-references, r=oli-obk feat: Support references in reflection type info Tracking issue: #146922 `#![feature(type_info)]` Based on #151119 implementation for pointers for consistency r? oli-obk

oli-obk · 2026-01-18T17:50:22Z

Needs a rebase

rustbot · 2026-01-19T03:54:58Z

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.

oli-obk · 2026-01-19T14:59:09Z

tests/ui/reflection/dump.rs

        &Unsized, &str, &[u8],
        str, [u8],
        &u8, &mut u8,
+        *const u8, *mut u8,


Since we encountered problems with dumps in other PRs with these dumps let's not add more here. You already added assert tests, those are sufficient

Yeah, good call. Is there still a benefit in dump.rs, or can it be deleted? (In a follow-up PR.)

Should make sure there is sufficient other testing for the existing cases, but yea, that seems like the best

oli-obk · 2026-01-19T17:02:06Z

@bors r+ rollup

rust-bors · 2026-01-19T17:02:09Z

📌 Commit 976cea3 has been approved by oli-obk

It is now in the queue for this repository.

@ghost

…uwer Rollup of 15 pull requests Successful merges: - #148623 (Ignore `#[doc(hidden)]` items when computing trimmed paths for printing) - #150550 (Miscellaneous cleanups to borrowck related code) - #150879 (Remove the diagnostic lints) - #150895 (rustc_errors: Add (heuristic) Syntax Highlighting for `rustc --explain`) - #150987 (remote-test-server: Fix header in batch mode) - #151004 (std: implement `sleep_until` on Apple platforms) - #151045 (Simplify some literal-value negations with `u128::wrapping_neg`) - #151119 (Support pointers in type reflection) - #151171 (Do not recover from `Trait()` if generic list is unterminated) - #151231 (HIR typeck cleanup: clarify and re-style `check_expr_unop`) - #151249 (Parse ident with allowing recovery when trying to diagnose) - #151295 (THIR patterns: Use `ty::Value` in more places throughout `const_to_pat`) - #151326 (Remove `DiagMessage::Translated` in favour of `DiagMessage::Str`) - #151361 (add test for issue 61463) - #151371 (Add `S-blocked` to `labels_blocking_approval`) r? @ghost

Rollup merge of #151119 - reflect-pointers, r=oli-obk Support pointers in type reflection Tracking issue: #146922 This PR adds support for inspecting pointers `*const T` and `*mut T` through type reflection. It does so by adding the new `Pointer` struct + variant: ```rust pub struct Pointer { /// The type of the value being pointed to. pub ty: TypeId, /// Whether this pointer is mutable or not. pub mutable: bool, } ``` This can be gathered using `Type::of`, for example: ```rust match const { Type::of::<*const u8>() }.kind { TypeKind::Pointer(pointer) => { assert_eq!(pointer.ty, TypeId::of::<u8>()); assert!(!pointer.mutable); } _ => unreachable!(), } ```

@ghost

…uwer Rollup of 15 pull requests Successful merges: - rust-lang/rust#148623 (Ignore `#[doc(hidden)]` items when computing trimmed paths for printing) - rust-lang/rust#150550 (Miscellaneous cleanups to borrowck related code) - rust-lang/rust#150879 (Remove the diagnostic lints) - rust-lang/rust#150895 (rustc_errors: Add (heuristic) Syntax Highlighting for `rustc --explain`) - rust-lang/rust#150987 (remote-test-server: Fix header in batch mode) - rust-lang/rust#151004 (std: implement `sleep_until` on Apple platforms) - rust-lang/rust#151045 (Simplify some literal-value negations with `u128::wrapping_neg`) - rust-lang/rust#151119 (Support pointers in type reflection) - rust-lang/rust#151171 (Do not recover from `Trait()` if generic list is unterminated) - rust-lang/rust#151231 (HIR typeck cleanup: clarify and re-style `check_expr_unop`) - rust-lang/rust#151249 (Parse ident with allowing recovery when trying to diagnose) - rust-lang/rust#151295 (THIR patterns: Use `ty::Value` in more places throughout `const_to_pat`) - rust-lang/rust#151326 (Remove `DiagMessage::Translated` in favour of `DiagMessage::Str`) - rust-lang/rust#151361 (add test for issue 61463) - rust-lang/rust#151371 (Add `S-blocked` to `labels_blocking_approval`) r? @ghost

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BD103 commented Jan 14, 2026

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BD103 force-pushed the reflect-pointers branch from e298be8 to c0a4f8c Compare January 16, 2026 15:33

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clubby789 mentioned this pull request Jan 16, 2026

feat: Support references in reflection type info #151222

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BD103 force-pushed the reflect-pointers branch from 2a7b6c5 to f3afe60 Compare January 19, 2026 03:54

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feat: support pointers in type info

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Rollup of 15 pull requests #151381

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rust-bors bot merged commit 25e6f5c into rust-lang:main Jan 20, 2026
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BD103 deleted the reflect-pointers branch January 20, 2026 20:15

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