Initial implementation of `FnPtr` trait by carbotaniuman · Pull Request #156176 · rust-lang/rust

carbotaniuman · 2026-05-05T06:20:17Z

This commit is an initial implementation of the FnPtr trait as described in the fn_static tracking issue, which consists of moving the internally unstable core::marker::FnPtr to core::ops::FnPtr, as well as changing the API. Because NonNull is used in the new as_ptr signature, it was also turned into a proper lang item.

Part of fn_static: #148768

rustbot · 2026-05-05T06:20:20Z

The Clippy subtree was changed

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rust-analyzer is developed in its own repository. If possible, consider making this change to rust-lang/rust-analyzer instead.

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Some changes occurred to MIR optimizations

cc @rust-lang/wg-mir-opt

rustbot · 2026-05-05T06:20:23Z

r? @nia-e

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nia-e · 2026-05-07T10:04:03Z

Thanks for the PR! I'll take a proper look asap, but in the meantime could you add some tests for the feature & take a look at the build errors?

rustbot · 2026-05-07T12:50:15Z

This PR changes rustc_public

cc @oli-obk, @celinval, @ouz-a, @makai410

Some changes occurred to the CTFE / Miri interpreter

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Some changes occurred to the CTFE machinery

cc @RalfJung, @oli-obk, @lcnr

nia-e · 2026-05-12T13:27:17Z

 }
+
+/// A type representing a pointer to a function pointer.
+// FIXME: Make this a proper extern type.


What's holding us back from making this an extern type now?
View changes since the review

If I try I get:
error: foreign type has missing stability attribute --> library/core/src/ops/function.rs:318:5 | 318 | pub type Code; | ^^^^^^^^^^^^^
And if I try to put a stability marker on it I get this:
extern "C" { error: `#[unstable]` attribute cannot be used on foreign types --> library/core/src/ops/function.rs:318:5 | 318 | #[unstable(feature = "fn_static", issue = "148768")] | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | = help: `#[unstable]` can be applied to associated consts, associated types, constants, crates, data types, enum variants, extern crates, foreign statics, functions, impl blocks, macro defs, modules, statics, struct fields, trait aliases, traits, type aliases, type parameters, and use statements

we should change our attribute handling to support stabiity attributes on foreign types. please either implement this or open a github issue for this

Don't have the time to implement this right now, but made an issue #158200.

this has been fixed I think, so we can now use extern types here if we need to 🤔

rustbot · 2026-05-12T13:34:01Z

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

…=jackh726 Initial implementation of `FnPtr` trait This commit is an initial implementation of the `FnPtr` trait as described in the `fn_static` tracking issue, which consists of moving the internally unstable `core::marker::FnPtr` to `core::ops::FnPtr`, as well as changing the API. Because `NonNull` is used in the new `as_ptr` signature, it was also turned into a proper lang item. Part of `fn_static`: rust-lang#148768

jhpratt · 2026-08-16T06:26:47Z

@bors r- #161155 (comment)

rust-bors · 2026-08-16T06:26:53Z

This pull request was unapproved.

This PR was contained in a rollup (#161155), which was unapproved.

View changes since this unapproval

rustbot · 2026-08-18T01:24:15Z

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.

This commit is an initial implementation of the `FnPtr` trait as described in the `fn_static` tracking issue, which consists of moving the internally unstable `core::marker::FnPtr` to `core::ops::FnPtr`, as well as changing the API. Because `NonNull` is used in the new `as_ptr` signature, it was also turned into a proper lang item.

jackh726 · 2026-08-18T13:25:50Z

@bors r+

rust-bors · 2026-08-18T13:25:53Z

📌 Commit 5898a39 has been approved by jackh726

It is now in the queue for this repository.

…=jackh726 Initial implementation of `FnPtr` trait This commit is an initial implementation of the `FnPtr` trait as described in the `fn_static` tracking issue, which consists of moving the internally unstable `core::marker::FnPtr` to `core::ops::FnPtr`, as well as changing the API. Because `NonNull` is used in the new `as_ptr` signature, it was also turned into a proper lang item. Part of `fn_static`: rust-lang#148768

…uwer Rollup of 8 pull requests Successful merges: - #154210 (fix: fix the capture behavior of `if let` in closures) - #156176 (Initial implementation of `FnPtr` trait) - #160767 (Unify E0117 foreign-trait label for ADT/primitive types with existing Slice/Array/Tuple handling) - #160489 (Adding diagnostic item markers for multiple fs functions and structs) - #161220 (bootstrap: Allow `./x fix --allow-dirty`) - #161291 (Rename `ProjectionPredicate` and `TraitPredicate`) - #161296 (Enable overflow checks in `rustc_thread_pool`) - #161304 (Rename test so it matches the issue)

…=jackh726 Initial implementation of `FnPtr` trait This commit is an initial implementation of the `FnPtr` trait as described in the `fn_static` tracking issue, which consists of moving the internally unstable `core::marker::FnPtr` to `core::ops::FnPtr`, as well as changing the API. Because `NonNull` is used in the new `as_ptr` signature, it was also turned into a proper lang item. Part of `fn_static`: rust-lang#148768

Rollup of 18 pull requests Successful merges: - #154210 (fix: fix the capture behavior of `if let` in closures) - #156176 (Initial implementation of `FnPtr` trait) - #160767 (Unify E0117 foreign-trait label for ADT/primitive types with existing Slice/Array/Tuple handling) - #161297 (std: use UNIX's `Instant` and `SystemTime` on Hermit) - #160489 (Adding diagnostic item markers for multiple fs functions and structs) - #160643 (Require windowed (and exception) for Xtensa ABI) - #161088 (suppress projection errors already covered by a trait error) - #161114 (Remove fields from TypeKind: Struct, Enum, Union and Tuple) - #161115 (Assorted allocator nitpicks) - #161220 (bootstrap: Allow `./x fix --allow-dirty`) - #161296 (Enable overflow checks in `rustc_thread_pool`) - #161298 (remove rustc_error_messages dependency) - #161304 (Rename test so it matches the issue) - #161309 (`allow(non_camel_case_types)` in `minicore.rs`) - #161315 (Relax codgen test variable regex) - #161318 (Doc: clarify how `Read::bytes` handling Interrupted errors) - #161321 (Update books) - #161335 ([compiletest] Use the correct rustc lib directory for query_rustc_output)

Rollup merge of #156176 - carbotaniuman:fn-ptr-trait-impl, r=jackh726 Initial implementation of `FnPtr` trait This commit is an initial implementation of the `FnPtr` trait as described in the `fn_static` tracking issue, which consists of moving the internally unstable `core::marker::FnPtr` to `core::ops::FnPtr`, as well as changing the API. Because `NonNull` is used in the new `as_ptr` signature, it was also turned into a proper lang item. Part of `fn_static`: #148768

Rollup of 18 pull requests Successful merges: - rust-lang/rust#154210 (fix: fix the capture behavior of `if let` in closures) - rust-lang/rust#156176 (Initial implementation of `FnPtr` trait) - rust-lang/rust#160767 (Unify E0117 foreign-trait label for ADT/primitive types with existing Slice/Array/Tuple handling) - rust-lang/rust#161297 (std: use UNIX's `Instant` and `SystemTime` on Hermit) - rust-lang/rust#160489 (Adding diagnostic item markers for multiple fs functions and structs) - rust-lang/rust#160643 (Require windowed (and exception) for Xtensa ABI) - rust-lang/rust#161088 (suppress projection errors already covered by a trait error) - rust-lang/rust#161114 (Remove fields from TypeKind: Struct, Enum, Union and Tuple) - rust-lang/rust#161115 (Assorted allocator nitpicks) - rust-lang/rust#161220 (bootstrap: Allow `./x fix --allow-dirty`) - rust-lang/rust#161296 (Enable overflow checks in `rustc_thread_pool`) - rust-lang/rust#161298 (remove rustc_error_messages dependency) - rust-lang/rust#161304 (Rename test so it matches the issue) - rust-lang/rust#161309 (`allow(non_camel_case_types)` in `minicore.rs`) - rust-lang/rust#161315 (Relax codgen test variable regex) - rust-lang/rust#161318 (Doc: clarify how `Read::bytes` handling Interrupted errors) - rust-lang/rust#161321 (Update books) - rust-lang/rust#161335 ([compiletest] Use the correct rustc lib directory for query_rustc_output)

rustbot assigned nia-e May 5, 2026