validate `#[link_name = "..."]` & `#[link(name = "...")]` parameters by folkertdev · Pull Request #155817 · rust-lang/rust

folkertdev · 2026-04-26T11:04:17Z

specifically, do not allow NULL bytes and the empty string in #[link_name = "..."] and #[link(name = "...")].

Like some of the others I think this formally needs to be looked at by T-lang because these errors would not show up if not linking.

The LLVM erorr on #[linke_name = "\0"] is emitted here, it is not e.g. target-specific.

https://github.com/llvm/llvm-project/blob/d593279c0b2891f0b0c8af3f70a1a0383b4ad1b5/llvm/lib/IR/Value.cpp#L336-L342

On #[link(name = "")] we already error today. A NULL byte in #[link(name = "\0")] is caught by the linker (https://godbolt.org/z/vnz9sYbPs), using #[link_name = ""] makes LLVM generate a name (https://godbolt.org/z/1hWEo4cxf) which is not useful and likely to cause linker errors.

r? jdonszelmann

rustbot · 2026-04-26T11:04:20Z

Some changes occurred in compiler/rustc_attr_parsing

cc @jdonszelmann, @JonathanBrouwer

mejrs

r? me

r=me on the implementation, pending lang approval

View changes since this review

folkertdev · 2026-04-26T11:48:16Z

    #[link_name = "@GLIBC_2.2.5"]
    pub safe fn exit_1(status: i32) -> !; //~ ERROR link name must be well-formed if link kind is `raw-dylib`


I think we should move these errors to rustc_attr_parsing too, for consistency and so that the ranges can actually point to the attribute instead of the item.

That's not something T-lang needs to worry about though, so probably best done separately.

cc @usamoi (this test was added by #144221)

View changes since the review

specifically, do not allow NULL bytes and the empty string

traviscross · 2026-04-29T15:14:26Z

Thanks @folkertdev for cleaning these up.

@rfcbot fcp merge lang

rust-rfcbot · 2026-04-29T15:14:28Z

Team member @traviscross has proposed to merge this. The next step is review by the rest of the tagged team members:

No concerns currently listed.

Once a majority of reviewers approve (and at most 2 approvals are outstanding), this will enter its final comment period. If you spot a major issue that hasn't been raised at any point in this process, please speak up!

cc @rust-lang/lang-advisors: FCP proposed for lang, please feel free to register concerns.
See this document for info about what commands tagged team members can give me.

rust-rfcbot · 2026-04-29T15:16:29Z

🔔 This is now entering its final comment period, as per the review above. 🔔

rust-rfcbot · 2026-05-09T15:19:35Z

The final comment period, with a disposition to merge, as per the review above, is now complete.

As the automated representative of the governance process, I would like to thank the author for their work and everyone else who contributed.

folkertdev · 2026-05-09T15:41:50Z

@bors r=mejrs rollup

rust-bors · 2026-05-09T15:41:53Z

📋 This PR cannot be approved because it currently has the following label: S-waiting-on-t-lang.

folkertdev · 2026-05-09T15:42:26Z

@bors r=mejrs rollup

rust-bors · 2026-05-09T15:42:29Z

📌 Commit c08b9ab has been approved by mejrs

It is now in the queue for this repository.

…=mejrs validate `#[link_name = "..."]` & `#[link(name = "...")]` parameters fixes rust-lang#155776 fixes rust-lang#155484 specifically, do not allow NULL bytes and the empty string in `#[link_name = "..."]` and `#[link(name = "...")]`. Like some of the others I think this formally needs to be looked at by T-lang because these errors would not show up if not linking. The LLVM erorr on `#[linke_name = "\0"]` is emitted here, it is not e.g. target-specific. https://github.com/llvm/llvm-project/blob/d593279c0b2891f0b0c8af3f70a1a0383b4ad1b5/llvm/lib/IR/Value.cpp#L336-L342 On `#[link(name = "")]` we already error today. A NULL byte in `#[link(name = "\0")]` is caught by the linker (https://godbolt.org/z/vnz9sYbPs), using `#[link_name = ""]` makes LLVM generate a name (https://godbolt.org/z/1hWEo4cxf) which is not useful and likely to cause linker errors. r? jdonszelmann

Rollup of 5 pull requests Successful merges: - #148214 (Consider `Result<T, Uninhabited>` and `ControlFlow<Uninhabited, T>` to be equivalent to `T` for must use lint) - #149362 (Add Command::get_resolved_envs) - #155188 (Add regression test for issue 144329) - #155515 (error on empty `export_name`) - #155817 (validate `#[link_name = "..."]` & `#[link(name = "...")]` parameters)

…=mejrs validate `#[link_name = "..."]` & `#[link(name = "...")]` parameters fixes rust-lang#155776 fixes rust-lang#155484 specifically, do not allow NULL bytes and the empty string in `#[link_name = "..."]` and `#[link(name = "...")]`. Like some of the others I think this formally needs to be looked at by T-lang because these errors would not show up if not linking. The LLVM erorr on `#[linke_name = "\0"]` is emitted here, it is not e.g. target-specific. https://github.com/llvm/llvm-project/blob/d593279c0b2891f0b0c8af3f70a1a0383b4ad1b5/llvm/lib/IR/Value.cpp#L336-L342 On `#[link(name = "")]` we already error today. A NULL byte in `#[link(name = "\0")]` is caught by the linker (https://godbolt.org/z/vnz9sYbPs), using `#[link_name = ""]` makes LLVM generate a name (https://godbolt.org/z/1hWEo4cxf) which is not useful and likely to cause linker errors. r? jdonszelmann

…uwer Rollup of 10 pull requests Successful merges: - #148214 (Consider `Result<T, Uninhabited>` and `ControlFlow<Uninhabited, T>` to be equivalent to `T` for must use lint) - #149362 (Add Command::get_resolved_envs) - #155705 (Add `str::word_to_titlecase()` to `alloc`) - #155970 (Add mention of sendfile(2) and splice(2) to fs::copy() documentation.) - #156006 (Update a bunch of bootstrap dependencies to remove windows-target) - #155188 (Add regression test for issue 144329) - #155515 (error on empty `export_name`) - #155817 (validate `#[link_name = "..."]` & `#[link(name = "...")]` parameters) - #156107 (remove turbofish notation + use None / Some instead of Option:: (in match documentation)) - #156133 (mark some panicking methods around Duration as track_caller)

Rollup of 11 pull requests Successful merges: - #149362 (Add Command::get_resolved_envs) - #155705 (Add `str::word_to_titlecase()` to `alloc`) - #155970 (Add mention of sendfile(2) and splice(2) to fs::copy() documentation.) - #156006 (Update a bunch of bootstrap dependencies to remove windows-target) - #156169 (Change `SwitchInt` handling in dataflow analysis.) - #155188 (Add regression test for issue 144329) - #155515 (error on empty `export_name`) - #155817 (validate `#[link_name = "..."]` & `#[link(name = "...")]` parameters) - #156107 (remove turbofish notation + use None / Some instead of Option:: (in match documentation)) - #156133 (mark some panicking methods around Duration as track_caller) - #156363 (`rustc_attr_parsing`: add `AcceptContext::expect_string_literal`)

Rollup merge of #155817 - folkertdev:link-name-null-empty, r=mejrs validate `#[link_name = "..."]` & `#[link(name = "...")]` parameters fixes #155776 fixes #155484 specifically, do not allow NULL bytes and the empty string in `#[link_name = "..."]` and `#[link(name = "...")]`. Like some of the others I think this formally needs to be looked at by T-lang because these errors would not show up if not linking. The LLVM erorr on `#[linke_name = "\0"]` is emitted here, it is not e.g. target-specific. https://github.com/llvm/llvm-project/blob/d593279c0b2891f0b0c8af3f70a1a0383b4ad1b5/llvm/lib/IR/Value.cpp#L336-L342 On `#[link(name = "")]` we already error today. A NULL byte in `#[link(name = "\0")]` is caught by the linker (https://godbolt.org/z/vnz9sYbPs), using `#[link_name = ""]` makes LLVM generate a name (https://godbolt.org/z/1hWEo4cxf) which is not useful and likely to cause linker errors. r? jdonszelmann

rust-lang/rust#155817 added some restrictions on the symbol name in the `link_name` attribute. The name cannot be empty or contain null bytes.

rustbot added A-attributes Area: Attributes (`#[…]`, `#![…]`) S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Apr 26, 2026

rustbot assigned jdonszelmann Apr 26, 2026

folkertdev changed the title ~~validate #[link_name = "..."] parameter~~ validate #[link_name = "..."] & #[link(name = "...")] parameters Apr 26, 2026

mejrs approved these changes Apr 26, 2026

View reviewed changes

Comment thread compiler/rustc_attr_parsing/src/attributes/link_attrs.rs Outdated

rustbot assigned mejrs and unassigned jdonszelmann Apr 26, 2026

This comment has been minimized.

Sign in to view

folkertdev added I-lang-nominated Nominated for discussion during a lang team meeting. S-waiting-on-t-lang Status: Awaiting decision from T-lang labels Apr 26, 2026

folkertdev force-pushed the link-name-null-empty branch from b94ed3f to 2ffa233 Compare April 26, 2026 11:45

folkertdev commented Apr 26, 2026

View reviewed changes

folkertdev force-pushed the link-name-null-empty branch from 2ffa233 to 4338dfc Compare April 26, 2026 17:17

This comment has been minimized.

Sign in to view

folkertdev force-pushed the link-name-null-empty branch from 4338dfc to 5a5ae4c Compare April 26, 2026 17:26

This comment has been minimized.

Sign in to view

validate link name parameter

c08b9ab

specifically, do not allow NULL bytes and the empty string

folkertdev force-pushed the link-name-null-empty branch from 5a5ae4c to c08b9ab Compare April 26, 2026 17:36

traviscross added P-lang-drag-1 Lang team prioritization drag level 1. https://rust-lang.zulipchat.com/#narrow/channel/410516-t-lang I-lang-radar Items that are on lang's radar and will need eventual work or consideration. T-lang Relevant to the language team labels Apr 29, 2026

rust-rfcbot removed the final-comment-period In the final comment period and will be merged soon unless new substantive objections are raised. label May 9, 2026

rust-rfcbot added the to-announce Announce this issue on triage meeting label May 9, 2026

rustbot mentioned this pull request May 9, 2026

Tracking issue for release notes of #155817: validate #[link_name = "..."] & #[link(name = "...")] parameters #156364

Open

folkertdev removed the S-waiting-on-t-lang Status: Awaiting decision from T-lang label May 9, 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 May 9, 2026

matthiaskrgr mentioned this pull request May 9, 2026

Rollup of 5 pull requests #156369

Closed

JonathanBrouwer mentioned this pull request May 9, 2026

Rollup of 11 pull requests #156371

Closed

JonathanBrouwer mentioned this pull request May 9, 2026

Rollup of 10 pull requests #156374

Closed

matthiaskrgr mentioned this pull request May 10, 2026

Rollup of 11 pull requests #156378

Merged

rust-bors Bot merged commit 99abbd6 into rust-lang:main May 10, 2026
11 checks passed

rustbot added this to the 1.97.0 milestone May 10, 2026

ehuss mentioned this pull request May 11, 2026

Update link_name for updated restrictions rust-lang/reference#2268

Merged

traviscross added needs-reference-pr This language change needs an approved Reference PR to proceed. missed-reference-pr This language change needed a Reference PR and was merged without it. labels May 26, 2026

pull Bot pushed a commit to Arstman/reference that referenced this pull request May 26, 2026

Update link_name for updated restrictions

7b88ecb

rust-lang/rust#155817 added some restrictions on the symbol name in the `link_name` attribute. The name cannot be empty or contain null bytes.

		#[link_name = "@GLIBC_2.2.5"]
		pub safe fn exit_1(status: i32) -> !; //~ ERROR link name must be well-formed if link kind is `raw-dylib`

Uh oh!

Conversation

folkertdev commented Apr 26, 2026

Uh oh!

rustbot commented Apr 26, 2026

Uh oh!

mejrs left a comment • edited by rustbot Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Uh oh!

This comment has been minimized.

folkertdev Apr 26, 2026 • edited by rustbot Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

This comment has been minimized.

This comment has been minimized.

traviscross commented Apr 29, 2026

Uh oh!

rust-rfcbot commented Apr 29, 2026 • edited by joshtriplett Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

rust-rfcbot commented Apr 29, 2026

Uh oh!

rust-rfcbot commented May 9, 2026

Uh oh!

folkertdev commented May 9, 2026

Uh oh!

rust-bors Bot commented May 9, 2026

Uh oh!

folkertdev commented May 9, 2026

Uh oh!

rust-bors Bot commented May 9, 2026

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

8 participants

mejrs left a comment •

edited by rustbot

Loading

folkertdev Apr 26, 2026 •

edited by rustbot

Loading

rust-rfcbot commented Apr 29, 2026 •

edited by joshtriplett

Loading