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suggest removing return type on use of void - #156381

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suggest removing return type on use of void#156381
euclio wants to merge 1 commit into
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euclio:void-suggest

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@euclio

@euclio euclio commented May 10, 2026

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Fixes #100972 (comment).

This PR suggests removing the return type entirely if the user writes -> void, expecting it to work like C or TypeScript.

@rustbot rustbot added 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 May 10, 2026
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rustbot commented May 10, 2026

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r? @ShoyuVanilla

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@Kivooeo

Kivooeo commented May 10, 2026

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just wondering how often is possible to see this?

tbh i think is hard to know what user is meant by -> void, maybe user wanted to return c_void raw pointer, or they do have or had a void variable somewhere

&& expected.starts_with("struct")
{
("`async` blocks are only allowed in Rust 2018 or later".to_string(), suggestion)
} else if item_str.as_str() == "void"

@Enselic Enselic Jul 13, 2026

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Wouldn't it be nicer to add the new logic to compiler/rustc_lint/src/c_void_returns.rs that https://github.com/rust-lang/rust/pull/156379/changes added?

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@rustbot rustbot 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 Jul 13, 2026
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Reminder, once the PR becomes ready for a review, use @rustbot ready.

@Enselic Enselic left a comment

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(re-adding comment that I accidentally deleted)

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Can you add a test when there is a valid type called void please, so we can see how rustc behaves in that case? Probably best to have the void type privatley scoped inside a mod { } so we don't need another file for the test.

Also consider unifying this test with the existing core::ffi::c_void test somehow.

@rust-bors

rust-bors Bot commented Jul 29, 2026

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☔ The latest upstream changes (presumably #160112) made this pull request unmergeable. Please resolve the merge conflicts by rebasing.

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Trying to return c_void should suggest to return () instead

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