Who contributed to Rust on June 27, 2026?

1 developer shipped this update, including workflows-miri[bot].

What were the notable Rust updates?

Limit splat AST and FnDecl to 255 args, Rollup merge of #158244 - kantnero:attribute-docs-deprecated-warn, r=GuillaumeGomez,traviscross, and Rollup merge of #158448 - GuillaumeGomez:cleanup-numbuffer, r=Amanieu.

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RUST COMPILER TIGHTENS FUNCTION ARGUMENT LIMITS, DOCS EXPAND

By RepoJournal · Filed 06:04 UTC on June 27, 2026 · About Rust

1 person shipped this

workflows-miri[bot] @workflows-miri[bot] 1 cited

The Rust compiler now caps function arguments at 255 to prevent AST bloat, while the standard library gets its first comprehensive attribute documentation.

The compiler shipped a hard limit on function arguments across both splat AST and FnDecl [1], closing a vector for pathological code that could balloon memory usage during compilation. This isn't a breaking change for real code - if you're hitting 255 arguments, you have bigger architectural problems - but it hardens the compiler against adversarial inputs. In parallel, Rust's attribute documentation reached a milestone [2]: built-in attributes like `deprecated`, `warn`, `allow`, `cfg`, `deny`, and `forbid` now have proper reference docs using the `#[doc(attribute)]` mechanism, part of a larger push to make the standard library self-documenting. The compiler team also cleaned up technical debt [3] by removing stale FIXME comments and replacing slower `ilog(10)` calls with the optimized `ilog10()` variant. Miri pulled the latest upstream changes [4] to stay synchronized with the nightly compiler. On crates.io, the openipc ecosystem expanded with four new hardware-focused crates [5] [6] [7] [8], targeting embedded platforms from web to RTL88xx drivers.

Action items

→ Review argument limits in any macro-heavy code or code generators that produce functions rust-lang/rust [plan]
→ Link to new attribute docs in your style guides and documentation rust-lang/rust [monitor]

References

[1] Limit splat AST and FnDecl to 255 args rust-lang/rust
[2] Rollup merge of #158244 - kantnero:attribute-docs-deprecated-warn, r=GuillaumeGomez,traviscross rust-lang/rust
[3] Rollup merge of #158448 - GuillaumeGomez:cleanup-numbuffer, r=Amanieu rust-lang/rust
[4] Automatic Rustup ↗ rust-lang/miri
[5] Create crate `openipc-web` rust-lang/crates.io-index
[6] Create crate `openipc-native` rust-lang/crates.io-index
[7] Create crate `openipc-rtl88xx` rust-lang/crates.io-index
[8] Create crate `openipc-core` rust-lang/crates.io-index

Quick answers

What shipped in Rust on June 27, 2026?: The Rust compiler now caps function arguments at 255 to prevent AST bloat, while the standard library gets its first comprehensive attribute documentation. In total, 89 commits and 17 pull requests landed.
Who contributed to Rust on June 27, 2026?: 1 developer shipped this update, including workflows-miri[bot].
What were the notable Rust updates?: Limit splat AST and FnDecl to 255 args, Rollup merge of #158244 - kantnero:attribute-docs-deprecated-warn, r=GuillaumeGomez,traviscross, and Rollup merge of #158448 - GuillaumeGomez:cleanup-numbuffer, r=Amanieu.

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