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New keywords

New keywords Minimum Rust version: 1.27 Summary • dyn is a strict keyword, in 2015 it is a weak keyword. • async and await are strict keywords. • try is a reserved keyword. Motivation dyn Trait for trait objects The dyn Trait feature is the...

doc.rust-lang.org The Rust Edition Guide Book 2024-01-01 ~1 min read

Method dispatch for raw pointers to inference variables

Method dispatch for raw pointers to inference variables Summary • The tyvar_behind_raw_pointer lint is now a hard error. Details See Rust issue #46906 for details.

doc.rust-lang.org The Rust Edition Guide Book 2024-01-01 ~1 min read

Cargo changes

Cargo changes Summary • If there is a target definition in a Cargo.toml manifest, it no longer automatically disables automatic discovery of other targets. • Target paths of the form src/{target_name}.rs are no longer inferred for targets w...

doc.rust-lang.org The Rust Edition Guide Book 2024-01-01 ~1 min read

Rust 2021

Rust 2021 | Info | | | --- | --- | | RFC | #3085 | | Release version | 1.56.0 | The Rust 2021 Edition contains several changes that bring new capabilities and more consistency to the language, and opens up room for expansion in the future....

doc.rust-lang.org The Rust Edition Guide Book 2024-01-01 ~1 min read

Additions to the prelude

Additions to the prelude Summary • The TryInto, TryFrom and FromIterator traits are now part of the prelude. • This might make calls to trait methods ambiguous which could make some code fail to compile. Details The prelude of the standard...

doc.rust-lang.org The Rust Edition Guide Book 2024-01-01 ~5 min read

Default Cargo feature resolver

Default Cargo feature resolver Summary • edition = "2021" implies resolver = "2" in Cargo.toml. Details Since Rust 1.51.0, Cargo has opt-in support for a new feature resolver which can be activated with resolver = "2" in Cargo.toml. Startin...

doc.rust-lang.org The Rust Edition Guide Book 2024-01-01 ~5 min read

IntoIterator for arrays

IntoIterator for arrays Summary • Arrays implement IntoIterator in all editions. • Calls to IntoIterator::into_iter are hidden in Rust 2015 and Rust 2018 when using method call syntax (i.e., array.into_iter()). So, array.into_iter() still r...

doc.rust-lang.org The Rust Edition Guide Book 2024-01-01 ~2 min read

Disjoint capture in closures

Disjoint capture in closures Summary • || a.x + 1 now captures only a.x instead of a. • This can cause things to be dropped at different times or affect whether closures implement traits like Send or Clone. • If possible changes are detecte...

doc.rust-lang.org The Rust Edition Guide Book 2024-01-01 ~5 min read

Panic macro consistency

Panic macro consistency Summary • panic!(..) now always uses format_args!(..), just like println!(). • panic!("{") is no longer accepted, without escaping the { as {{. • panic!(x) is no longer accepted if x is not a string literal. • Use st...

doc.rust-lang.org The Rust Edition Guide Book 2024-01-01 ~2 min read

Reserved syntax

Reserved syntax Summary • any_identifier#, any_identifier"...", any_identifier'...', and 'any_identifier# are now reserved syntax, and no longer tokenize. • This is mostly relevant to macros. E.g. quote!{ #a#b } is no longer accepted. • It...

doc.rust-lang.org The Rust Edition Guide Book 2024-01-01 ~2 min read

Raw lifetimes

Raw lifetimes Summary • 'r#ident_or_keyword is now allowed as a lifetime, which allows using keywords such as 'r#fn. Details Raw lifetimes are introduced in the 2021 edition to support the ability to migrate to newer editions that introduce...

doc.rust-lang.org The Rust Edition Guide Book 2024-01-01 ~1 min read

Warnings promoted to errors

Warnings promoted to errors Summary • Code that triggered the bare_trait_objects and ellipsis_inclusive_range_patterns lints will error in Rust 2021. Details Two existing lints are becoming hard errors in Rust 2021, but these lints will rem...

doc.rust-lang.org The Rust Edition Guide Book 2024-01-01 ~1 min read

Or patterns in macro-rules

Or patterns in macro-rules Summary • How patterns work in macro_rules macros changes slightly: • $_:pat in macro_rules now matches usage of | too: e.g. A | B. • The new $_:pat_param behaves like $_:pat did before; it does not match (top lev...

doc.rust-lang.org The Rust Edition Guide Book 2024-01-01 ~2 min read

C-string literals

C-string literals Summary • Literals of the form c"foo" or cr"foo" represent a string of type &core::ffi::CStr. Details Starting with Rust 1.77, C-strings can be written using C-string literal syntax with the c or cr prefix. Previously, it...

doc.rust-lang.org The Rust Edition Guide Book 2024-01-01 ~1 min read

Rust 2024

Rust 2024 | Info | | | --- | --- | | RFC | #3501 | | Release version | 1.85.0 |

doc.rust-lang.org The Rust Edition Guide Book 2024-01-01 ~1 min read

Language

Language The following chapters detail changes to the language in the 2024 Edition.

doc.rust-lang.org The Rust Edition Guide Book 2024-01-01 ~1 min read

RPIT lifetime capture rules

RPIT lifetime capture rules This chapter describes changes related to the Lifetime Capture Rules 2024 introduced in RFC 3498, including how to use opaque type precise capturing (introduced in RFC 3617) to migrate your code. Summary • In Rus...

doc.rust-lang.org The Rust Edition Guide Book 2024-01-01 ~9 min read

if let temporary scope

if let temporary scope Summary • In an if let $pat = $expr { .. } else { .. } expression, the temporary values generated from evaluating $expr will be dropped before the program enters the else branch instead of after. Details The 2024 Edit...

doc.rust-lang.org The Rust Edition Guide Book 2024-01-01 ~3 min read

let chains in if and while

let chains in if and while Summary • Allow chaining of let expressions in the condition operand of if and while. Details Starting with the 2024 Edition, it is now allowed to have chaining of let expressions inside if and while condition ope...

doc.rust-lang.org The Rust Edition Guide Book 2024-01-01 ~1 min read

Tail expression temporary scope

Tail expression temporary scope Summary • Temporary values generated in evaluation of the tail expression of a function or closure body, or a block may now be dropped before local variables, and are sometimes not extended to the next larger...

doc.rust-lang.org The Rust Edition Guide Book 2024-01-01 ~3 min read