Discover the exciting new features introduced in Rust 1.79 and 1.80! The discussion highlights inline constant expressions and enhancements to global variables, boosting readability and resource management. Delve into frame pointers for improved debugging and the stabilization of unchecked arithmetic for optimized performance. Learn about advancements in string processing, including UTF-8 handling and new methods for slices. Don't miss the introduction of lazy initialization types and exclusive ranges in pattern matching, enhancing developer efficiency!
Rust 1.79 introduced inline const expressions, enhancing usability by allowing constants in various contexts, streamlining generics handling.
The new bounds in associated type positions in Rust 1.79 simplify trait implementations, improving code clarity and reducing verbosity.
Rust 1.80 added stringent safety measures by marking certain standard library functions as unsafe, reinforcing the language's commitment to code integrity.
Deep dives
Introduction of Inline Const Expressions
Inline const expressions allow for named constants to be declared within arbitrary contexts, enhancing flexibility compared to prior implementations. This means that you can create constants not just at the item level, but also in function parameters, scopes, and other expressions. This change improves usability when working with generics because constants within inline expressions can now reference generic parameters directly. Consequently, the compiler manages multiple const instantiations for different types, enhancing performance and code readability.
Streamlined Associated Type Bounds
In the Rust 179 release, bounds in associated type positions have been simplified, allowing developers to declare the bounds of associated types inline with the type parameters they relate to. This update alleviates verbosity in trait implementations, enabling a more compact syntax. For instance, developers can now specify bounds such as `T: Iterator` in a single line, reducing the cognitive load and improving code clarity. This functionality particularly benefits code with complex traits, enhancing ergonomics without compromising functionality.
Automatic Temporary Lifetime Extensions
Rust 179 introduced improved lifetime extensions for temporaries during conditional branches, allowing for reference storage beyond scope. This modification permits immediate temporaries within branches of if-else statements to have extended lifetimes based on returned references. For example, if references are generated from temporaries, those references remain valid for the duration needed, resolving issues like dangling references. This change helps developers write safer code by eliminating common pitfalls associated with lifetimes and temporaries.
Frame Pointers for Improved Debugging
The Rust standard library now includes frame pointers in its builds, enhancing debugging capabilities for developers. By retaining function frame pointers, the debugging process becomes significantly simpler by allowing easier stack trace analysis. Although frame pointers are not strictly necessary for execution, their inclusion is advantageous for providing more insightful debugging information when troubleshooting complex code. This feature reflects Rust's ongoing commitment to making development smoother and more efficient.
New Lints and Decreased Clippy Noise
New lints have been introduced, including one that discourages the use of manual clamp implementations to encourage standardized approaches. This lint has been moved to the pedantic group, meaning it will not be on by default, minimizing unnecessary noise in the codebase. This decision aims to prioritize impactful lints while reducing the workload on developers who encounter less critical suggestions. In addition, the Rust team remains attentive to balancing quality suggestions with the overall user experience.
Changes to Unsafe and the Standard Library
The standard library underwent notable changes, including making certain functions unsafe, reflecting best practices in error handling. For instance, functions concerning environment variables such as `set_var` became unsafe as their improper use could lead to riskier runtime behavior. This reinforces the philosophy that Rust prioritizes safety and soundness, rejecting previously acceptable patterns that could compromise code integrity. These adjustments illustrate a forward-looking mindset in Rust's development, continually evolving to enhance safety standards.
Jon and Ben discuss the highlights of the 1.79 and 1.80 releases of Rust.
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