Rust enums can surprisingly be smaller than expected. While naively, one might assume an enum's size is determined by the largest variant plus a discriminant to track which variant is active, the compiler optimizes this. If an enum's largest variant contains data with internal padding, the discriminant can sometimes be stored within that padding, avoiding an increase in the overall size. This optimization applies even when using #[repr(C)] or #[repr(u8)], so long as the layout allows it. Essentially, the compiler cleverly utilizes existing unused space within variants to store the variant tag, minimizing the enum's memory footprint.
C3 is a new programming language designed as a modern alternative to C. It aims to be safer and easier to use while maintaining C's performance and low-level control. Key features include optional memory safety through compile-time checks and garbage collection, improved syntax and error messages, and built-in modularity. The project is actively under development and includes a self-hosting compiler written in C3. The goal is to provide a practical language for systems programming and other performance-sensitive domains while mitigating common C pitfalls.
HN users discuss C3's goals and features, expressing both interest and skepticism. Several question the need for another C-like language, especially given the continued development of C and C++. Some appreciate the focus on safety and preventing common C errors, while others find the changes too drastic a departure from C's philosophy. There's debate about the practicality of automatic memory management in systems programming, and some concern over the runtime overhead it might introduce. The project's early stage is noted, and some express reservations about its long-term viability and community adoption. Others are more optimistic, praising the clear documentation and expressing interest in following its progress. The use of Python for the compiler is also a point of discussion.
This post details a method for using rr, a record and replay debugger, with Docker and Podman to debug applications in containerized environments, even on distros where rr isn't officially supported. The core of the approach involves creating a privileged debugging container with the necessary rr dependencies, mounting the target container's filesystem, and then using rr within the debugging container to record and replay the execution of the application inside the mounted container. This allows developers to leverage rr's powerful debugging capabilities, including reverse debugging, in a consistent and reproducible way regardless of the underlying container runtime or host distribution. The post provides detailed instructions and scripts to simplify the process, making it easier to adopt rr for containerized development workflows.
HN users generally praised the approach of using rr for debugging, highlighting its usefulness for complex, hard-to-reproduce bugs. Several commenters shared their positive experiences and successful debugging stories using rr. Some discussion revolved around the limitations of rr, specifically its performance overhead and compatibility issues with certain programs. The difficulty of debugging optimized code was mentioned, as was the need for improved tooling in general. A few users expressed interest in exploring similar tools and approaches for other operating systems besides Linux. One user suggested that the "replay everywhere" aspect is the most crucial part, emphasizing its importance for collaborative debugging and sharing reproducible bug reports.
Jakt is a statically-typed, compiled programming language designed for performance and ease of use, with a focus on systems programming, game development, and GUI applications. Inspired by C++, Rust, and other modern languages, it features manual memory management, optional garbage collection, compile-time evaluation, and a friendly syntax. Developed alongside the SerenityOS operating system, Jakt aims to offer a robust and modern alternative for building performant and maintainable software while prioritizing developer productivity.
Hacker News users discuss Jakt's resemblance to C++, Rust, and Swift, noting its potential appeal to those familiar with these languages. Several commenters express interest in its development, praising its apparent simplicity and clean design, particularly the ownership model and memory management. Some skepticism arises about the long-term viability of another niche language, and concerns are voiced about potential performance limitations due to garbage collection. The cross-compilation ability for WebAssembly also generated interest, with users envisioning potential applications. A few commenters mention the project's active and welcoming community as a positive aspect. Overall, the comments indicate a cautious optimism towards Jakt, with many intrigued by its features but also mindful of the challenges facing a new programming language.
The author recounts their teenage experience developing a rudimentary operating system for the Inmos Transputer. Fascinated by parallel processing, they created a system capable of multitasking and inter-process communication using the Transputer's unique link architecture. The OS, written in Occam, featured a kernel, device drivers, and a command-line interface, demonstrating a surprisingly sophisticated understanding of OS principles for a young programmer. Despite its limitations, like a lack of memory protection and a simple scheduler, the project provided valuable learning experiences in systems programming and showcased the potential of the Transputer's parallel processing capabilities.
Hacker News users discussed the blog post about a teen's experience developing a Transputer OS, largely focusing on the impressive nature of the project for someone so young. Several commenters reminisced about their own early programming experiences, often involving simpler systems like the Z80 or 6502. Some discussed the specific challenges of the Transputer architecture, like the difficulty of debugging and the limitations of the Occam language. A few users questioned the true complexity of the OS, suggesting it might be more accurately described as a kernel. Others shared links to resources for learning more about Transputers and Occam. The overall sentiment was one of admiration for the author's initiative and technical skills at a young age.
"The Night Watch" argues that modern operating systems are overly complex and difficult to secure due to the accretion of features and legacy code. It proposes a "clean-slate" approach, advocating for simpler, more formally verifiable microkernels. This would entail moving much of the OS functionality into user space, enabling better isolation and fault containment. While acknowledging the challenges of such a radical shift, including performance concerns and the enormous effort required to rebuild the software ecosystem, the paper contends that the long-term benefits of improved security and reliability outweigh the costs. It emphasizes that the current trajectory of increasingly complex OSes is unsustainable and that a fundamental rethinking of system design is crucial to address the growing security threats facing modern computing.
HN users discuss James Mickens' humorous USENIX keynote, "The Night Watch," focusing on its entertaining delivery and insightful points about the complexities and frustrations of systems work. Several commenters praise Mickens' unique presentation style and the relatable nature of his anecdotes about debugging, legacy code, and the challenges of managing distributed systems. Some highlight specific memorable quotes and jokes, appreciating the blend of humor and technical depth. Others reflect on the timeless nature of the talk, noting how the issues discussed remain relevant years later. A few commenters express interest in seeing a video recording of the presentation.
Driven by a desire for simplicity and performance in a personal project involving embedded systems and game development, the author rediscovered their passion for C. After years of working with higher-level languages, they found the direct control and predictable behavior of C refreshing and efficient. This shift allowed them to focus on core programming principles and optimize their code for resource-constrained environments, ultimately leading to a more satisfying and performant outcome than they felt was achievable with more complex tools. They argue that while modern languages offer conveniences, C's close-to-the-metal nature provides a unique learning experience and performance advantage, particularly for certain applications.
HN commenters largely agree with the author's points about C's advantages, particularly its predictability and control over performance. Several praised the feeling of being "close to the metal" and the satisfaction of understanding exactly how the code interacts with the hardware. Some offered additional benefits of C, such as easier debugging due to its simpler execution model and its usefulness in constrained environments. A few commenters cautioned against romanticizing C, pointing out its drawbacks like manual memory management and the potential for security vulnerabilities. One commenter suggested Zig as a modern alternative that addresses some of C's shortcomings while maintaining its performance benefits. The discussion also touched on the enduring relevance of C, particularly in foundational systems and performance-critical applications.
The blog post "An epic treatise on error models for systems programming languages" explores the landscape of error handling strategies, arguing that current approaches in languages like C, C++, Go, and Rust are insufficient for robust systems programming. It criticizes unchecked exceptions for their potential to cause undefined behavior and resource leaks, while also finding fault with error codes and checked exceptions for their verbosity and tendency to hinder code flow. The author advocates for a more comprehensive error model based on "algebraic effects," which allows developers to precisely define and handle various error scenarios while maintaining control over resource management and program termination. This approach aims to combine the benefits of different error handling mechanisms while mitigating their respective drawbacks, ultimately promoting greater reliability and predictability in systems software.
HN commenters largely praised the article for its thoroughness and clarity in explaining error handling strategies. Several appreciated the author's balanced approach, presenting the tradeoffs of each model without overtly favoring one. Some highlighted the insightful discussion of checked exceptions and their limitations, particularly in relation to algebraic error types and error-returning functions. A few commenters offered additional perspectives, including the importance of distinguishing between recoverable and unrecoverable errors, and the potential benefits of static analysis tools in managing error handling. The overall sentiment was positive, with many thanking the author for providing a valuable resource for systems programmers.
The Hacker News post asks users about their experiences with lesser-known systems programming languages. The author is seeking alternatives to C/C++ and Rust, specifically languages offering good performance, memory management control, and a pleasant development experience. They express interest in exploring options like Zig, Odin, Jai, and Nim, and are curious about other languages the community might be using for low-level tasks, driver development, embedded systems, or performance-critical applications.
The Hacker News comments discuss various less-popular systems programming languages and their use cases. Several commenters advocate for Zig, praising its simplicity, control over memory management, and growing ecosystem. Others mention Nim, highlighting its metaprogramming capabilities and Python-like syntax. Rust also receives some attention, albeit with acknowledgements of its steeper learning curve. More niche languages like Odin, Jai, and Hare are brought up, often in the context of game development or performance-critical applications. Some commenters express skepticism about newer languages gaining widespread adoption due to the network effects of established options like C and C++. The discussion also touches on the importance of considering the specific project requirements and team expertise when choosing a language.
The YouTube video "Microsoft is Getting Rusty" argues that Microsoft is increasingly adopting the Rust programming language due to its memory safety and performance benefits, particularly in areas where C++ has historically been problematic. The video highlights Microsoft's growing use of Rust in various projects like Azure and Windows, citing examples like rewriting core Windows components. It emphasizes that while C++ remains important, Rust is seen as a crucial tool for improving the security and reliability of Microsoft's software, and suggests this trend will likely continue as Rust matures and gains wider adoption within the company.
Hacker News users discussed Microsoft's increasing use of Rust, generally expressing optimism about its memory safety benefits and suitability for performance-sensitive systems programming. Some commenters noted Rust's steep learning curve, but acknowledged its potential to mitigate vulnerabilities prevalent in C/C++ codebases. Several users shared personal experiences with Rust, highlighting its positive impact on their projects. The discussion also touched upon the challenges of integrating Rust into existing projects and the importance of tooling and community support. A few comments expressed skepticism, questioning the long-term viability of Rust and its ability to fully replace C/C++. Overall, the comments reflect a cautious but positive outlook on Microsoft's adoption of Rust.
Greg Kroah-Hartman's post argues that new drivers and kernel modules being written in Rust benefit the entire Linux kernel community. He emphasizes that Rust's memory safety features improve overall kernel stability and security, reducing potential bugs and vulnerabilities for everyone, even those not directly involved with Rust code. This advantage outweighs any perceived downsides like increased code complexity or a steeper learning curve for some developers. The improved safety and resulting stability ultimately reduces maintenance burden and allows developers to focus on new features instead of bug fixes, benefiting the entire ecosystem.
HN commenters largely agree with Greg KH's assessment of Rust's benefits for the kernel. Several highlight the improved memory safety and the potential for catching bugs early in the development process as significant advantages. Some express excitement about the prospect of new drivers and filesystems written in Rust, while others acknowledge the learning curve for kernel developers. A few commenters raise concerns, including the increased complexity of debugging Rust code in the kernel and the potential performance overhead. One commenter questions the long-term maintenance implications of introducing a new language, wondering if it might exacerbate the already challenging task of maintaining the kernel. Another suggests that the real win will be determined by whether Rust truly reduces the number of CVEs related to memory safety issues in the long run.
After a year of using the uv HTTP server for production, the author found it performant and easy to integrate with existing C code, praising its small binary size, minimal dependencies, and speed. However, the project is relatively immature, leading to occasional bugs and missing features compared to more established servers like Nginx or Caddy. While documentation has improved, it still lacks depth. The author concludes that uv is a solid choice for projects prioritizing performance and tight C integration, especially when resources are constrained. However, those needing a feature-rich and stable solution might be better served by a more mature alternative. Ultimately, the decision to migrate depends on individual project needs and risk tolerance.
Hacker News users generally reacted positively to the author's experience with the uv terminal multiplexer. Several commenters echoed the author's praise for uv's speed and responsiveness, particularly compared to alternatives like tmux. Some highlighted specific features they appreciated, such as the intuitive copy-paste functionality and the project's active development. A few users mentioned minor issues or missing features, like lack of support for nested sessions or certain keybindings, but these were generally framed as minor inconveniences rather than major drawbacks. Overall, the sentiment leaned towards recommending uv as a strong contender in the terminal multiplexer space, especially for those prioritizing performance.
RustOwl is a tool that visually represents Rust's ownership and borrowing system. It analyzes Rust code and generates diagrams illustrating the lifetimes of variables, how ownership is transferred, and where borrows occur. This allows developers to more easily understand complex ownership scenarios and debug potential issues like dangling pointers or data races, providing a clear, graphical representation of the code's memory management. The tool helps to demystify Rust's core concepts by visually mapping how values are owned and borrowed throughout their lifetime, clarifying the relationship between different parts of the code and enhancing overall code comprehension.
HN users generally expressed interest in RustOwl, particularly its potential as a learning tool for Rust's complex ownership and borrowing system. Some suggested improvements, like adding support for visualizing more advanced concepts like Rc/Arc, mutexes, and asynchronous code. Others discussed its potential use in debugging, especially for larger projects where ownership issues become harder to track mentally. A few users compared it to existing tools like Rustviz and pointed out potential limitations in fully representing all of Rust's nuances visually. The overall sentiment appears positive, with many seeing it as a valuable contribution to the Rust ecosystem.
This blog post details creating a basic Windows driver using Rust. It leverages the windows crate for Windows API bindings and the wdk-sys crate for lower-level WDK access. The driver implements a minimal "DispatchCreateClose" routine, handling device creation and closure. The post walks through setting up the Rust development environment, including Cargo configuration and build process adjustments for driver compilation. It highlights using the wdk-build crate for simplifying the build process and generating the necessary INF file for driver installation. Finally, it demonstrates loading and unloading the driver using the DevCon utility, providing a practical example of the entire workflow from development to deployment.
Hacker News users discussed the challenges and advantages of writing Windows drivers in Rust. Several commenters pointed out the difficulty of working with the Windows Driver Kit (WDK) and its C/C++ focus, contrasting it with Rust's memory safety and modern tooling. Some highlighted the potential for improved driver stability and security with Rust. The conversation also touched on existing Rust wrappers for the WDK, the maturity of Rust driver development, and the complexities of interrupt handling. One user questioned the overall benefit, arguing that the difficulty of writing drivers stems from inherent hardware complexities more than language choice. Another pointed out the limited use of high-level languages in kernel-mode drivers due to real-time constraints.
The blog post argues for a more holistic approach to debugging and performance analysis by combining various tools and data sources. It emphasizes the limitations of isolated tools like memory profilers, call graphs, exception reports, and telemetry, advocating instead for integrating them to provide "system-wide context." This richer context allows developers to understand not only what went wrong, but also why and how, enabling more effective and efficient troubleshooting. The post uses a fictional scenario involving a slow web service to illustrate how correlating data from different tools can pinpoint the root cause of a performance issue, which in their example turns out to be an unexpected interaction between a third-party library and the application's caching strategy.
Hacker News users discussed the blog post about system-wide context, focusing primarily on the practical challenges of implementing such a system. Several commenters pointed out the difficulty of handling circular dependencies and the potential performance overhead, particularly in garbage-collected languages. Some suggested alternative approaches like structured logging and distributed tracing, while others questioned the overall value proposition compared to existing debugging tools. The complexity of integrating with different programming languages and the potential for information overload were also raised as concerns. A few commenters expressed interest in the idea but acknowledged the significant engineering effort required to make it a reality. One compelling comment highlighted the potential benefits for debugging complex, distributed systems, where understanding the interplay of different components is crucial.
This blog post advocates for a "no-panic" approach to Rust systems programming, aiming to eliminate all panics in production code. The author argues that while panic! is useful during development, it's unsuitable for production systems where predictable failure handling is crucial. They propose using the ? operator extensively for error propagation and leveraging types like Result and Option to explicitly handle potential failures. This forces developers to consider and address all possible error scenarios, leading to more robust and reliable systems. The post also touches upon strategies for handling truly unrecoverable errors, suggesting techniques like logging the error and then halting the system gracefully, rather than relying on the unpredictable behavior of a panic.
HN commenters largely agree with the author's premise that the no_panic crate offers a useful approach for systems programming in Rust. Several highlight the benefit of forcing explicit error handling at compile time, preventing unexpected panics in production. Some discuss the trade-offs of increased verbosity and potential performance overhead compared to using Option or Result. One commenter points out a potential issue with using no_panic in interrupt handlers where unwinding is genuinely unsafe, suggesting careful consideration is needed when applying this technique. Another appreciates the blog post's clarity and the practical example provided. There's also a brief discussion on how the underlying mechanisms of no_panic work, including its use of static mutable variables and compiler intrinsics.
The author details their process of creating a WebAssembly (Wasm) virtual machine (VM) written entirely in C. Driven by a desire for a lightweight, embeddable Wasm runtime for resource-constrained environments, they built the VM from scratch, implementing core features like the stack-based execution model, linear memory, and basic WebAssembly System Interface (WASI) support. The project focused on simplicity and understandability over performance, serving primarily as a learning exercise and a platform for experimentation with Wasm. The post walks through key aspects of the VM's design and implementation, including parsing the Wasm binary format, handling function calls, and managing memory. It also highlights the challenges faced and lessons learned during the development process.
Hacker News users generally praised the author's clear writing style and the educational value of the post. Several commenters discussed the project's performance, noting that it's not optimized for speed and suggesting potential improvements like just-in-time compilation. Some shared their own experiences with WASM interpreters and related projects, including comparisons to other implementations and alternative approaches like using a stack machine. Others appreciated the detailed explanation of the parsing and execution process, finding it helpful for understanding WASM internals. A few users pointed out minor corrections or areas for potential enhancement in the code, demonstrating active engagement with the technical details.
Uscope is a new, from-scratch debugger for Linux written in C and Python. It aims to be a modern, user-friendly alternative to GDB, boasting a simpler, more intuitive command language and interface. Key features include reverse debugging capabilities, a TUI interface with mouse support, and integration with Python scripting for extended functionality. The project is currently under active development and welcomes contributions.
Hacker News users generally expressed interest in Uscope, praising its clean UI and the ambition of building a debugger from scratch. Several commenters questioned the practical need for a new debugger given existing robust options like GDB, LLDB, and Delve, wondering about Uscope's potential advantages. Some discussed the challenges of debugger development, highlighting the complexities of DWARF parsing and platform compatibility. A few users suggested integrations with other tools, like REPLs, and requested features like remote debugging. The novelty of a fresh approach to debugging generated curiosity, but skepticism regarding long-term viability and differentiation also emerged. Some expressed concerns about feature parity with existing debuggers and the sustainability of the project.
In Zig, a Writer is essentially a way to abstract writing data to various destinations. It's not a specific type, but rather an interface defined by a set of functions (like writeAll, writeByte, etc.) that any type can implement. This allows for flexible output handling, as code can be written to work with any Writer regardless of whether it targets a file, standard output, network socket, or an in-memory buffer. By passing a Writer instance to a function, you decouple data production from the specific output destination, promoting reusability and testability. This approach simplifies code by unifying the way data is written across different contexts.
Hacker News users discuss the benefits and drawbacks of Zig's Writer abstraction. Several commenters appreciate the explicit error handling and composability it offers, contrasting it favorably to C's FILE pointer and noting the difficulties of properly handling errors with the latter. Some questioned the ergonomics and verbosity, suggesting that try might be preferable to explicit if checks for every write operation. Others highlight the power of Writer for building complex, layered I/O operations and appreciate its generality, enabling writing to diverse destinations like files, network sockets, and in-memory buffers. The lack of implicit flushing is mentioned, with commenters acknowledging the tradeoffs between explicit control and potential performance impacts. Overall, the discussion revolves around the balance between explicitness, control, and ease of use provided by Zig's Writer.
Wild is a new, fast linker for Linux designed for significantly faster linking than traditional linkers like ld. It leverages parallelization and a novel approach to symbol resolution, claiming to be up to 4x faster for large projects like Firefox and Chromium. Wild aims to be drop-in compatible with existing workflows, requiring no changes to source code or build systems. It also offers advanced features like incremental linking and link-time optimization, further enhancing development speed. While still under development, Wild shows promise as a powerful tool to accelerate the build process for complex C++ projects.
HN commenters generally praised Wild's speed and innovative approach to linking. Several expressed excitement about its potential to significantly improve build times, particularly for large C++ projects. Some questioned its compatibility and maturity, noting it's still early in development. A few users shared their experiences testing Wild, reporting positive results but also mentioning some limitations and areas for improvement, like debugging support and handling of complex linking scenarios. There was also discussion about the technical details behind Wild's performance gains, including its use of parallelization and caching. A few commenters drew comparisons to other linkers like mold and lld, discussing their relative strengths and weaknesses.
Dan Luu's "Working with Files Is Hard" explores the surprising complexity of file I/O. While seemingly simple, file operations are fraught with subtle difficulties stemming from the interplay of operating systems, filesystems, programming languages, and hardware. The post dissects various common pitfalls, including partial writes, renaming and moving files across devices, unexpected caching behaviors, and the challenges of ensuring data integrity in the face of interruptions. Ultimately, the article highlights the importance of understanding these complexities and employing robust strategies, such as atomic operations and careful error handling, to build reliable file-handling code.
HN commenters largely agree with the premise that file handling is surprisingly complex. Many shared anecdotes reinforcing the difficulties encountered with different file systems, character encodings, and path manipulation. Some highlighted the problems of hidden characters causing issues, the challenges of cross-platform compatibility (especially Windows vs. *nix), and the subtle bugs that can arise from incorrect assumptions about file sizes or atomicity. A few pointed out the relative simplicity of dealing with files in Plan 9, and others mentioned more modern approaches like using memory-mapped files or higher-level libraries to abstract away some of the complexity. The lack of libraries to handle text files reliably across platforms was a recurring theme. A top comment emphasizes how corner cases, like filenames containing newlines or other special characters, are often overlooked until they cause real-world problems.
This guide provides a comprehensive introduction to BCPL programming on the Raspberry Pi. It covers setting up a BCPL environment, basic syntax and data types, control flow, procedures, and input/output operations. The guide also delves into more advanced topics like separate compilation, creating libraries, and interfacing with the operating system. It includes numerous examples and exercises, making it suitable for both beginners and those with prior programming experience looking to explore BCPL. The document emphasizes BCPL's simplicity and efficiency, particularly its suitability for low-level programming tasks on resource-constrained systems like the Raspberry Pi.
HN commenters expressed interest in BCPL due to its historical significance as a predecessor to C and its influence on Go. Some recalled using BCPL in the past, highlighting its simplicity and speed, and contrasting its design with C. A few users discussed specific aspects of the document, such as the choice of Raspberry Pi and the use of pre-built binaries, while others lamented the lack of easily accessible BCPL resources today. Several pointed out the educational value of the guide, particularly for understanding compiler construction and the evolution of programming languages. Overall, the comments reflected a mix of nostalgia, curiosity, and appreciation for BCPL's role in computing history.
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https://news.ycombinator.com/item?id=43616649
Hacker News users discussed the surprising optimization where Rust can reduce the size of an enum if its variants all have the same representation. Some commenters expressed admiration for this detail of the Rust compiler and its potential performance benefits. A few questioned the long-term stability of relying on this optimization, wondering if changes to the enum's variants could inadvertently increase its size in the future. Others delved into the specifics of how this optimization interacts with features like
repr(C)and niche filling optimizations. One user linked to a relevant section of the Rust Reference, further illuminating the compiler's behavior. The discussion also touched upon the potential downsides, such as making the generated assembly more complex, and how using#[repr(u8)]might offer a more predictable and explicit way to control enum size.The Hacker News post titled "A surprising enum size optimization in the Rust compiler," linking to an article about enum size optimization in Rust, has generated several comments discussing the nuances of this optimization and its implications.
Several commenters delve into the specifics of the niche-filling optimization discussed in the article. One commenter explains how this optimization interacts with the
reprattribute in Rust, clarifying that while#[repr(u8)]forces the enum to be represented as au8, the niche-filling optimization still applies when possible, even without explicitly setting a representation. They provide an example of how this works in practice, illustrating that even with#[repr(u8)], the enum can still be optimized to a smaller size if its variants allow.Another commenter discusses the trade-offs between size optimization and runtime performance, pointing out that while smaller sizes are generally desirable, they can sometimes lead to increased runtime costs due to extra operations needed for encoding and decoding the optimized representation. This commenter also explains how the Rust compiler's zero-cost abstraction principle influences these decisions.
The discussion also touches on the complexity of enum representations and the challenges in predicting the final size. One commenter mentions that the compiler's behavior can sometimes be counterintuitive, leading to unexpected sizes. They provide an example where adding a field to a struct within an enum variant can surprisingly decrease the overall size of the enum due to the way niche-filling interacts with alignment requirements.
Furthermore, a commenter contrasts Rust's approach with that of C/C++, highlighting the differences in enum representation and the potential for optimization in each language. They note that while C/C++ enums typically default to the size of an integer, Rust's approach allows for more compact representations, especially when niche-filling is possible.
Finally, the topic of
Option<NonZeroU8>is brought up, with commenters explaining how the compiler can optimize its size down to a single byte because theNonevariant can occupy the niche value of zero, while theSomevariant stores the non-zero value directly. This example illustrates a common and practical use case of niche-filling optimization in Rust.Overall, the comments section provides valuable insights into the intricacies of Rust's enum size optimization and its practical implications. They offer a deeper understanding of the trade-offs involved, the compiler's behavior, and how these optimizations can impact code size and performance.