--- title: Memory Safety’s Hardest Problem | daily.dev description: A brief but pointed analysis of memory safety's hardest unsolved problem: type confusion via tagged unions. When a union is initialized as one type, a pointer... canonical: https://daily.dev/posts/memory-safety-s-hardest-problem-ob8qh0lmc twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Memory Safety’s Hardest Problem | daily.dev og:description: A brief but pointed analysis of memory safety's hardest unsolved problem: type confusion via tagged unions. When a union is initialized as one type, a pointer... og:url: https://daily.dev/posts/memory-safety-s-hardest-problem-ob8qh0lmc og:image: https://api.daily.dev/og/posts/Ob8Qh0lMC.png og:image:alt: Memory Safety’s Hardest Problem og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Memory Safety’s Hardest Problem **[matklad](https://daily.dev/sources/matklad)** · 1 min read · 5 upvotes · 1 comments ## Summary A brief but pointed analysis of memory safety's hardest unsolved problem: type confusion via tagged unions. When a union is initialized as one type, a pointer taken to its internals, then overwritten with a different type, the pointer becomes dangerously mistyped. This issue breaks even Ada's safety guarantees. The post also argues that buffer overflows — the most exploitable memory error in practice — are trivially fixable with bounds checks, and laments that the industry missed Walter Bright's early insight about array syntax in C that could have prevented many vulnerabilities. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Community discussion Top comments from developers on daily.dev. **@khauma** · 3 upvotes > The example code is zig and they mention C but there is nothing here about rust (which is fine) but the tags should probably be updated so it gets in front of the correct audience. Fortunately, I follow both Rust and Zig but this should probably be rectified. ## Similar posts on daily.dev - [Memory safety is a matter of life and death](https://daily.dev/posts/memory-safety-is-a-matter-of-life-and-death-5zvkfxka2) · Lobsters · 11 upvotes · 1 comments - [Everything in C is undefined behavior](https://daily.dev/posts/everything-in-c-is-undefined-behavior-lf4o5xfht) · Hacker News · 21 upvotes · 1 comments - [Memory Safety Is …](https://daily.dev/posts/memory-safety-is--rqzrjfwnl) · matklad · 0 upvotes · 0 comments --- Tags: [#rust](https://daily.dev/tags/rust) [View this post on daily.dev](https://daily.dev/posts/memory-safety-s-hardest-problem-ob8qh0lmc) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"Memory Safety’s Hardest Problem","url":"https://daily.dev/posts/memory-safety-s-hardest-problem-ob8qh0lmc","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/memory-safety-s-hardest-problem-ob8qh0lmc"},"datePublished":"2026-07-20T13:21:06.128Z","dateModified":"2026-07-20T18:21:37.223Z","description":"A brief but pointed analysis of memory safety's hardest unsolved problem: type confusion via tagged unions. 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Fortunately, I follow both Rust and Zig but this should probably be rectified.","datePublished":"2026-07-20T17:34:30.723Z","url":"https://daily.dev/posts/Ob8Qh0lMC#c-Qta3Bwk3M","author":{"@type":"Person","name":"Kahlil Wallace","url":"https://daily.dev/khauma","image":"https://media.daily.dev/image/upload/s--QvppE9Ip--/f_auto/v1767378558/avatars/avatar_7eQFeSQRDx0muV3n92gxT?_a=BAMAK+ZW0"},"interactionStatistic":{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":3}}]} ```