--- title: Rust team warns of WebAssembly change | daily.dev description: The Rust team has announced a breaking change for WebAssembly targets: the --allow-undefined flag passed to wasm-ld will be removed, landing in nightly builds... canonical: https://daily.dev/posts/rust-team-warns-of-webassembly-change-b9vvopmgq twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Rust team warns of WebAssembly change | daily.dev og:description: The Rust team has announced a breaking change for WebAssembly targets: the --allow-undefined flag passed to wasm-ld will be removed, landing in nightly builds... og:url: https://daily.dev/posts/rust-team-warns-of-webassembly-change-b9vvopmgq og:image: https://api.daily.dev/og/posts/B9VvopMGq.png og:image:alt: Rust team warns of WebAssembly change 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. # Rust team warns of WebAssembly change **[InfoWorld](https://daily.dev/sources/infoworld)** · 3 min read · 34 upvotes · 0 comments ## Summary The Rust team has announced a breaking change for WebAssembly targets: the --allow-undefined flag passed to wasm-ld will be removed, landing in nightly builds soon and shipping with Rust 1.96 on 2026-05-28. This flag has historically allowed undefined symbols to silently become imports rather than linker errors, causing subtle bugs like typos in symbol names producing broken binaries instead of compile-time errors. The change aligns WebAssembly behavior with native platforms, where undefined symbols are errors by default. In practice, most projects are not expected to break, and the change should improve diagnostics for misconfigured builds. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Similar posts on daily.dev - [Announcing Rust 1.97.0](https://daily.dev/posts/announcing-rust-1-97-0-fqxhq3pfj) · Rust · 22 upvotes · 0 comments --- Tags: [#rust](https://daily.dev/tags/rust), [#webassembly](https://daily.dev/tags/webassembly) [View this post on daily.dev](https://daily.dev/posts/rust-team-warns-of-webassembly-change-b9vvopmgq) ```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":"Rust team warns of WebAssembly change","url":"https://daily.dev/posts/rust-team-warns-of-webassembly-change-b9vvopmgq","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/rust-team-warns-of-webassembly-change-b9vvopmgq"},"datePublished":"2026-04-07T04:53:52.647Z","dateModified":"2026-04-07T04:54:29.413Z","description":"The Rust team has announced a breaking change for WebAssembly targets: the --allow-undefined flag passed to wasm-ld will be removed, landing in nightly builds...","image":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/d4396e8a4f4fc34bd6efea14e2445479?_a=AQAEuop","thumbnailUrl":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/d4396e8a4f4fc34bd6efea14e2445479?_a=AQAEuop","isAccessibleForFree":true,"articleSection":"InfoWorld","inLanguage":"en","publisher":{"@type":"Organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180}},"author":{"@type":"Organization","name":"InfoWorld","logo":"https://media.daily.dev/image/upload/t_logo,f_auto/v1/logos/bf6d68a999064029b0bb09aa6268f1f3","url":"https://daily.dev/sources/infoworld"},"commentCount":0,"discussionUrl":"https://daily.dev/posts/rust-team-warns-of-webassembly-change-b9vvopmgq","interactionStatistic":[{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":34},{"@type":"InteractionCounter","interactionType":{"@type":"CommentAction"},"userInteractionCount":0}],"keywords":"rust,webassembly","timeRequired":"PT3M"} {"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://daily.dev"},{"@type":"ListItem","position":2,"name":"InfoWorld","item":"https://daily.dev/sources/infoworld"},{"@type":"ListItem","position":3,"name":"Rust team warns of WebAssembly change"}]} ```