{"id":43,"date":"2024-12-16T21:35:00","date_gmt":"2024-12-16T21:35:00","guid":{"rendered":"https:\/\/codegenblog.kinsta.cloud\/?p=43"},"modified":"2025-08-27T12:10:56","modified_gmt":"2025-08-27T12:10:56","slug":"automating-dead-code-removal-with-ai-and-static-analysis","status":"publish","type":"post","link":"https:\/\/codegen.com\/blog\/automating-dead-code-removal-with-ai-and-static-analysis\/","title":{"rendered":"Automating Dead Code Removal with AI and Static Analysis"},"content":{"rendered":"\n

Dead Code Removal Sucks \u2620\ufe0f<\/h3>\n\n\n\n

Dead code is a perennial source of tech debt in large codebases. As unused code and outdated feature flags accumulate, the codebase gets weighed down with countless intricate sets of if-else statements and functions. Engineers tiptoe around them, scared to delete them in case of breaking something else, so the dead code paths just lurk around indefinitely.<\/p>\n\n\n\n

Automated Solutions<\/h3>\n\n\n\n

Meta even wrote a whole internal tool, SCARF<\/a>, that uses advanced code analysis to safely delete unused code. SCARF creates and traverses code dependency graphs across multiple languages, and across API calls, in order to determine whether a piece of code is truly safe to remove\u2014and what else needs to be removed in conjunction with it. In five years, SCARF auto-deleted over 100M lines of code at Meta.<\/p>\n\n\n\n

Unfortunately, SCARF is not open source. But you might be wondering: in the age of AI tools, is SCARF still necessary? Can we just make AI remove dead code for us?<\/strong><\/p>\n\n\n\n

In a smaller codebase, sure. But, in a large codebase with complex cross-functional dependencies, it\u2019s hard to pass in enough context to an AI agent\u2014or to make it conduct a thorough enough code analysis\u2014to trust it to come up with consistently safe deletions.<\/p>\n\n\n\n

That\u2019s where a combined static analysis + AI tool can come in. Codegen combines code analysis with AI tools to auto-generate dead code deletion PRs<\/strong> that you can trust.<\/p>\n\n\n\n

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A small snippet of a dead code analysis that we ran on the Codegen internal codebase. Codegen’s static analysis tool mapped out all function dependencies and marked unused functions in red in this graph.<\/figcaption><\/figure>\n\n\n\n

Let\u2019s look at one very practical example of automated dead code deletion\u2014feature flag deletion<\/strong>.<\/p>\n\n\n\n

Feature Flag Deletion<\/h3>\n\n\n\n

Feature flags are a particularly pernicious form of dead code buildup. As Anton Zaides writes<\/a>:<\/p>\n\n\n\n