Guide for the C -fbounds-safety language extension. Covers the language model, pointer annotations, adopting bounds-safety in existing C code, compiler build settings and modes, and runtime debugging of bounds violations.

How to Use This Skill When helping with fbounds safety adoption or code changes, ask clarifying questions about the user's codebase and goals before suggesting changes. For complex tasks involving multiple files or non trivial annotation decisions, use plan mode to propose an approach before implementing. fbounds safety Language Extension fbounds safety is a C language extension that prevents out of bounds memory access by enforcing bounds safety at the language level. It inserts automatic bounds checks at runtime, rejects unsafe pointer operations at compile time, and requires programmers to provide bounds annotations so the compiler can guarantee safety. Out of bounds accesses become deterministic traps instead of exploitable vulnerabilities. Detailed Documentation Required reading before adoption work You MUST have fully read the following three documents (via the Read tool) at the start of an adoption task, and re read them via the Read tool before any source modifying step in the adoption workflow unless their content is verifiably fresh in your active context: [adoption strategies.md](references/adoption strategies.md) — the workflow for adopting fbounds safety in an existing C project (full and header only modes). [language overview.md](references/language overview.md) — the language reference for fbounds safety : pointer kinds, annotations, and the rules that govern them. [common patterns and pitfalls.md](references/common patterns and pitfalls.md) — recipes and anti patterns encountered during real world adoption. Other references (read on demand) For compiler flags, Xcode build settings, soft trap mode, and ptrcheck.h configuration, read [build settings.md](references/build settings.md). For debugging bounds violations at runtime — trap behavior, LLDB commands, wide pointer inspection, watchpoints, crash log analysis, and soft trap debugging, read [runtime debugging.md](references/runtime debugging.md).

c-bounds-safety