GoKawiilLWN discusses efforts to curb undefined behavior in C standard
An LWN.net article recounts a talk explaining why undefined behavior exists in C and how the language's standard, dating back to C89, was built around an abstract machine model to accommodate diverse historical hardware. The speaker outlined C's enduring strengths—portability, fast compilation, predictable binaries—while detailing how the standard only guarantees 'observable' behavior, leaving much else open to compiler implementers.
GoKawiil's interpretation of the reporting above, not reported fact.
Undefined and implementation-defined behavior in C has long been a source of bugs and security vulnerabilities, so efforts to document or reduce it could make the language safer without sacrificing performance. This matters because C remains foundational to operating systems, embedded devices, and infrastructure software, and any shift in how its standard treats ambiguous behavior could influence compiler design and developer practices industry-wide.
- C's semantics are defined via an abstract machine model dating to the C89 standard.
- Only 'observable' behavior, like volatile variable access, must match the abstract machine exactly.
- Much of C's undefined/implementation-defined behavior exists due to historical hardware diversity, giving compilers flexibility.
The C Programming Language (Kernighan & Ritchie) — If you're digging into the nuances of undefined behavior in C, there's no better companion than the classic K&R text that explains the language's core philosophy and quirks. It's a timeless reference that helps you understand why C behaves the way it does at the hardware level.
See The C Programming Language (Kernighan & Ritchie) on Amazon → Affiliate link — we may earn a commission on purchases, at no extra cost to you. Product picked by AI based on this article; it is not a tested recommendation.Source: lwn.net, 2026-10-09
Published there as: “Reducing undefined behavior in the C language”
Read the original report → The summary and analysis above are GoKawiil's own, written from reporting by the source above. Facts and quotes belong to the original publisher.