In safety-critical software development, trust is earned, not assumed, and must be built on evidence. Open-source compilers such as GCC and Clang are widely used: they are powerful, mature and continuously evolving. Ultimately, what matters is not where the compiler comes from, but how confidently we can demonstrate that the compiler does what it is supposed to do.
Functional safety standards such as ISO 26262 or IEC 61508 make this distinction very clear. They don’t ask whether your compiler is proprietary or open source; they require it to be properly qualified. Qualification means showing, through objective evidence, that the compiler reliably translates source code into executable code without introducing defects. In our experience, the most practical route to qualification is through validation: demonstrating, with an independent test suite, that the compiler behaves according to the language standard.
This “black box” approach to qualification works well for open-source compilers. It allows developers to use them without needing to inspect or control the tools’ internal development processes. While open-source projects often have good governance, they are usually not designed with functional safety in mind. Using a test suite that is grounded in the ISO language definition, one can systematically verify the compiler’s output, document known issues and workarounds, and build the evidence needed for certification.
Once a compiler is qualified for a specific use case with a well-established test framework, the benefits extend far beyond that single project. The framework can be reused across future projects, compilers or versions. It removes the need for repeated verification at the object-code level, while maintaining compliance and transparency. Risks and costs are reduced for teams working on long-lifecycle products.
At Solid Sands, we know from experience that there are no intrinsic barriers to using open-source compilers in safety-critical domains. Functional safety standards are about demonstrating confidence through evidence, not reputation. With the right process, any high-quality compiler can become a trusted part of a certified toolchain.
Marcel Beemster, CTO