[LordHog]

In years past I worked for a couple different aerospace companies. Optimization for the tools had to be turned off, period! As sbradford26 mentioned, this was need for verification, especially for Software Verification Cases & Procedures document (SVCP). This is especially important for Level A. I worked on Level B LRUs.

The projects steered clear of C++ given there is a lot of code generated that is not easily trace to the written source if using C++ features (constructors and polymorphism as a couple examples). Yes, there are companies out there that do use C++ for aerospace, but I never worked at a company that did. The project also used in-house schedulers/executives. Boeing highly suggested to that company I was at, early 2000's, not to use a commercial RTOS (even a verified ones from companies like Green Hills or VxWorks). All companies developed a schedule/executive that suited the needs of the projects, but they were all very similar in the end.

I also worked at a company that developed solutions for industrial controls and they follow a similar path to DO-178B/C guidelines. The company followed IEC 61508 which had a very similar flow to DO-178B. All products, except one that was not safety critical, used C and used an in-house scheduler/executive also.

I took this from https://www.certon.com/do-178-development-certification/:

"Source to Object Code Trace Analysis (Level A Only) The compiler converts the Source Code into assembly object code before it is compatible with the target computer. For DAL A software, it is required to provide assurance that all assembly object code generated by the compiler is traceable to the source code. Any assembly object code that is not traceable directly to the source code requires additional verification to be performed in order to provide safety assurance and the absence of unintended behavior."

Certification Authorities Software Team (CAST) (a bit dated and I didn't try to find if a newer version exist) https://www.faa.gov/aircraft/air_cert/design_approvals/air_s...

Edit: For most projects, at least the ones I was on, 50% of the budget was allocated for validation/verification. Thus, reducing the additional work to verify code that was not directly related to source is always desired. One prime reason not to use C++.