Check mutation subject for header file clashes

[ambergorzynski]

Dredd includes several header files to support mutation. However, errors occur if the mutation subject contains different versions of these header files.

For example, Mesa includes c11/threads.h (e.g. here), while Dredd includes threads.h. This results in conflicting type errors and redeclaration errors.

I have resolved this issue within the Mesa mutation by modifying the mutated files to include c11/threads.h instead of threads.h. It would be good to consider a more general solution.

[afd]

Thanks - could you look at addressing this along the following lines:

• Add a string command line option, "--c-threads-header" (requires changing this file)
• Add a corresponding option here, defaulting to "threads.h" (or whatever the current default is)
• Adjust the code in this file that emits the C prelude so that it queries the option to determine what to emit

It's generally nice to have a unit test for these kinds of changes but in this case that might be tough, so perhaps instead we can add Mesa to the list of projects that are tested during CI - I'll open a separate issue for that.

[afd]

As discussed live, we may want to put this on hold as the use of c11/threads.h seems to be specific to Mesa.