The culprit of CDRIVER-2759 was passing a function with the wrong type to a variadic list. Reading variadic arguments in C is not type safe, so there was no compiler warning/error.

We could do type checking when TestSuite_AddFull is called by wrapping the variadic arguments with no-op function calls using preprocessor defines. E.g. something along the lines of this:

#define TestSuite_AddFull(_suite, _name, _func, _dtor, _ctx, ...) \
 _TestSuite_AddFull (_suite, _name, _func, _dtor, _ctx, FOREACH(TypeCheck, __VA_ARGS__) NULL)
 

Where this would expand to:

_TestSuite_AddFull (_suite, _name, _func, _dtor, _ctx, TypeCheck(chk1), TypeCheck(chk2), TypeCheck(chk3), null)

Therefore, the caller does the type check. We don't have any mechanism for doing a foreach with the preprocessor. See this example and P99_FOR.