When matching C standard library functions in the checker, it's easy to forget that they are often implemented as macros that are expanded to compiler builtins. Such builtins would have a different name, so matching the callee identifier would fail, or may sometimes have more arguments than expected (so matching the exact number of arguments would fail, but this is fine as long as we have all the arguments that we need in their respective places.
This patch adds a set of flags to the CallDescription class so that to handle various special matching rules, and adds the first flag into this set, which enables a more fuzzy matching for functions that may be implemented as builtins.
I wonder if this is the right name. Do checker authors know the relationship between a standard library function and builtins? Maybe something like CDF_IsCStandardLibFunc would be more prescriptive when to set this? Or do we have non standard library builtins that we might want to match using this facility? The comment above is great, I just wonder if checker authors will read that. In case it does show up in the doxygen feel free to leave the name as is.