Regarding Bug 46268 (Comparison against fixed-point type leads to crash).
I have analyzed the stack trace and reproduced the issue in my local build. I see the crash happens in the function getAsComplexIntegerType() (clang/lib/AST/type.cpp).
In this case, the const auto *Complex = getAs() is NULL, so the function returns NULL, it causes crash. I am not sure why auto *Complex = getAs() is NULL, If anyone knows about this function, please let me know.