If you store a boolean value as an Objective-C object NSNumber *X, and want to see if it's true or false, than it's not a good idea to write this check as 'X == YES'. Because X is a pointer, and it is unlikely that it's equal to 1. You perhaps wanted to say [X boolValue] instead. Similarly, instead of X == 3, you'd certainly want to write something like [X intValue] == 3.
Similarly, in XNU/driver code, if you have a C++ object OSBoolean *X, which points to one of the two immutable objects - kOSBooleanTrue or kOSBooleanFalse , it's not a good idea to convert X to a C++ bool directly (eg. bool B = X). You want to compare it to kOSBooleanTrue or call the ->isTrue() method instead.
Bugs of both kinds have been noticed in real-world code, so i'm attempting to make a simple checker for that. It is purely AST-based and moreover uses only ASTMatchers for everything (which makes it the first analyzer checker to use AST matchers). In fact i'm not sure if this checker should be in the analyzer or in clang-tidy; there should be no problem to move it around.
I'm still going to tweak these matchers a bit, as i'm in the middle of gathering statistics.
"number pointers" -> "objects representing numbers"