[analyzer] Track whether an ObjC for-in loop had zero iterations.
An Objective-C for-in loop will have zero iterations if the collection is
empty. Previously, we could only detect this case if the program asked for
the collection's -count /before/ the for-in loop. Now, the analyzer
distinguishes for-in loops that had zero iterations from those with at
least one, and can use this information to constrain the result of calling
-count after the loop.
In order to make this actually useful, teach the checker that methods on
NSArray, NSDictionary, and the other immutable collection classes don't
change the count.
<rdar://problem/14992886>
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@194235 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed