On a method call, the ObjCGenerics checker uses the type tracked by
DynamicTypePropagation for the receiver to to infer substituted parmeter types
for the called methods and warns when the argument type does not match the
parameter.
Unfortunately, using the tracked type can result in false positives when the
receiver has a non-invariant type parameter and has been intentionally upcast.
For example, becaue NSArray's type parameter is covaraint, the following code
is perfectly safe:
NSArray<NSString *> *allStrings = ...
NSDate *date = ...;
NSArray<NSObject *> *allObjects = allStrings;
NSArray<NSObject *> *moreObjects = [allObjects arrayByAddingObject:date];
but the checker currently warns that the date parameter is not an NSString *.
To avoid this kind of false positive, the checker will now only warn when
the class defining the called method has only invariant type parameters.
rdar://problem/28803951
llvm-svn: 288677
In the analyzer's path-sensitive reports, when a report goes through a branch
and the branch condition cannot be decided to be definitely true or false
(based on the previous execution path), an event piece is added that tells the
user that a new assumption is added upon the symbolic value of the branch
condition. For example, "Assuming 'a' is equal to 3".
The text of the assumption is hand-crafted in various manners depending on
the AST expression. If the AST expression is too complex and the text of
the assumption fails to be constructed, the event piece is omitted.
This causes loss of information and misunderstanding of the report.
Do not omit the event piece even if the expression is too complex;
add a piece with a generic text instead.
Differential Revision: https://reviews.llvm.org/D23300
llvm-svn: 283301
Fix a crash in the generics checker where DynamicTypePropagation tries
to get the superclass of a root class.
This is a spot-fix for a deeper issue where the checker makes assumptions
that may not hold about subtyping between the symbolically-tracked type of
a value and the compile-time types of a cast on that value.
I've added a TODO to address the underlying issue.
rdar://problem/26086914
llvm-svn: 269227
This patch adds hashes to the plist and html output to be able to identfy bugs
for suppressing false positives or diff results against a baseline. This hash
aims to be resilient for code evolution and is usable to identify bugs in two
different snapshots of the same software. One missing piece however is a
permanent unique identifier of the checker that produces the warning. Once that
issue is resolved, the hashes generated are going to change. Until that point
this feature is marked experimental, but it is suitable for early adoption.
Differential Revision: http://reviews.llvm.org/D10305
Original patch by: Bence Babati!
llvm-svn: 251011
Dominic Chen