Commit Graph

2 Commits

Author SHA1 Message Date
Nathan James e40a742a50 [clang-tidy] Change checks to use new isLanguageVersionSupported restriction
Summary: Modifies all checks that are language version dependent to use `isLanguageVersionSupported`

Reviewers: jdoerfert, lebedev.ri, aaron.ballman, gribozavr2, Eugene.Zelenko

Reviewed By: gribozavr2

Subscribers: wuzish, nemanjai, xazax.hun, hiraditya, kbarton, steven_wu, dexonsmith, arphaman, lebedev.ri, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D75340
2020-03-03 16:43:45 +00:00
Stephane Moore 2f6a52816f [clang-tidy] Add check for classes missing -hash ⚠️
Summary:
Apple documentation states that:
"If two objects are equal, they must have the same hash value. This last
point is particularly important if you define isEqual: in a subclass and
intend to put instances of that subclass into a collection. Make sure
you also define hash in your subclass."
https://developer.apple.com/documentation/objectivec/1418956-nsobject/1418795-isequal?language=objc

In many or all versions of libobjc, -[NSObject isEqual:] is a pointer
equality check and -[NSObject hash] returns the messaged object's
pointer. A relatively common form of developer error is for a developer to
override -isEqual: in a subclass without overriding -hash to ensure that
hashes are equal for objects that are equal.

It is assumed that an override of -isEqual: is a strong signal for
changing the object's equality operator to something other than pointer
equality which implies that a missing override of -hash could result in
distinct objects being equal but having distinct hashes because they are
independent instances. This added check flags classes that override
-isEqual: but inherit NSObject's implementation of -hash to warn of the
potential for unexpected behavior.

The proper implementation of -hash is the responsibility of the
developer and the check will only verify that the developer made an
effort to properly implement -hash. Developers can set up unit tests
to verify that their implementation of -hash is appropriate.

Test Notes:
Ran check-clang-tools.

Reviewers: aaron.ballman, benhamilton

Reviewed By: aaron.ballman

Subscribers: Eugene.Zelenko, mgorny, xazax.hun, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D67737

llvm-svn: 372445
2019-09-21 01:22:22 +00:00